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A  TEXT-BOOK 

OF 

MYCOLOGY  AND  PLANT 
PATHOLOGY 


HARSHBERGER 


A  TEXT-BOOK 

OF 

MYCOLOGY  AND  PLANT 
PATHOLOGY 


BY 

JOHN  W.  HARSHBERGER,  Ph.D. 

PROFESSOR    OF    BOTANY,    UNIVERSITY'  OF    PENNSYLVANIA;    MEMBER    OF 

THE  BOTANICAL  SOCIETY   OF  AMERICA;  VICE-PRESIDENT  OF  THE 

ECOLOGICAL  SOCIETY  OF  AMERICA,    ETC. 


WITH  271  ILLUSTRATIONS 


PHILADELPHIA 

P.  BLAKISTON'S  SON  &  CO. 

1012  WALNUT  STREET 


Copyright,  191 7,  by  P.  Blakiston's  Son  &  Co. 


THE  MAPLE  PRESS  YORK  PA 


PREFACE 

This  book  is  the  outcome  of  twenty-seven  years'  experience,  as  a 
teacher  of  botany,  during  which  fifteen  years  have  been  given  to  a 
graduate  course  on  the  morphology,  classification  and  physiology  of  the 
fungi,  and  five  years  to  a  course  which  combined  with  this  considera- 
tion a  parallel  study  of  the  most  important  cultural  and  inoculation 
methods  used  by  the  practical  bacteriologist  and  mycologist  at  the 
present  day.  The  English  and  Germans  have  led  in  the  production 
of  text-books  on  mycology  and  pathology;  Berkeley,  Smith,  Cooke 
and  Massee  in  England,  Frank,  Sorauer,  von  Tubeuf  and  Kiister  in 
Germany.  Americans  have  been  behind  in  this  important  field, 
notwithstanding,  that  American  plants  harbor  some  of  the  most 
destructive  fungi,  which,  through  our  careless  methods  of  agriculture 
and  horticulture  up  to  the  present,  are  annually  destructive  to  the 
extent  of  millions  of  dollars.  This  lack  is  being  rapidly  remedied  and 
the  appearance  of  text-books  by  Duggar,  Stevens,  Hall  and' Stevens, 
Mel  T.  Cook  and  general  monographs  by  Erwin  T.  Smith,  and  others, 
augurs  well  for  the  future  of  this  line  of  literary  and  scientific  labor. 
The  bacteriologists  have  led  and  mycologists  should  follow. 

The  following  pages  represent  in  a  much  extended  form  the  lectures 
and  laboratory  exercises  given  by  the  author  before  his  botanic  classes 
at  the  University  of  Pennsylvania,  and  before  public  audiences  else- 
where, especially,  Farmers'  Institutes  with  which  he  has  had  three 
years'  experience  as  a  lecturer  in  Pennsylvania.  The  arrangement  of 
the  text  has  been  suggested  by  the  needs  of  the  classroom  and  from  an 
acquaintance  with  similar  work  in  other  colleges  and  universities  in 
America.  It  is  hoped  that  the  book  and  the  suggestions,  as  to  teaching 
which  it  contains,  will  appeal  to  those  responsible  for  similar  courses. 
The  keys  are  given  with  the  anticipation  that  they  will  prove  useful 
to  the  student  and  teacher  who  desire  exercises  in  the  classification  of 
the  fungi:  The  illustrations  have  been  chosen  with  care,  and  credit  is 
given  in  all  cases  for  those  borrowed  from  other  books  and  monographs. 
The  author  hopes  that  the  book  is  reasonably  free  from  misleading 


<^ 


A(ii^  US'?  00 


statements,  and  that  it  will  prove  useful  to  the  teaching  and  student 
body.  The  exercises,  which  are  given  in  detailed  form  are  designed  to 
acquaint  the  student  with  the  methods  that  are  used  in  the  cultural 
investigation  of  the  bacteria  and  fungi.  It  is  also  designed  to  introduce 
the  student  to  the  highly  important  subject  of  Technical  Mycology. 

The  modern  demands  for  investigators  trained  in  technical  my- 
cology are  many.  The  health  bureaus  of  our  large  cities  need  men  and 
women,  who  can  make  a  study  of  the  milk,  water  and  food  supplies. 
The  men,  who  are  engaged  in  the  fermentation  industries,  frequently 
demand  expert  information  on  the  bacterial  and  fungal  organisms,  that 
are  either  useful,  or  harmful,  in  the  fermentation  process.  The  bread 
baker  should  have  someone  to  whom  questions  relative  to  his,  one  of  the 
oldest,  arts  could  be  referred.  The  canner  also  needs  such  expert 
advice.  The  farmer  depends  upon  the  fertility  of  his  soil  for  the  growth 
of  crops,  and  the  character  of  that  fertility  determines  whether  his 
crop  shall  be  a  large  or  a  small  one.  It  is  conceded  on  all  sides  at 
present  that  fertility  is  due  not  alone  to  the  chemical  character  of  the 
soil,  but  also  to  other  conditions  which  are  quite  as  influential,  such  as, 
the  physical  state,  the  bacterial  and  fungous  flora  and  the  presence  or 
absence  of  toxic  substances.  A  study  of  the  mycologic  flora  of  the  soil 
can  only  be  pursued  satisfactorily  by  those  who  have  been  trained  in 
cultural  methods. 

Then  too  the  study  of  plant  diseases  and  animal  diseases  rests  funda- 
mentally upon  technical  mycologic  laboratory  methods.  The  alarm- 
ing increase  of  plant  diseases  has  attracted  a  larger  and  ever  growing 
number  of  young  men  into  the  study  of  bacteriology  and  fungology. 
There  seem  to  be  unlimited  opportunities  for  such  carefully  trained  men 
and  women  to  get  profitable  employment  in  health  bureaus,  manufac- 
turing plants,  agricultural  experiment  stations,  and  as  plant  doctors 
stationed  in  our  larger  towns  and  cities,  ready,  as  a  medical  doctor  is 
ready,  to  give  for  a  monetary  consideration  expert  advice  and  treatment. 
Lastly,  there  are  chances  for  men  and  women  trained  in  technical 
mycology  to  become  professors,  or  teachers,  of  the  subject  in  our  col- 
leges and  agricultural  high  schools.  Such  trained  specialists  can  help 
to  increase  the  crop-producing  capacity  of  our  farms  by  eliminating 
the  prevalent  diseases,  which  reduce  seriously  the  farmers'  profits. 
Such  specialists  are  conservationists  in  the  truest  sense  of  the  term. 


PREFACE  Vll 

The  author,  with  great  pleasure,  thanks  the  following  persons  for 
suggestive  help  in  the  preparation  of  the  text-book:  Professor  J.  C. 
Arthur  read  the  proof  of  the  chapter  on  the  rust  fungi;  Prof.  D.  H. 
Bergey  of  the  University  of  Pennsylvania  the  pages  dealing  with 
laboratory  methods.  Prof.  Mel  T.  Cook  and  his  associates  J.  C. 
Helyar  and  C.  A.  Schwarze  of  the  New  Jersey  Agricultural  Experiment 
Station,  New  Brunswick,  read  the  galley  proofs  throughout  and  made 
valuable  suggestions.  Dr.  J.  S.  Hepburn  read  the  pages  dealing  with 
bio-chemistry,  Messrs.  H.  R.  Fulton  and  Donald  Reddick  also  made 
valuable  suggestions  as  to  the  arrangement  of  the  contents  of  the  book, 
while  Prof.  L.  R.  Jones  and  Dr.  C.  L.  Shear  furnished  illustrations  for 
reproduction  in  the  text.  Prof.  A.  H.  Reginald  Buller  of  the  University 
of  Manitoba  gave  permission  to  use  five  illustrations  in  his  book, 
Researches  on  Fungi. ' '  The  au thor  desires  to  express  his  thanks  for  the 
uniform  courtesy  of  members  of  the  firm  of  P.  Blakiston's  Son  &  Co., 
especially  to  Mr.  C.  V.  Brownlow,  whose  unfailing  interest  has  done 
so  much  to  forward  the  publication  of  the  work. 

J.  W.  H. 


CONTENTS 
PART  I.     MYCOLOGY 

Page 

CHAPTER  I. — General  Statement  and  Classification i 

CHAPTER  II.— Slime  Moulds  (Myxomycetes) 7 

CHAPTER  III.— The  Bacteria  in  General 21 

Name;  Size;  Locomotion;  Cell  Division  and  Reproduction;  Photogens; 

Chromogens;  Thermogens;  Aerobism  and  Anaerobism. 

CHAPTER  IV.— Classification  of  Bacteria •     28 

According   to   Nutrition;   Prototrophic   Bacteria;   Metatrophic   Bacteria; 

Paratrophic  Bacteria;  Systematic  Account  of  the  Bacteria;  Bibliography. 

CHAPTER  V. — Characteristics  of  the  True  Fungi 42 

CHAPTER  VI. — Histology  and  Chemistry  of  Fungi 52 

Histology;  Cell  Contents;  Colors;  Physiology;  Enzymes;  Classification  of 

Enzymes  in  Fungi;  Chemotaxis. 
CHAPTER  VII.— General  Physiology  of  Fungi 61 

Influence  of  Light;  Luminosity;  Liberation  of  Spores. 
CHAPTER  VIII.— Ecology  of  Fungi 69 

Saprophytes   and    Parasites;    Sclerotia;    Galls;    Habitats;    Xerophytism; 

lachen  Fungi. 
CHAPTER  IX.— Fossil  Fungi  and  Geographic  Distribution 82 

Fossil  Fungi;  Geographic  Distribution;  Habitats  of  Lichens;  Distribution  of 

Chestnut  Blight;  Laboulbeniaceae;  Family  Clathraceae. 
CHAPTER  X. — Phylogeny  of  Fungi ^9 

CHAPTER  XL— Mould  Fungi '        '     ^^ 

Order  Zygomycetales;  Sexual  Reproduction;  Spores  and  Sporangia;  Fer- 
mentation; Key  to  Families  of  the  Order  Zygomycetales;  Mucoracese; 
I^Iortierellacea;;  Choanephoracea;;  Chaetocladiacea;;  Piptocephalidaceae; 
Entomophthoraceae;  Bibliography. 

CHAPTER  XII.— Oospore-producing  Algal  Fungi 107 

Sexual  Reproduction;  Haploid  and  Diploid  State;  Key  to  Families;  Mono- 
blepharidaces;  Saprolegniaceae;  Peronosporaceae;  Generic  Key  to  Family 
Peronosporaceee. 

ix' 


X  CONTENTS 

Page 

CHAPTER  XIII.— OoMYCETALES  (Continued) ii6 

Chytridiaceae;  Ancyclistaceae;  Bibliography. 

CHAPTER  XIV.— Higher  Fungi 120 

Ascomycetales;  Sexuality,  Claussen  and  Harper;  Life  Cycle;  Bibliography. 

CHAPTER  XV. — Sac  Fungi  in  Particular  (Yeasts,  etc.)      131 

Endomycetaceae,  Exoascaceae;  Saccharomycetaceas;  Yeasts,  cells  and  fer- 
mentation, etc.;  Systematic  Position. 

CHAPTER  XVI.— Sac  Fungi  (Continued) 143 

Gymnoascaceae;  Aspergillaceae;  Elaphomycetaceae;  Terfeziaceae;  Tuberaceae 
(TruflBes) ;  Myriangiaceae. 

CHAPTER  XVIL— Mildews  and  Related  Fungi 154 

Erysiphaceae  (Mildews);  Perisporiaceae;  Microthyriaces;  Hypocreaceae; 
Dothideaceae;  Sordariaceae;  Chaetomiaceae;  Sphaeriaceae;  Valsaceae;  Melo- 
grammataceae;  Xylariaceae;  Hysteriaceae;  Phacidiaceae;  Pyronemaceae; 
Ascobolaceae;  Pezizaceae;  Helotiaceae;  Mollisiaceae;  Geoglossaceae;  Helvel- 
laceae;  Cyttariaceae;  Rhizinaceae;  Phylogeny  of  Ascomycetales;  General 
Bibliography. 

CHAPTER  XVIII.— Basidia-bearing  Fungi  (Smuts) 177 

Key  to  Suborders;  Ustilaginaceae  (Smuts);  Bibliography  of  Smuts. 

CHAPTER  XIX.— Rust  Fungi 187 

General  Structure;  Forms;  Life  Cycles;  Cytology;  Phylogeny;  Endophyl- 
lacese;  Coleosporiaceae;  Pucciniacese;  Bibliography  of  Rusts;  Auriculariaceae; 
Tremellaceae  (Trembling  Fungi). 

CHAPTER  XX.— Fleshy  and  Woody  Fungi 218 

Cytology;  Dacryomycetaceae;  Exobasidiaceae;  Hypochnaceae;  Thele- 
phoraceae;  Clavariaceae;  Hydnaceae;  Polyporaceae;  Manuals. 

CHAPTER  XXI.— Mushrooms  and  Toadstools 231 

Agaricaceae;  Development  of  Fruit  Bodies;  Cultivation  of  Mushrooms; 
Chemistry  and  Toxicology  of  Mushrooms;  Gasteromycetes;  Hymeno- 
gastraceae;  Tylostomaceae;  Lycoperdaceae;  Nidulariaceae;  Key  to;  Sclero- 
dermacese;  Sphserobolaceae;  Phallomycetes;  Development  of  Carrion  Fungi; 
Clathraceae;  Phallaceae;  Bibliography  of  Eubasidii. 

CHAPTER  XXII. — Fungi  Imperfecti  (Deuteromycetes) 258 

General  Characters;  Systematic  Position;  Sphaeropsidales ;  Melanconiales; 
Hyphomycetales. 


PART  II.     GENERAL  PLANT  PATHOLOGY 


CHAPTER  XXIII. — General  Consideration   of   Plant  Diseases  .    .    .271 
Etiology;  Predisposing  Causes;  Determining  Causes;  Physical  Character  of 
Soil;  Climatic  and  Meteorologic  Factors,  Effect  of  Smoke,  etc.;  Trauma- 
tism; Animate  Agents  of  Disease;  Insects. 


CONTENTS  XI 

Page 

CHAPTER  XXIV. — Plants  as  Disease  Producers,  Epiphytotism,  Prophy- 
laxis     298 

Vegetal  Agents  of  Disease;  Parasitic  Flowering  Plants;  Fungous  Organisms 
as  the  Cause  of  Disease;  Mechanic  Injuries;  Injuries  Due  to  Meteorologic 
Causes;  Infection;  Incubation;  Duration  of  Disease;  Dissemination  of 
Fungi;  Epiphytotisms  (Epidemics);  Prophylaxis. 

CHAPTER  XXV.— Practical  Tree  Surgery 319 

Preventive  Measures;  Character  of  Work;  Cavity  Treatment;  Mixing  and 
Placing  the  Cement;  Metal-covered  Cavities;  Guying. 

CHAPTER  XXVI.— Internal  Causes  of  Disease .^26 

Enzymes;  Panaschiering;  Calico;  Nutritive  Disturbances;  Mutations;  Mal- 
formations and  Monstrosities;  Graft  Hybrids;  Chimaeras. 

CHAPTER  XXVII. — Classification  of  Abnormalities 331 

CHAPTER  XXVIII. — Symptoms  of  Disease  (Symptomatology) 341 

Symptoms  of  Disease;  Discolorations;  Shot-holes;  Wilting;  Necrosis, 
Dwarfing;  Hypertrophy;  Replacement;  Mummification;  Alteration  of 
Position;  Destruction  of  Organs;  Excrescences  and  Malformations; 
Exudations;  Rotting;  Bibliography  of  Diseases  in  General. 

CHAPTER  XXIX.— Pathologic  Plant  Anatomy 354 

Restitution;  Hypoplasia;  Metaplasia. 

CHAPTER  XXX. — Pathologic  Plant  Anatomy  (Continued) 364 

Hypertrophy;  Excrescences;  Intumescences;  Callous  Hypertrophy;  Ty- 
loses; Gall  Hypertrophies;  Hyperplasia;  Homooplasia;  Heteroplasia; 
Callus;  Conditions  of  Callous  Formation;  Wound  Wood;  Wound  Cork. 

CHAPTER  XXL— Galls 384 

Kinds  of  Galls;  Cataplasms;  Histology  of  Cataplasms;  Histology  of  Galls. 
Cecidial  Tissue  Forms;  Bibliography  of  Galls. 

CHAPTER  XXXII.^ — Mechanic  Development  of  Pathologic  Tissues  . .  403 
General  Consideration;  Bibliography  of  Developmental  Mechanice,  Sug- 
gestions to  Teachers  and  Students. 


PART  III.     SPECIAL  PLANT  PATHOLOGY 


CHAPTER  XXXIIL— Specific  Diseases  OF  Plants 411 

General  Statement;  Principal  Publications;  List  of  Common  and  Important 
Diseases  of  Economic  Plants  in  "the  United  States  and  Canada  Arranged 
according  to  Host  Plants. 

CHAPTER  XXXIV. — Detailed  Account  of  Specific  Diseases  of  Plants  .  475 
Alfalfa  to  Grape. 

CHAPTER  XXXV.— Detailed    Account    of    Specific    Plant    Diseases 

(Continued) 517 

Hemlock  to  Wheat. 


Xll  CONTENTS 

Page 
CHAPTER  XXXVI. — Non-parasitic,  or  Physiologic  Plant  Diseases..  .  564 
Classification;  Stag-head;  Root  Asphyxiation;  Desiccation;  Water-logging; 
Oidema;  Frost  Necrosis;  Apple  Fruit  Spots;  Water-core  of  Apple;  Die- 
back,  or  Exanthema;  Mottle-leaf;  Curly-top  of  Sugar  Beets;  Peach  Yel- 
lows; Tip-burn  of  Potato;  Leaf -casting;  Curly-dwarf  of  Potato;  Bean 
Mosaic;  Mosaic  of  Tobacco;  Bibliography. 


PART  IV.     LABORATORY  EXERCISES  IN  THE 
CULTURAL  STUDY  OF  FUNGI 

CHAPTER  XXXVIL— Laboratory  and  Teaching  Methods 581 

Introductory  Remarks;  Lesson  i,  Micrometry;  Lesson  2,  Plugging  Test- 
tubes,  etc.;  Lesson  3,  Microscopic  Study  of  Culture  Material;  Stains; 
Lesson  4,  Liquid  Nutrient  Solutions;  Lesson  5,  Potatoes  as  Medium;  Lesson 
6,  Solid  Vegetable  Substances;  Lesson  7,  Plant  Juices;  Lesson  8,  Milk,  Beer- 
wort;  Lesson  9,  Bouillon;  Lesson  10,  Eggs;  Lesson  11,  Nutrient  Gelatin; 
Lesson  12,  Agar-Agar;  Lesson  13,  Various  Nutrient  Agars;  Lesson  14, 
General  Directions  for  Making  Plant  Agars;  Lesson  15,  Potato  Juice  Agar; 
Lesson  16,  Starch  Agar;  Lesson  17,  Culture  Media  for  Nitric  Organisms; 
Lesson  18,  Standardization  of  Culture  Media;  Lesson  19,  Germination 
Studies;  Lesson  20,  Counting  of  Yeasts  and  Bacteria;  Lesson  21,  Cultiva- 
tion of  Yeasts  on  Gypsum  Blocks,  Method  of  Pouring  Plates,  Streak 
Method;  Lesson  22,  Isolation  of  Fungi;  Lesson  23,  Water  Analysis;  Lesson 
24,  Methods  of  Identification;  Lesson  25,  Plate  Counter;  Lesson  26,  Sys- 
tematic Bacteriology;  Lesson  27;  Scheme  for  the  Study  of  Bacteria;  Lesson 
.  2.8,  Detailed  Study  of  Bacteria;  Lesson  29,  Directions  for  the  Study  of 
Pathogenic  Fungi. 

CHAPTER  XXXVIII. — Laboratory  and  Teaching  Methods  (Continued)  643 
Lesson  30,  Inoculation  Experiments;  Lesson  31,  Do.;  Lesson  32,  Do.; 
Lesson  ^^,  Do.;  Lesson  34,  Do.;  Lesson  35,  Experiments  with  Artificial 
Wounding  of  Plants;  Lesson  36,  Gas  Injuries;  Lesson  37,  Enzyme  Diseases; 
Lesson  38,  Study  of  Mistletoe;  Lesson  39,  Wire  Worms  in  Plants;  Lesson  40, 
Relation  of  Light  to  Pathogenic  Conditions;  Lesson  41,  Withering,  or  Wilt- 
ing of  Plants;  Lesson  42,  Methods  of  Sectioning,  Celloidin,  Paraffin; 
Lesson  43,  Freezing  and  Cutting  of  Material;  Lesson  44,  Use  of  Drawing 
and  Projection  Apparatus,  Drawing  Methods;  Lesson  45,  Suggestions  to 
Teachers  and  Students;  Lesson  46,  Content  of  Field  Trips  and  Excursions. 

APPENDIX  I.— Fungicides 669 

Bordeaux  Mixture,  etc. 

APPENDIX  II.— Spray  Calendar 680 

APPENDIX  III. — Antisepsis  and  Disinfection  ............  692 

Preservation  of  Woods. 


CONTENTS  Xlll 

Page 

APPENDIX  IV. — Culture  of  Mushrooms 693 

APPENDIX  V. — Synopsis  of  Families  and  Principal  Genera  of  Myxo- 

GASTRALES 693 

APPENDIX  VI. — Key  for  the  Determination  of  Species  of  Mucor   .    .    .   695 
APPENDIX  VII. — Keys  for  the  Determination  of  Species  of  Asper- 
gillus and  Penicillium 702 

APPENDIX  VIII. — Keys  to  the  Genera  of  the  Erysiphace^ 721 

APPENDIX  IX.— Collection  and  Preservation  of  Fleshy  Fungi   .    .    .726 
APPENDIX  X. — List  of  Keys  to  Fleshy  Fungi  and  Selected  Keys  of 

Fleshy  Fungi 729 

APPENDIX  XI.— Key  to  Agaricace^ 732 

Index 753 


PART  I 
MYCOLOGY 

CHAPTER  I 
GENERAL  STATEMENT  AND  CLASSIFICATION 

The  lower  plant  organisms  which  concern  the  mycologist,  or  the 
student  of  the  fungi,  may  be  considered  in  a  general  sense,  or  in  a 
narrow  way.  A  general  definition  would  include  all  those  thallo- 
phytes,  or  lower  cellular  plants  (lacking  archegonia),  which  are 
destitute  of  chlorophyll  and  in  its  absence  become  dependent,  with 
the  exception  of  the  prototrophic  bacteria,  upon  extraneous  supplies 
of  organic  food,  either  Hving  or  dead.  This  broad  definition  compels 
the  mycologist  to  study  the  slime  moulds,  the  bacteria  and  the  true 
fungi,  both  as  to  their  morphology  and  their  physiology.  He  finds  on 
such  study,  that  broadly  speaking,  there  are  similarities  of  structure 
and  function  in  both  groups  of  dependent  plants,  in  fact,  he  finds  that 
the  function  of  these  plants  is  connected  with  cell  organization  and 
structure  and  vice  versa.  With  this  clearly  in  view,  the  mycologist 
finds  that  he  has  to  deal  with  three  distinct  classes  of  chlorophylless 
plants,  namely: 

Class  Myxomycetes  (slime  moulds). 

Class  Schizomycetes  (bacteria). 

Class  Eumycetes  (true  fungi). 

The  classification  of  these  colorless  (chlorophylless)  lower  plants 
has  been  elaborated  in  recent  years  with  considerable  detail  by  various 
authors,  30  that  the  broad  fundamental  facts  both  of  taxonomy  and 
phylogeny  are  known  fairly  well,  but  much  remains  to  be  done  along 
the  classificatory  fines,  especially,  since  the  life  histories  of  many 
of  the  bacteria  and  fungi  are  incompletely  known.  It  may  be 
many  years  before  a  generally  acceptable  nomenclature  and  classifi- 
cation win  be  an  accompHshed  fact.  The  choice  of  a  classification  by 
any  worker  in  mycology  depends  largely  on  his  training  and  bias  and 
on  his  detailed  study  of  the  various  groups.  No  two  men  would 
entirely  agree  as  to  which  was  the  best  sequence  to  adopt  in  a  system- 
atic treatment  of  the  different  forms.    The  classification  adopted  in  this 

fHOPERTf^UBRARY 
N.  C.  State  College 


2  MYCOLOGY 

treatise  is  based  on  that  of  Engler  and  Gilg,  as  published  in  the  seventh 
illustrated  edition  of  "Syllabus  der  PflanzenfamiUen,"  Berlin,  1912,  and 
on  that  of  Wettstein  in  his  "Handbuch  der  Systematischen  Botanik," 
Leipzig  and  Vienna,  191 1.  Where  consistent,  the  classificatory  sys- 
tems of  these  two  books  are  harmonized  and  any  departures  which  the 
student  will  find  from  the  taxonomic  arrangements  of  Engler  and 
Wettstein  have  been  made  to  simplify  them  by  the  omission  of  cer- 
tain group  names,  or  to  bring  the  two  systems  into  line  with  the  facts 
as  at  present  known.  The  author  has  not  hesitated  to  make  changes, 
where  from  his  experience  as  a  teacher,  he  has  found  it  best  to  make 
such  alterations,  especially  where,  for  example,  Wettstein  uses  Ordnung 
and  Engler  Reihe  for  the  same  classificatory  group,  and  where  in 
American  usage  order  and  family  are  used.  Then,  too,  the  author  has 
found  it  convenient  to  replace  the  name  of  a  family,  or  order,  as  given 
by  Engler  for  one  used  by  Wettstein,  or  some  other  author,  where  such 
replacement  is  recommended  by  American  usage,  or  where  etymolog- 
ically  the  name  is  more  suggestive  of  the  character  of  the  group,  and, 
therefore,  best  for  the  use  of  students  who  do  not  expect  to  follow  out 
the  intricacies  of  any  system  of  classification.  As  the  statements  and 
views  of  Engler  and  Wettstein  are  generally  dependable  and  as  their 
classification  is  founded  on  long  experience,  as  systematic  botanists, 
it  will  be  found  that  with  respect  to  the  larger  subdivisions  of  the 
fungi  their  classifications  are  remarkably  harmonious.  The  attempt 
has  been  made  in  the  pages  that  follow  to  simphfy  for  student  use 
the  facts  of  classificatory  importance  and  while  the  groups  are  ar- 
ranged in  lineal  sequence,  it  should  be  explained  that  true  relationship 
is  expressed  better  by  a  family  tree  with  main  trunk,  larger  and  smaller 
branches.  It  will  be  noted  that  the  arrangement  of  the  famiUes,  as 
given  in  the  two  systematic  works  above  mentioned,  are  sometimes 
reversed.  The  simple  groups  are  given  first  place,  followed  by  the 
more  complex. 

CLASS  I.  MYXOMYCETES. 
ORDER  I.  ACRASIALES. 

Family  i.  Guttulinaceae. 
Family  2.  Dictyosteliaceae. 

ORDER  II.  PHYTOMYXALES. 

Family  i.  Plasmodiophoraceae. 


GENERAL   STATEMENT   AND   CLASSIFICATION 

ORDER  III.  MYXOGASTRALES. 

Suborder.  Exospore^. 

Family  i.  Ceratiomyxacese. 
Suborder.  ENDOspoREiE. 

Family  2.  Physaraceae. 

Family  3.  Didymiaceag. 

Family  4.  Stemonitaceae. 

Family  5.  Brefeldiaceae. 

Family  6.  Cribrariaceae. 

Family  7.  Liceacese. 

Family  8.  Tubiferaceae. 

Family  9.  Reticulariaceae. 

Family  10.  Trichiaceae. 

CLASS  II.  SCHIZOMYCETES. 
ORDER  I.  EUBACTERIALES. 

Family  i.  Coccaceae. 

Family  2.  Bacteriaceae. 

Family  3.  Spirillaceae. 

Family  4.  Phycobacteriaceae  (Chlamydobacteriaceae). 

Family  5.  Thiobacteriaceae  (Beggiatoaceae). 

Family  6.  Actinomycetaceje  (position  doubtful). 

ORDER  II.  MYXOBACTERIALES. 
Family  i.  Myxobacteriaceae. 

CLASS  III.  EUMYCETES. 

Subclass.  Phycomycetes. 

ORDER  I.  ZYGOMYCETALES. 

Family  i.  Mucoraceae. 

Family  2.  Mortierellaceae. 

Family  3.  Choanephoraceae. 

Family  4.  Chaetocladiaceae. 

Family  5.  Piptocephalidaceae. 

Family  6.  Entomophthoraceae. 


MYCOLOGY 

ORDER  II.  OOMYCETALES. 

Family  i.  Monoblepharidacejr. 
Family  2.  Saprolegniaceae. 
Family  3.  Peronosporaceae, 
Family  4.  Chytridiaceae. 
Family  5.  Ancyclistaceas. 

Subclass.  Mycomycetes. 

ORDER  III.  ASCOMYCETALES. 
Suborder  A.  Protoasciine^. 
Family  i.  Endomycetaceae. 
Family  2.  Exoascaceae. 

Suborder  B.  Saccharomycetiine;1': 
Family  i.  Saccharomycetaceas. 


Suborder  C.  Plectasciine^. 

Family  i. 
Family  2. 
Family  3. 
Family  4. 
Family  5. 

Gymnoascaceae. 

Aspergillaceje. 

Elaphomycetaceae. 

Terfeziaceae. 

Tuberaceae. 

Suborder  D.  Perisporiine^. 

Family  i. 
Family  2. 
Family  3. 

Erysiphaceae. 

Perisporiaceae. 

Microthyriaceae. 

Suborder  E.  Pyrenomycetiine^. 
Family  i.  Hypocreaceae. 
Family  2.  Dothideaceae. 
Family  3.  Sordariaceae. 
Family  4.  Chaetomiaceae. 
Family  5.  Sph^eriacea?. 
Family  6.  Valsaceae. 
Family  7.  Melogrammataceae. 
Family  8.  Xylariaceae. 


GEN-ERAL    STATEMENT    AND    CLASSIFICATION 

Suborder  F.  Discomycetiine^, 
Family  i.  Hysteriaceae. 
Family  2.  Phacidiaceae. 
Family  3.  Pyronemaceae. 
Family  4.  Ascobolaceae. 
Family  5.  Pezizaceae. 
Family  6.  Helotiaceae. 
Family  7.  Mollisiaceae. 
Family  8.  Celidiaceae. 
Family  9.  Patellariaceas. 
Family  10.  Cenangiaceas. 

Suborder  G.  HELVELLiiNEiE. 
Family  i.  Geoglossaceae. 
Family  2.  Helvellaceae. 
Family  3.  Cyttariaceae. 
Family  4.  Rhizinaceae. 

Suborder  H.  Laboulbeniine^. 
Family  i.  Peyritschiellaceae. 
Family  2.  Laboulbeniaceae. 
Family  3.  Zodiomycetaceae. 

ORDER  IV.  BASIDIOMYCETALES. 
Suborder.  Hemibasidiine^. 
Family  i.  Ustilaginaceas. 
Family  2.  Tilletiaceas. 

Suborder.  Uredine^.    (Usually  Order  Uredinales). 
Family  i.  Endophyllaceae. 
Family  2.  Melamsporaceae. 
Family  3.  Pucciniaceae. 
Family  4.  Coleosporaccce. 

Suborder.  Auricularin^. 
Family  i.  Auriculariaceae. 
Family  2.  Pilacraceae. 

Suborder.  Tremellin^. 
Family  i.  Tremellaceae. 


6  MYCOLOGY 

Suborder.  Eubasidiine^. 

A.  Hymenomycetes. 
Family  i.  Dacryomycetaceae. 
Family  2.  Exobasidiaceae. 
Family  3.  Hypochnaceae. 
Family  4.  Thelephoraceae. 
Family  5.  Clavariaceas. 
Family  6.  Hydnaceae. 
Family  7.  Polyporaceae. 
Family  8.  Agaricacese. 

B.  Gasteromycetes. 
Family  i.  Hymenogastraceae 
Family  2.  Tylostomaceae. 
Family  3.  Lycoperdaceae. 
Family  4.  Nidulariaceae. 
Family  5.  Sclerodermacese. 
Family  6.  Sphaerobolacese.  - 

C.  Phallomycetes. 
Family  i.  Clathraceae. 
Family  2.  Phallaceae. 

Fungi  Imperfecti  (Deuteromycetes). 
ORDER  I.  SPH^ROPSIDALES,  with  4  families. 
ORDER  II.  MELANCONIALES,  with  i  family. 
ORDER  III.  HYPHOMYCETALES,  with  4  families. 

The  above  classification  has  been  given  in  outline  with  the  object 
of  presenting  to  students  the  information  which  is  requested  frequently 
of  the  professor  in  the  class  room.  A  detailed  presentation  of  the  spe- 
cial morphology,  histology,  embryology  and  taxonomy  of  each  group 
will  be  given  in  the  pages  which  follow,  omitting  matters  concerning 
pathology  and  practice.  A  separate  section  of  this  treatise  will  be 
devoted  to  the  consideration  of  fungous  diseases  of  plants  and  their 
treatment. 


CHAPTER  II 

SLIME  MOULDS  (MYXOMYCETES) 

CLASS  I.     MYXOMYCETES 

Considerable  attention  has  been  given  in  recent  years  to  the  sHme 
moulds  on  account  of  their  biologic  interest,  taxonomic  relationship 
and  disease-producing  forms.  As  organisms,  they  have  been  bandied 
about.  They  have  been  claimed  by  zoologists  and  botanists  alike, 
for  in  certain  stages  of  their  life  cycle  they  strongly  suggest  the  protozoa, 
such  as  the  amoeba.  Perhaps  on  account  of  this  uncertainty  one  would 
be  justified  in  placing  the  slime  moulds  in  the  class  Protista  of  Haeckel, 
which  group  was  intended  to  include  all  such  primitive  organisms 
which  naturalists  have  been  unable  to  put  satisfactorily  either  in  the 
animal,  or  the  vegetable  kingdoms,  but  which  partake  of  the  nature  of 
both  the  animal  and  the  plant  phylae.  Hence  we  would  have  as  a 
tentative  arrangement 

Protista 
/  \ 

/  \ 

Protozoa  Protophyta 

where  the  Protista  represent  the  primitive  stock  of  organisms  which 
have  given  rise  to  simple  animals  on  the  one  hand,  or  primitive  plants 
on  the  other. 

Fries  and  some  of  his  predecessors  considered  that  the  slime  moulds 
were  puffballs  (Gasteromycetes)  and  the  expression  of  this  view  is 
suggested  in  the  name  Myxogastres  given  them  by  Fries  in  1833. 
Wallroth  in  1836  viewing  them  as  related  to  the  fungi  termed  them 
MYXOMYCETES.  De  Bary,  the  German  botanist,  in  1858,  impressed 
by  their  closer  relationship  with  the  animal  world,  called  them  Myce- 
TOZOA.  Zo'pi  in  1885  describes  them  as  Die  Pilzthiere  and  Rostafinski, 
a  pupil  of  De  Bary,  working  under  his  supervision  in  an  elaboration 
of  a  monograph  of  these  organisms,  calls  them  Mycetozoa.  We,  there- 
fore, are  limited  by  strict  priority  to  adopt  the  name  Myxogastres 
for  them;  but  there  are  valid  reasons  why  the  name  Myxomycetes 

7 


8  MYCOLOGY 

should  be  used.  One  of  the  strongest  arguments  is  thai  if  we  consider 
them  as  plants  they  belong  to  the  phylum  of  the  fungi  and  hence  this 
name  Myxomycetes  aligns  itself  with  Schizomycetes  and  Eumycetes 
generally  adopted  for  the  other  groups  of  fungi.  It  conduces  to  clarity 
and  simplification  of  classification  to  adopt  the  name  of  Wallroth  for 
the  class  of  organisms  incapable  of  an  independent  existence,  being 
destitute  of  chlorophyll  and  mainly  saprophytic.  The  older  name  is 
retained,  however,  as  the  name  of  the  third  order  of  Myxomycetes, 
hence  there  should  be  little  criticism  of  the  view  taken  above.  The 
Myxomycetes  (Mycetozoa,  Schleimpilze,  Pilztiere,  Slime  Moulds)  are 
chlorophylless  organisms.  Their  vegetative  condition  is  known  as  a 
Plasmodium  which  is  a  naked  streaming  mass  of  protoplasm.  Repro- 
duction is  by  means  of  spores  produced  as  exospores,  or  endospores, 
the  latter  in  sporangia,  gethalia,  or  plasmodiocarps.  The  spores  give 
rise  to  amceboid  cells  or  flagellate  swarmers  which  unite  later  to  form 
the  Plasmodium,  or  develop  directly  into  the  plasmodium. 

ORDER  I.  ACRASIALES.—The  members  of  this  order  live  on 
the  excrements  of  animals  and  on  the  decaying  parts  of  plants.  They 
commence  their  development  with  the  escape  of  an  amoeboid  body 
from  the  walls  of  the  spore  and  then  move  about  by  creeping  move- 
ments, never  assuming  ciHa  for  locomotion.  The  amoeboid  cells  pile 
up  on  one  another  without  coalescing  to  form  what  has  been  called  an 
aggregate  plasmodium,  and  they  remain  distinct,  and  artificially  sepa- 
rable, though  closely  packed  together  until  the  fructification  forms, 
when  they  rise  above  the  substratum  and  form  bodies  of  definite 
shape.  Every  one,  or  the  majority  of  these  definitely  arranged  amoe- 
boid bodies,  becomes  a  spore  covered  by  a  dehcate  membrane  and  of  an 
average  size  of  5  to  10  m-  These  heaps  of  spores  resemble  the  sporangia 
of  the  true  shme  moulds,  but  there  is  no  distinct  sporangial  wall, 
the  spores  being  held  together  by  a  structureless  enveloping  substance. 
The  plants  of  this  group  are  saprophytes.  Gutkdina  rosea  lives  on 
decaying  wood  in  Europe.  Dictyosteliuni  mucoroides  is  frequent  on 
old  dung,  while  Acrasis  granulata  is  found  on  old  yeast  cakes.  Poly- 
sphondylium  violacewn  occurs  in  southern  Europe  on  manure. 

ORDER  II.  PHYTOMYXALES.— The  shme  moulds  of  this  order 
are  parasites  which  live  in  the  cells  of  higher  plants.  The  plasmodium 
is  limited  by  the  cell  walls  of  the  host  plants,  and  has  its  origin  in 
amoeboid  cells  which  enter  and  infest  the  host  cells,  resulting  in  a 


SLIME    MOULDS    (mYXOMYCETES)  9 

stimulation  of  the  host  to  form  gall-hke  swelUngs.  The  whole  Plas- 
modium is  later  transformed  by  division  into  a  greater  or  less  number 
of  parts,  which  become  surrounded  by  membranes  to  form  spores. 
The  spores  are  free  in  the  cells  of  Plasmodiophora,  while  in  SorosphcBra 
and  in  Tetramyxa  they  are  clumped,  and  surrounded  by  a  delicate 
membrane.     The  order  includes  a  single  family: 

Family  i.  Plasmodiophorace^. — ^The  characters  of  this  family  are 
coincident  with  those  of  the  class  as  given  above.  The  family  includes 
four  genera  distinguished  as  follows: 

A.  Spores  distinct  from  each  other,  irregularly  aggregated  and  fiUing 
the  host  cells. 

{a)  Spores  regular  in  shape,  spheric,     (i)  Plasmodiophora. 

(b)  Spores  irregularly  shaped,  rod-like,  or  angular.     (2)  Phytomyxa. 

B.  Spores  united  into  clumps  inclosed  by  a  delicate  membrane. 
{a)  Spores  united  in  groups  of  four  each.     (3)  Tetramyxa. 

(b)  Spores   in   greater  number,    united  into  hollow   spheres.     (4) 
Sorosphcera. 

The  genus  Plasmodiophora  comprises  possibly  three  species  found 
in  Europe  and  America.  They  are  parasites  in  the  parenchyma  cells 
of  the  cortex  of  the  roots  of  the  higher  plants,  where  they  produce 
gall-like  swellings.  The  plasmodium  fills  some  of  the  living  cells  of 
the  host.  The  spores  formed  subsequently  are  spheric  and  lie  free 
within  the  host  cells.  The  best  known  species  is  P.  brassicce  which 
is  the  cause  of  a  serious  disease  known  as  club  foot,  or  finger  and  toes 
(Fig.  i).  The  symptoms  of  the  disease,  the  relationship  of  host  and 
parasite,  will  be  described  in  a  subsequent  section  of  this  book.  Two 
other  species  have  been  described,  viz.,  P.  alni  in  the  roots  of  the  alder; 
and  P.  eleagni  in  the  roots  of  Eleagnus,  the  silverberry.  Considerable 
more  study  will  have  to  be  made  of  the  organisms  in  the  roots  of  the 
alder  and  silverberry  before  we  can  definitely  place  the  causal  organ- 
isms. Tentatively,  we  may  adopt  the  generally  accepted  view  of  the 
systematic  relationship  of  the  two  responsible  organisms  until  later 
investigation  either  proves  or  disproves  the  nature  of  the  parasites 
attacking  Alnus  and  Eleagnus. 

The  genus  Phytomyxa  is  represented  by  two  species  which  live  as 
parasites  in  the  roots  of  Hving  plants  and  cause  tuber-like  enlargements. 
The  Plasmodia  fills  the  host  cells,  and  later,  the  irregularly  shaped 


MYCOLUGY 


Pig.  I. — Club-root  of  cabbage,  Plasniodiophora  brassicce.  i,  Turnip  with  club- 
root;  2,  section  of  cabbage  root  with  parenchyma  cells  filled  with  slime  mould;  3, 
isolated  parenchyma  cell,  (v)  vacuole,  (0  oil-drops  in  Plasmodium,  (/>)  Plasmodium; 
4,  lower  cell  with  Plasmodium,  upper  cell  with  spores  developing;  5,  parenchyma 
cell  with  ripe  spores;  6,  isolated  ripe  spores;  7,  germinating  spores;  8,  myxamoeba. 
{Figs.  2-8,  after  Woronin  in  Soraucr,  Handbuch  der  PJlanzenkrankheiten,  1886,  p.  72.) 


SLIME    MOULDS    (mYXOMYCETES)  .  II 

spores  fill  the  infested  host  cells.  Two  species  have  been  described. 
The  nature  of  Ph.  leguminosanim  is  doubtful,  as  it  may  have  been 
•confused  with  one  of  the  stages  of  the  nodule-producing  bacteria, 
which  are  found  in  the  roots  of  leguminous  plants. 

The  parasitic  slime  mould,  Tetramyxa,  occurs  as  one  described 
species  Tetramyxa  parasitica,  which  lives  in  the  stems  and  flower  stalks 
of  water  plants,  as  Ruppia  rostellata,  where  it  causes  tubercles  0.5  to 
I  mm.  in  diameter.  Each  host  cell  contains  numerous  colorless  spores 
united  into  tetrads. 

SorosphcBra  is  represented  in  Germany  by  S.  veronica;  found  in  the 
stems  and  petioles  of  Veronica  hederifolia,  V.  triphylla  and  V.  chamce- 
drys.  The  cells  of  the  galls  are  swollen  and  filled  with  numerous 
spheric  or  ellipsoidal  brown  balls,  15  to  22  /x  in  diameter,  formed  of  a 
single  layer  of  spores  united  into  a  hollow  sphere  and  covered  externally 
by  their  pellicle. 

ORDER  III.  MYXOGASTRALES.— This  order  includes  the  true 
slime  moulds  which  are  non-parasitic,  but  live  on  decaying  organic 
material,  such  as  old  logs,  leaf  mould  in  the  forest,  compost  heaps, 
spent  tan  bark  and  other  organic  debris  in  the  fields,  woods,  and 
along  the  roadsides.  One  form  grows  over  the  grass  of  lawns  and 
smothers  the  grass  with  its  plasmodium  and  later  by  its  sporangia  and 
spores.  The  plasmodium  is  a  naked  mass  of  protoplasm  usually  of  a 
reticulate  structure  and  multinucleate.  It  arises  by  the  union  of  the 
myxamoeba  which  are  developed  from  the  flagellate  myxomonads  by 
the  loss  of  the  vibratile  flagella.  Such  a  plasmodium  is  known  as  a 
fusion  Plasmodium.^  It  usually  assumes  a  reticulate,  or  net-like, 
structure  and  currents  of  protoplasm  are  seen  flowing  along  the  strands 
of  greater  or  less  thickness  of  which  the  plasmodium  is  composed.  The 
central  portion  of  each  current  is  denser  and  moves  more  rapidly  than 
the  marginal  clearer  protoplasm.  Perhaps  we  are  justified  in  stating 
that  the  outer  protoplasm  is  the  ectoplasm  and  the  inner  granular 
cytoplasm  containing  food  substances  and  other  included  substances 
is  the  endoplasm.  For  some  time  the  plasmodium  may  flow  in  a  given 
direction  and  later  it  may  reverse  its  course,  moving  in  an  entirely 
opposite  direction.  The  color  of  the  plasmodium  difi"ers  in  different 
species,  as  the  following  table  will  show.  White  or  yellow  seem  to  be 
the  more  usual  colors. 

1  In  Lahyrinlhiila  Cicnkowskii  parasitic  in  Vauchcria  the  plasmodium  is  filamen- 
ous. 


12  .  MYCOLOGY 

Yellow Fiiligo  seplica. 

Orange TricJiia  scabra. 

White Pliysai'um.  cUipsoidcum. 

Lead-colored Crihraria  argillacea. 

Pink Enteridiv.m  splendens. 

Ruby-red , Hemitrichia  vesparum. 

Red Tubifera  ferruglnea. 

Scarlet Cribrarla  purpurea. 

Brown Tubifera  Casparyi. 

Violet Cribraria  violacea. 

The  movement  of  the  plasmodium  is  associated  with  the  incorpora- 
tion of  food.  The  yellow  plasmodium  of  Badhamia  utricularis  has 
been  most  carefully  studied  in  its  relation  to  a  food  supply.  It  can  be 
cultivated  on  such  woody  fungi  as  Stereum  hirsutum,  over  which  it 
extends,  devouring  by  enzyme  action  the  more  delicate  hyphae. 
Thus  nourished,  it  will  spread  over  the  moist  filter  paper  inside  of  the 
covering  bell  jar  until  I  have  seen  the  plasmodium  hanging  down 
like  stalactites  from  the  inner  top  of  the  bell  jar.  Such  a  captive 
Plasmodium  has  been  fed  by  the  writer  pieces  of  mushroom 
Agaricus  campestris.  Shaggymane,  Coprinus  comatus  and  beefsteak 
have  been  placed  on  the  surface  of  the  protoplasm  and  in  a  few  hours 
these  substances  have  been  found  in  advanced  stages  of  digestion. 
Cheese  is  reluctantly  invaded  and  is  more  refractory.  The  plas- 
modium is  responsive  to  changes  in  the  moisture  surroundings.  It 
moves  toward  a  more  abundant  water  supply.  It  is  hydrotropic. 
It  moves  against  a  current  of  water  and  is,  therefore,  rheotropic. 
When  highly  illuminated,  the  plasmodium  moves  away  from  the 
lighted  surface.  It  is  negatively  heliotropic.  If  there  is  a  sudden 
change  in  the  watery  environment,  the  plasmodium  will  become 
massed  into  a  cake-like  lump  in  which  form  it  remains  as  a  sclerotium, 
macrocyst,  or  phlebomorph,  if  the  substratum  loses  its  water  supply. 
In  the  sclerotial  condition,  the  writer  has  kept  a  plasmodium  for 
nine  months  on  a  plate  of  glass  placed  inside  of  a  laboratory  case 
in  an  absolutely  dry  condition.  It  was  started  into  activity  at  the 
end  of  this  period  of  rest  on  restoring  free  water  to  it  again,  and 
by  feeding  it  mushrooms,  it  was  kept  in  its  restored  activity  for 
several  weeks  beneath  a  bell  jar.  The  plasmodial  stage  may  be  pro- 
longed for  an  indefinite  period,  if  the  environmental  conditions  of 
temperature,  Hght,  moisture  and  food,  are  favorable.     The  writer  has 


SLIME    MOULDS    (m\^OMYCETES)  1 3 

kept  a  Plasmodium  in  a  streaming  condition  for  over  a  month  be- 
neath a  bell  jar.  Physarum  psitiacinuni,  which  inhabits  the  rotten 
stumps  of  old  trees,  appears  to  pass  a  year  as  a  plasmodium. 

The  early  stages  in  the  formation  of  the  sporangium  have  been  de- 
scribed in  Comatricha  oUusata.  When  the  fruiting  period  is  reaclifd, 
the  watery- white  plasmodium  issues  from  the  wood  crannies  and  spreads 
over  an  area  perhaps  half  an  inch  across.  The  plasmodium  is  seen  to 
concentrate  in  thirty  or  forty  centers  and  in  an  hour  or  two  each 
center  has  by  rhythmic  pulsation  of  the  protoplasm  risen  into,  a  pear- 
shaped  body  with  a  slender  base  and  an  enlarged  upper  portion.  The 
black  hair-Uke  stalk  has  grown  to  its  full  length  in  six  hours  and  on 
its  summit  is  borne  the  young  sporangium,  which  is  a  white  viscid 
globule  of  protoplasm.  A  pink  flush  now  begins  to  appear  in  the 
sporangium.  The  included  nuclei  are  like  those  of  the  plasmodium 
at  first,  but  later  as  spore  formation  proceeds  they  divide  mitotically. 
The  sporangia  of  the  different  slime  moulds  take  various  forms  which 
will  be  described  in  general  in  the  systematic  generic  keys  which 
follow.  They  may  be  either  symmetric  or  irregular  in  shape,  sessile  or 
stalked.  The  irregular  sessile  forms,  which  simulate  the  net-like 
appearance  of  the  streaming  protoplasm,  are  called  plasmodiocarps. 
When  the  fruit  body  is  fiat  and  cake-like  with  separating  walls  imper- 
fectly developed  it  forms  an  cethalium.  The  protoplasm  which  is 
left  on  the  substratum  and  dries  down  as  a  film-like  residuum  is  known 
as  the  hypothallus  (Figs.  2  and  3). 

The  changes  which  take  place  in  the  formation  of  spores  and 
capilhtium  have  been  minutely  studied  in  a  number  of  sUme  moulds. 
We  owe  much  to  R.  A.  Harper,  E.  W.  Olive  and  B.  O.  Dodge  in  America 
and  to  E.  Jahn  in  Germany  for  our  knowledge  of  these  processes.  The 
process  in  Didymium  melanospermum,  according  to  Harper,^  is  as 
follows:  The  spore  plasm  condenses  so  that  it  is  finely  granular  in  the 
peripheral  region  and  central  region  near  the  columella  and  foamy 
vacuolar  in  the  middle  zone.  The  capillitium  is  already  formed  before 
the  condensation  of  the  protoplasm  has  been  accomplished.  It  con- 
sists of  smooth  threads  which  pass  radially  outward  from  the  central 
dome-shaped  columellar  cavity  to  the  sporangial  wall.  The  threads 
of  the  capillitium  are  attached  at  their  ends.  The  protoplasm  is  in 
contact  with  these  threads  and  at  this  stage  the  nuclei  are  scattered 

1  Harper,  R.  A.:  Amcr.  Journ.  Rot.,  i:   127-144,  March,  1914. 


14 


MYCOLOGY 


rather  uniformly  through  the  spore  plasm  and  are  of  unequal  size. 
Vacuoles  are  formed  in  a  still  further  condensation  of  the  sporangial 
-protoplasm  and  each  of  these  apparent  vacuoles  is  pierced  by  a  capilli- 
tial  thread  which  runs  through  its  central  axis.  Droplets  of  water  are 
formed  along  the  capillitial  thread  as  a  still  further  evidence  of  water 
extrusion.  Cleavage  planes  now  appear  at  the  periphery  of  the  mass 
of  sporangial  protoplasm  and  progress  inwardly  toward  the  center. 
The  process  of  cleavage  parallels  the  extrusion  of  water  and  the  for- 
mation of  the  blocks  of  protoplasm  by  these  cleavage  lines  is  assisted 


Fig.  2. — -A,  B,  Comatricha  nigra.  A,  Sporangium,  natural  size;  B,  capillitium, 
20/1;  C,  E,  Stemonitis  fusca;  C,  sporangium,  natural  size;  D  and  E,  capillitia,  5/1, 
20/1;  F,  H,  Enerthema  papillatum,  F,  unripe;  G,  mature  sporangium,  lo/i;  H,  capil- 
litium, 20/1.  (C,  D,  after  nature.  A,  F,  G,  H,  after  Rostafinski;  B,  E,  after  de  Bary 
in  Die  natiirlichen  Pflatizenfamilien  I.  i,  p.  26.) 


by  the  presence  of  the  vacuoles.  The  splitting  up  of  the  irregular  blocks 
of  protoplasm,  which  have  the  nuclei  irregularly  distributed  through 
them,  proceeds  until  the  protoplasmic  blocks  arebinucleated,and  before 
this  the  nuclei  are  seen  in  various  stages  of  division  which  proceeds 
irregularly  in  Didymium,  while  in  Fuligo  the  division  of  the  nuclei  is 
simultaneous  in  a  particular  spore  sack.  The  plasma  membranes  of 
the  capillitial  openings  are  the  source  of  cleavage  furrows  to  even  a 
greater  degree  than  the  original  surface  plasma  membrane  of  the  spore 
sack  as  a  whole.  In  Fuligo  in  the  final  stages  of  spore  formation  the 
spore  plasm  is  condensed  about  the  nuclei,  but  in  Didymium,  the  ultimate 


SLIME   MOULDS    (mYXOMYCETES)  1$ 

result  of  the  progressive  cleavage  in  f urrowin,^  is  the  formation  of  uninu- 
cleated  rounded  spores.  They  he  packed  between  the  capillitial 
threads. 

Most  genera  of  slime  moulds  have  a  capiUitium  (Figs.  2  and  3) 
consisting  of  a  system  of  threads,  and  as  we  have  seen,  it  appears  be- 
fore the  spores  are  formed.  When  the  capiUitium  extends  from  the 
base  of  the  sporangium,  it  is  associated  with  a  columella  (Fig.  2).  It 
differs  widely  in  the  dififerent  genera  of  the  groups.  In  some  genera,  as 
Trichia  and  Arcyria,  the  capiUitium  consists  of  free  threads,  or  elaters. 
In  those  genera  in  which  calcium  carbonate  is  present  in  the  sporangia, 
it  is  found  in  the  capiUitium  usually  when  several  threads  meet  forming 
then  the  so-caUed  hme  knots.  In  Dictydimn,  purplish-red  granules 
are  imbedded  in  the  threads  of  the  false  capiUitium  and  are  known 
as  dictydin  granules.  The  formation  of  the  capiUitium  in  certain 
myxomycetes  has  been  investigated  by  Harper  and  Dodge.^  They 
find  that  the  capiUitium  is  formed  by  the  deposit  of  materials  in  the 
vacuoles  from  which  the  capiUitial  thread  is  formed  and  that  radiating 
threads  run  out  from  the  larger  granules  which  are  deposited  by  the 
process  of  intraprotoplasmic  secretion.  These  radiating  fibrUs  sug- 
gest rather  strongly  that  they  are  cytoplasmic  streams  which  are 
bringing  materials  for  the  formation  of  the  capillitial  wall  and  its  thick- 
enings which  are  laid  down  sometimes  as  spirals,  suggesting  that  the 
process  is  comparable  to  the  ordinary  processes  of  cell-waU  formation, 
but  along  internal  plasma  membranes,  rather  than  external.  The 
relation  of  the  fibrils  to  the  capillitial  granules  is  best  seen  where  a 
capiUitial  vacuole  runs  longitudinally.  Strasburger's  earher  observa- 
tions are  confirmed  by  the  recent  work  on  capiUitial  formation,  when 
he  described  the  capiUitium  of  Trichia  fallax  as  originating  in  vacuolar 
spaces  in  the  cytoplasm  which  elongate  and  take  on  the  tubular  form 
of  young  capillitial  threads,  while  the  formation  of  the  wall  and  spiral 
thickenings  are  due  to  the  deposition  of  granules  as  intraprotoplasmic 
secretions  consisting  of  microsomes  of  the  membranogenous  type. 
Where  the  capiUitial  threads  are  solid  they  may  be  called  stereone- 
mata;  where  hollow,  coelonemata. 

The  spores  are  discharged  from  the  sporangia,  and  if  they  find  a 
suitable  medium  in  which  to  grow,-  such  as  free  water,  they  give  rise  to 
swarm  cells,  as  amoeboid  bodies,  or  myxamoebse.     These  soon  acquire  a 

^Annals  of  Botany,  xxviii:   1-18,  January,  rQi4. 


I 6  MYCOLOGY 

.flagellum  at  the  anterior  end  and  creep  in  a  linear  form  with  the  flagellum 
extended  in  advance,  or  swim  about  in  the  water  with  a  dancing  move- 
ment occasioned  by  the  lashing  of  the  flagellum.  They  have  a  single 
nucleus  and  a  contractile  vacuole.  To  a  large  extent  they  feed  on 
bacteria  which  are  swallowed  by  pseudopodia  which  project  from  the 
posterior  end  of  the  cell.  The  swarm  cells  increase  rapidly  by  biparti- 
tion.  When  this  takes  place,  the  flagellum  is  first  withdrawn  and  the 
main  cell  assumes  a  globular  form;  it  then  elongates  and  a  constriction 
occurs  at  right  angles  to  the  long  axis.  The  nucleus  divides  by  karyo- 
kinesis  and  in  the  course  of  a  few  minutes  the  halves  of  the  nuclear 
plate  separate  and  retreat  to  the  opposite  ends  of  the  constricted  cell 
which  now  divides  into  two,  each  new  cell  acquiring  a  flagellum. 
Sometimes  the  swarm  cells  become  encysted  to  form  the  so-called 
microcysts,  or  zoocysts. 

The  spores  of  Ceratiomyxa,  which  are  borne  on  the  outside  of 
column-like  sporophores,  are  white  in  color.  The  surface  of  the 
sporophore  is  divided  into  lozenge-shaped  areas  each  with  a  projecting 
stalk  bearing  a  single  spore.  The  nucleus. of  these  spores,  according 
to  Jahn,  twice  divide  by  karyokinesis,  and  finally,  when  the  spore 
germinates,  eight  amoeboid  bodies  are  liberated,  each  of  which  develops 
a  flagellum  and  the  cluster  swims  away  by  the  lashing  of  the  flagella. 
Finally,  these  cells  separate.  All  other  myxomycetes  have  spores 
which  in  germination  produce  only  one  myxamoeba. 

Spores  of  Reticularia  which  had  been  dry  for  eight  months  germi- 
nated in  thirty-five  minutes  at  a  temperature  of  21°.  Spores  exposed 
to  a  temperature  of  37°  for  only  five  minutes  germinated  in  eleven 
minutes.  The  spores  of  Stemonitis  flaccida  germinated  in  one  hour, 
those  of  AmauroclKBte  in  two  and  one-half  hours,  those  of  Didymium  in 
four  to  five  hours,  while  it  took  the  spores  of  Stemonitis  ferruginea  in 
wood  decoction  three  to  five  days  to  germinate. 

Some  remarkable  discoveries  have  been  made  with  regard  to  an 
alternation  of  generations  in  the  slime  moulds  connected  with  a  so- 
called  sexual  act.  Jahn,  Kranzlin  and  Olive  have  worked  upon  this 
problem.  The  generation  in  all  the  Myxomycetes,  including  Ceratio- 
myxa, with  the  double  chromosome  number  (8)'  (diploid  condition)  in 
the  nuclei  is  of  short  duration.  The  nuclei  of  the  swarm  bodies,  amoe- 
boid bodies  and  the  plasmodium  have  the  single  number  (4)  of  chromo- 
somes.    Union    of    the    nuclei    to   form    fusion    nuclei    with    double 


SLIME    MOULDS    (mYXOMYCETES) 


17 


the  number  (8)  of  chromosomes  immediately  precedes  the  formation 
of  the  sporangia.  The  reduction  division,  which  results  in  the  forma- 
tion of  spores,  is  preceded  by  synapsis,  cUakinesis  and  heterotypic 
nuclear  division.  Small  nuclei  and  large  nuclei  are  seen.  The  large 
nuclei  are  probably  fusion  nuclei.  The  small  nuclei  probably 
disintegrate. 

To  the  order  Myxogastrales  belong  the  majority  of  the  Myxo- 
MYCETES  (Figs.  2  and  3).  Many  are  found  on  decaying  wood  as  Dic- 
tydium  cernumn  with  black  spore  contents,  Arcyria  nutans   and  A. 


Fig.  3. — A,  B,  Leocarpus  fragilis.  A,  Sporangium,  natural  size;  B,  capillitium 
200/1;  C.  Craterium  leucocephalum  sporangia,  6/1;  D,  Physarum  sinuosum  spor- 
angium, 6/1;  E,  F,  Tilmadoche  miitabilis;  E,  sporangia,  20/1;  F,  capillitium,  200/1. 
(.4,  C,  D,  after  nature;  B,  E,  F,  after  Rostafinski  in  Die  natiirlichen  Pflanzenfamilien 
I.  I,  p.  32.) 


punicea  have  net-like  capilHtia,  the  former  with  yellow,  the  latter 
with  a  red  one.  Lycogala  epidendrum  has  a  cinnabar-red  plasmodium 
and  a  brownish-gray  aethalium.  Trichia  varia,  T.  chrysosperma,  He- 
miarcyria  clavata  have  yellow  sporangia  and  golden-yellow  spirally 
sculptured  elaters,  Reticularia  lycoperdon  has  a  large  brown  cake-like 
aethalium.  The  yellow  plasmodium  of  Fuligo  septica  sometimes  covers 
spent  tan  bark  and  is  known  as  "flowers  of  tan. "  It  is  one  of  the  most 
generally  distributed  of  slime  moulds  and  the  writer  has  found  its 
sethaha  on  the  bark  of  street  trees  and  even  on  the  bricks  of  the  street 
pavements,  as  yellow-brown,  cake-like  fructifications  crumbling  readily 


1 8  MYCOLOGY 

into  a  powder.  The  Plasmodium  of  a  species  of  Chondriodcrma  lives  at 
the  edge  of  melting  snow  fields,  or  even  on  the  snow  itself.  The  organ- 
ism of  malaria  frequently  called  Plasmodium  malaria;  is  not  a  slime 
mould,  but  rightly  belongs  to  the  group  of  HdmosporidicB,  a  division 
of  the  Protozoa. 

The  sHme  moulds  are  cosmopolitan.  Many  of  the  same  forms  have 
been  found  in  North  and  South  America,  the  West  Indies,  Europe, 
Cape  of  Good  Hope,  AustraHa,  New  Zealand  and  Japan.  The  writer 
has  used  a  manual  of  the  Myxomycetes  of  Buitenzorg,  Java,  in  the 
identification  of  species  found  near  Philadelphia.  About  214  species  are 
represented  in  the  British  Museum  collection. 

Laboratory  Exercise. — The  wjiter  has  found  in  his  experience  as  a 
teacher  that  time  may  be  profitably  spent  by  a  class  in  mycology  in  the 
identification  of  the  common  slime  moulds.  The  sporangia,  aethalia 
and  plasmodiocarps  of  the  different  kinds  can  be  kept  separately  in 
different  small  pasteboard  boxes  and  material  out  of  these  boxes  can 
be  distributed  to  the  members  of  the  class.  The  dried  material  is  first 
treated  with  70  per  cent,  alcohol  to  remove  the  air,  and  then  the  treated 
material  is  mounted  for  permanent  preservation  in  glycerine  jelly. 
The  absorption  of  water  by  the  glycerine  jelly  is  prevented  by  a  ring 
of  asphalt.  The  "Guide  to  the  British  Mycetozoa  exhibited  in  the 
Department  of  Botany,  British  Museum  Natural  History,"  ist 
Edition,  1895,  2d  Edition,  1905,  3d  Edition,  1909,  has  been  used  in 
classes  at  the  University  of  Pennsylvania  with  much  success.  After 
the  generic  name  has  been  determined.  Lister's  "British  Mycetozoa" 
or  MacBride's  "North  American  Slime  Moulds"  can  be  used  to  find 
the  name  of  the  species. 

BIBLIOGRAPHY 

CoNARD,  H.  S.:  Spore  Formation  in  Lycogala  exigiium  Morg.     Iowa    Acad.    Sci., 

17:  83,  1910. 
Cooke,  M.  C:  The  Myxomycetes  of  Great  Britain  Arranged   According  to    the 

Method  of  Rostafinski,  96  pp.,  24  pis.,  London,  Williams  &  Norgate,  1877. 
Cooke,  M.  C:  The  Myxomycetes  of  the  United  States  Arranged  According  to  the 

Method  of  Rostafinski.     Annals  Lyceum,  Nat.  Hist.,  New  York,  11:  378-409, 

1877. 
Cook,   O.   F.:  Methods  of   Collecting  and   Preserving    Myxomycetes.     Botanical 

Gazette,  16:  263,  1891. 
DE  Bary,  Anton:  Comparative  Morphology  and  Biology  of  the  Fungi,  Mycetozoa 

and  Bacteria.     Oxford  at  the  Clarendon  Press,  1887,  especially  pp.  420-453. 


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Harper,  R.  A.:  Cell  and  Nuclear  Division  in  Fiiligo  varians.     Botanical    Gazette, 

30:  217,  1900. 
Harper,  R.  A.:  IVogressive  Cleavage  in  Didymium.     Science,  new   ser.    27:  341, 

1908. 
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Journ.  Bot.,  i:  127-143,  March,  1914,  with  2  plates. 
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Soc,  45:  271-273,  1906. 
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III.  Kernteilung  und  Geisselbildung  bei  den  Schwarmen  von  Stemonitis  flaccida, 

22:  84-92,  1904;  IV.  Die  Keimung  der  Sporen,  23:  489-497,   1905;  V.  Listerella 

paradoxa,  24:  538-541,  1906;  VT.  Kernverschmelzungen  und  Reduktionsteilun- 

gen,  25:  23-26,  1907;  VII.  Ceratiomyxa,  26":  342-352, 1908;  VIII.  Der  Sexualakt, 

29:  231-247,  1911. 
Kranzlin,  H.:  Zur  Entwicklungsgeschicte   der  Sporangien  bei  den  Trichlen  und 

Arcyrien.     Archiv  Protistenkunde,  ix:  170-194,  1907. 
Lister,  A:  Notes  on  the  Plasmodium  of  Badhamia  utricularisand  Brefeldia  maxima. 

Annals  of  Botanj^,  2:  1-24,  1888. 
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529,  1893. 
Lister,  A.:  A  Monograph  of  the  Mycetozoa,  224  pp.,  78  pis.,  p.  894. 
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3d  Edition,  1909. 
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hitherto  described  from  North  America  including  Central  America,  pp.  xvii  + 

269:  16  pis.,  MacmiUan  Co.,  1899. 
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585-587,  1899.  ^ 

MacBride,  T.  H.:  The  Slime  Moulds.     Rhodora,  2:  75-81,  1900. 
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&  Co.,  1892. 
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Arts  and  Letters,  XV :  753-773. 

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20  MYCOLOGY 

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Gazette,  lo:  290,  188';. 
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CHAPTER  III 

THE  BACTERIA  IN  GENERAL 

CLASS  II.  SCHIZpMYCETES 

The  name  Schizomycetes  comes  from  two  Greek  roots  (ax'i-^oi, 
I  split  +  ijLVKr]s,  a  fungus)  which  combined  are  equivalent  to  the  term 
splitting  fungi,  or  fission  fungi  in  allusion  to  the  manner  in  which  the 
bacterial  cells  divide.  The  Germans  call  them  Spaltpilze,  which  is 
the  German  way  of  expressing  the  same  thing.  The  name  bacteria 
is  in  American  science  used  in  a  general  sense  to  include  all  of  the 
Schizomycetes  without  reference  in  particular  to  the  genus  Bacterium. 
In  popular  use,  such  as  newspaper  articles,  these  lowly  plants  are 
described  as  germs,  microbes,  or  microorganisms.  These  English 
synonyms  are,  however,  inexact,  having  different  shades  of  meaning 
and  are  used  in  different  ways  in  common  speech,  as  consultation  with 
any  large  dictionary  of  our  language  will  show.  There  is  no  ambiguity, 
if  we  speak  of  all  the  Schizomycetes  as  bacteria,  or  bacterial  organisms. 
These  plants  are  generally  unicellular,  or  the  single  cells  are  united 
into  a  coenobium.  These  coenobia  are  filamentous,  sheet-Uke,  or  in 
groups,  seldom  arranged  in  fructification-like  masses  of  definite  form, 
as  is  the  case  with  the  Myxobaderia.  All  cells  of  the  coenobium  are 
alike  and  only  in  the  highest  developed  forms  do  we  find  a  differentiation 
into  basal  cells  and  filament  cells.  The  heterocyst,  found  in  the  blue- 
green  algae,  is  totally  absent.  The  cells  of  bacteria  are  the  smallest 
of  plant  cells;  for  example:  Micrococcus  progrediens  has  a  diameter 
of  o.i5ju  and  Spirillum  parvum  has  a  thickness  of  o.i  to  0.3^1,  but  yet 
smaller  are  the  ultramicroscopic  organisms,  which  have  come  into 
prominence  recently  as  the  cause  of  certain  diseases.  The  smallest 
bacteria  stand  at  the  borderline  o,f  what  is  with  the  best  lenses  and 
optimum  illumination  the  practical  limit  of  microscopic  vision.  On 
the  other  hand,  with  the  application  of  the  ultraviolet  light  of  short 
wave  length  in  microphotography,  it  has  been  possible  to  obtain  an 
image  of  small  objects  whose  enlargement  has  been  4000-fold.  It 
has  been  possible  with  the  ultramicroscope  of  Siedentopf  and  Zsig- 


MYCOLOGY 


mondy  to  demonstrate  small  particles  whose  size  is  only  many  million 
times  that  of  a  miUimeter.  The  accompanying  figure  (Fig.  4)  adopted 
from  Fuhrmann'  represents  the  relative  size  of  the  spheric  bacteria 
and  the  rod-shaped  organisms,  while  the  breadth  of  the  largest  known 
bacterial  cell,  that  of  Beggiatoa  mirabilis,  which  approaches  that  of  a 
human  hair  in  thickness,  is  represented  in  the  larger  area  where  the 
width  of  the  cell  is  twice  its  length. 


4. — Diagram  representing  the  relative  sizes  of  spheric  and  rod-shaped  bacteria 
{After  Fuhrmann.) 


Diameter  in  m 

I. 

Micrococcus  progredictis 

0. 

s 

Spheric 
Bacteria 

2. 

Micrococcus  urece 

I  to 

i-S 

3- 

Sarcina  maxima 

4- 

0 

.    4- 

Thiophysa  volutans 

7  to 

Length  in  /i 

18 

Breadth  in  ^ 

5- 

Pscudomonas  indigojcra 

0.18 

0.06 

6. 

Bacillus  influenza; 

4.2 

0.4 

Methane  bacillus 

50 

0.4 

Rod-shaped 

s'. 

Urobacillus  Duclaiixii 

2  to   ID 

0 . 6  to  0. 8 

Bacteria 

9. 

Bacillus  nitri 

3  to  8 

2  to  3 

10. 

Beggiatoa  alba 

2 . 9  to  s  .  8 

2.8  to   2.Q 

. 

II. 

Chromatium  Okeni 

10  to  15 

5° 

12. 

Beggiatoa  mirabilis 

ID  to   20     ■ 

1.5  to  2.0 

The  cells  exhibit  a  definite  cell  wall  which  differs  from  that  of  the 
higher  plants  in  not  containing  cellulose.  The  chemical  character  of 
the  cell  membrane  indicates  its  close  relationship  to  the  living  proto- 
plasm of  the  cell.  Chitin  has  been  found  in  the  cell  wall  of  some 
bacteria.  Frequently  the  cell  membrane  undergoes  a  mucilaginous 
modification,  so  that  the  filamentous  forms  are  surrounded  by  a  sheath 

1  Fuhrmann,  F.:  Vorlesungen  iiber  Technische  Mykologie,  Fig.  7,  page  17. 


THE   BACTERIA    IN    GENERAL  23 

and  the  numerous  individual  forms  are  united  into  slimy,  skin-like 
or  lumpy  masses  known  as  zoogloea. 

The  interior  of  the  cell  shows  no  differentiation  into  nucleus  and 
cytoplasm,  but  the  nuclein  in  certain  forms  seems  to  be  scattered  in 
the  plasma  (Fig.  5).  Considerable  diversity  of  opinion  exists  as  to  the 
nature  of  the  cell  substance  of  bacteria.  The  uniform  staining  of  the 
cell  by  ordinary  methods  suggests  that  the  cell  substance  is  all  cyto- 
plasm without  nucleus.  An  opposite  opinion  is  that  the  cell  substance 
is  composed  almost  entirely  of  nuclear  matter  (chromatin)  with  perhaps 
a  thin  layer  of  ectoplasm.  Another  view  is  that 
of  Zettnow  (Zeitschr.  f.  Hyg.,  1899:  18),  who  regards 
the  cell  body  of  bacteria  as  composed  largely  or 
almost  wholly  of  chromatin  mingled  with  varying 
amounts  of  cytoplasm.  This,  however,  can  be  said, 
that  it  is  fairly  certain  that  bacteria  contain  both 
chromatin  and  cytoplasm  which  vary  in  amount  and 
position  in  different  cells  (Fig.  5).  The  cell  mem-  Fig.  5.— i,c/!)'o- 
brane  is  mostly  colorless;  seldom  does  it  appear  BTg^glai'oT"aibl' 
greenish  or  rose-red,  as  in  the  purple  bacteria.  Bacteria  with  a  cen- 
When  colonies  of  bacteria  are  colored,  the  coloring  ch^'romatln °g'rtTns 

matter  is  an  excretion  product.  which  are  considered 

Locomotion. — The  movement  of  many  bacteria  is  equiv^rienTof^a 
a  true  movement  from  place  to  place,  not  merely  a  nucleus.  (From 
Brownian  movement.  It  is  accomplished  in  nearly  f^l"'sfLTE7uion, 
all  cases  by  the  presence  of  cilia,  or.flagella,  which  p.  91-  After 
by  some  are  considered  to  arise  directly  from  the  ^"^^'^''^^■^ 
cell  membrane,"  by  other  investigators  to  arise  from  the  ectoplasm 
within;  its  origin  in  some  way  associated  with  a  blepharoplast.  Which- 
ever view  is  the  correct  one,  the  motile  filaments  can  in  some  large 
spirilla  be  seen  in  the  living  unstained  organism,  but  generally  it  re- 
quires special  methods  of  treatment  and  staining  to  make  them  out. 
Great  differences  exist  as  to  their  distribution.  Some  forms,  as  the 
cholera  bacillus,  have  a  single  flagellum  at  one  pole  {monotrichous) ; 
others,  as  many  spirilla,  have  a  flagellum  at  each  pole  {amphitrichous) ; 
others,  as  certain  large  spirilla,  have  a  tuft  at  one  pole  {lophotrichous) ; 
while  others  have  cilia  covering  the  whole  cell,  as  the  typhoid  organism 
{peritrichous) .  Many  organisms  are  without  cilia,  or  flagella  {atrichous) , 
and  hence  are  non-motile. 


24  MYCOLOGY 

Cell  Division  mid  Reproduction. — As  with  other  plant  cells  in  general 
it  may  be  said  that  growth  is  not  conditioned  on  cell  division.  Growth 
is  the  enlargement  of  the  cell,  not  merely  a  swollen  condition,  and  this 
increase  in  size  is  within  definite  limits  for  each  species,  which  can  be 
determined  by  statistic  study.  As  long  as  division  is  not  preceded 
by  nuclear  division,  the  term  fission  is  applicable.  Certain  students 
of  the  group  claim  that  there  is  a  division  of  the  nuclear  substance 
(Fig.  6),  and  Fuhrmaftn  actually  figures  division  of  the  nuclear  mate- 
rial in  such  forms  as  Bacillus  nitri, 
''^-      ^  Micrococcus    butyricus,    Spirillum 

i_^    /  ®  ^     W      volutans  and  the  potato  bacillus. 

^       L  ^'       Possibly    then    division    of    the 

nuclear  substance  precedes  that 
of  cell  division,  and  if  that  phenom- 
enon is  found  general,  the  term 
fission    is    no    longer    apphcable. 


^. 


-O 


Fig.  6.  Fig.   7. 

Fig.  6. — Bacterium  gammari.  a,  b,  c.  Cells  with  typical  nucleus  of  nucleoplasm, 
surrounded  by  a  nuclear  membrane  and  by  one  or  two  karyosomes  also  showing 
karyokinesis;  d,  a  filamentous  bacterium  from  intestine  of  an  annelid  worm,  Bryo- 
drilus  chlorii,  each  cell  with  a  nucleus.  {From  Marshall.  Microbiology,  Second  Edi- 
tion, p.  89,  after  Vejdowsky.) 

Fig.  7. — Cells  of  Bacillus  megatherimn.  i.  Polar  granules  as  nuclei;  2,  increase 
in  size  of  nucleus  at  time  of  sporulation;  3,  same;  4,  change  in  size  of  nucleus  which 
is  surrounded  by  a  membrane  and  becomes  a  spore.  (Fro?n  Marshall,  Microbiology, 
Second  edition,  p.  90,  after  Penan) 

Cell  division  may  take  place  quite  rapidly  under  favorable  conditions. 
Bacillus  siihtilis  divides  in  thirty  minutes;  Vibrio  cholera,  every  twenty 
minutes.  The  young  cells  attain  full  size  in  a  short  space  of  time. 
Bacteriologists  have  estimated,  that  if  bacterial  multiplication  was 
unchecked  and  the  division  of  each  cell  was  accomplished  inside  of  an 
hour  that  in  two  days  the  descendants  of  a  single  cell  would  number 
281,500,000,000,  and  that  in  three  days  the  offspring  of  a  single  cell 
would  weigh  148,356  hundredweights.  Lack  of  food,  accumulation  of 
bacterial  products  injurious  to  the  organisms  that  formed  them  explain 
why  their  rapid  multiplication  is  kept  in  check. 

fformr  library 

Ml   r    Qtnt0  Cnllpift 


THE   BACTERIA    IN    GENERAL  25 

The  spores  formed  by  the  bacteria  are  of  two  kinds,  arthrospores 
and  endospores.  Arthrospores  are  whole  vegetative  cells  which  by  a 
thickening  of  their  walls  become  resting  spores.  Some  bacteriologists 
would  not  include  arthrospores  as  true  spores.  The  true  spores  are 
formed  in  the  cells  and  differ  from  the  cells  in  resisting  greater  heat 
and  by  other  definite  structural  and  physiologic  quaUties.  (Fig.  7.) 
The  shape  of  the  cell  may  be  altered  with  the  formation  of  one  or  two 
spores  within  (endospores).  In  the  hav  bacillus,  the  spore  occupies  the 
center  of  the  cell  and  is  smaller  than  the  original  mother  cell,  hence  the 
shape  of  the  parent  cell  is  not  altered.  Bacterium  pants  and  Bacillus 
amylobacter  become  swollen  in  the  middle  when  the  spore  forms  so  that 
the  mother  cell  becomes  spindle-shaped.  The  bacillus  of  lockjaw  de- 
velops a  spore  at  one  end  of  the  cell,  which  becomes  drumstick-shaped, 
hence  the  German  name  trommelschlagel  for  such  forms  and  the  generic 
name  Plectridium  now  given  to  cells  that  produce  terminal  spores. 

Bacillus  amylobacter  may  develop  one  terminal  spore,  or  two  spores, 
one  at  each  end  of  the  cell,  so  that  the  mother  cell  becomes  dumbbell- 
shaped.     Bacillus  inflatus  may  develop  two  spores  also. 

Spores  may  germinate  at  the  poles,  as  in  Bacillus  BiitscJili  and  B. 
amylobacter ;  at  the  equator,  as  in  Bacillus  subtilis  and  B.  loxosporus,  or 
obliquely,  as  in  Bacillus  loxosus.  In  germination  resting  spores  absorb 
water,  and  become  more  or  less  swollen,  when  the  spore  membrane 
is  dissolved  and  the  germ  tube  protrudes. 

The  classification  of  bacteria  according  to  their  special  activities, 
or  the  products  formed  by  these  activities,  is  useful  in  presenting 
another  phase  of  the  subject  to  the  mycologic  student.  The  fact  is 
noteworthy  that  we  can  group  the  various  organisms  into  the  photo- 
genic (light-producing),  chromogenic  (color-producing),  thiogenic 
(sulphur-producing),  zymogenic  (ferment-producing),  pathogenic  (dis- 
ease-producing), saprogenic  (decay-producing)  and  thermogenic  (heat- 
producing)  without  reference  to  their  morphology,  or  genetic  rela- 
tionship. It  is  useful  to  be  able  to  discuss  the  light,  heat,  color,  etc., 
produced  by  these  organisms  as  distinct  phenomena  worthy  of  experi- 
mental treatment. 

Photogenic  Bacteria. — The  phosphorescence  associated  with  decaying 
haddocks,  mackerel  and  other  sea  fishes,  the  faint  glow  seen  on  badly 
preserved  meats  (beef,  mutton,  veal)  and  sausages  are  produced  by 
photogenic  bacteria.     Most  success  is  obtained  by  using  sea  fishes  in 


26  MYCOLOGY 

experimenting  with  the  phosphorescent  bacteria,  for  these  organisms 
require  in  their  culture  media  from  2  to  3  per  cent,  of  sodium  chloride, 
besides  the  usual  salts  and  peptone,  the  medium  should  contain  some 
other  source  of  carbon,  such  as  sugar,  glycerine,  etc.  The  number  of 
known  photogenic  bacteria  is  considerable.  Migula  names  twenty- 
five  species  and  Molisch  twenty-six.  A  few  need  only  be  mentioned 
here,  viz.:  Bacterium  phosphor escens  Fischer;  Bacillus  photogenus 
Molisch;  B.  luminescens  Molisch;  Microspira  glutinosa  (Fischer) 
Migula;  M.  luminosa  (Beijerinck)  Migula;  Pseudomonas  javanica 
(Eijkmann)  Migula.  The  results  of  numerous  experiments  are  that 
the  production  of  light  by  bacteria  is  an  exclusively  aerobic  phenome- 
non, for  in  the  absence  of  oxygen,  they  are  non-luminous.  The  light 
is  sometimes  strong  enough  that  jars  containing  luminous  bacteria  can 
be  photographed  by  the  light  emitted  by  the  organisms  within  the  jar. 

Chromogenic  Bacteria. — Most  bacteria  are  colorless  and  even  in  such 
forms  in  which  color  is  associated  with  their  growth  on  culture  media, 
the  organisms  are  colorless.  The  bacillus  which  causes  the  "bleeding 
host,"  Bacillus  prodigiosus,  is  colorless  with  the  pigment  in  the  form  of 
granules  scattered  about  between  the  bacterial  cells.  In  other  cases, 
the  pigments  and  fluorescent  substances  are  diffused  in  the  culture 
medium  outside  the  living  cells.  Hence,  we  may  call  such  bacteria  as 
chromoparous.  The  chromophorous  species  are  those  in  which  the 
protoplasm  is  actually  colored.  Such  are  some  sulphur  bacteria 
Chromatium  and  Thiocystis,  and  finally,  there  are  some  forms  as  Bacillus 
violaceus  in  which  pigment  is  lodged  in  the  cell  wall,  when  we  may  call 
them  parachromatophorous.  Practically  all  of  the  colors  of  the  spectrum 
are  represented  in  the  color  productions  of  bacteria:  violet  {Bacillus 
violaceus),  indigo  {B.  janthinus),  blue  {B.  pyocyaneus),  green  {B. 
fluor escens),  yellow  {Sarcina  lutea),  orange  {Sarcina  aurantiaca)  and  red 
{B.  prodigiosus).  The  erythrobacteria,  or  colored  sulphur  bacteria, 
are  unique  in  the  power  of  assimilating  carbon  dioxide  in  the  presence 
of  sunlight  by  the  activity  of  bacteriopurpurin  (a  red  coloring  matter) 
which  behaves  Hke  the  chlorophyll  of  green  plants. 

Thermogenic  Bacteria. — Such  substances  as  hay,  silage,  manure  and 
cotton  waste  frequently  become  heated,  the  temperature  inside  the 
mass  being  raised  to  60°  or  7o°C.  This  spontaneous  heating  is  due  to 
the  respiratory  activity  of  the  thermogenic  bacteria  of  Cohn  (aerobic), 
which  set  up  fermentation  and  putrefaction.     The  horticulturist  uses 


THE    BACTERIA    IN    GENERAL  27 

manure,  especially  horse  manure,  in  the  construction  of  hot  l)eds  for 
the  cultivation  and  forcing  of  young  plants.  In  silos,  the  highest 
temperature  recorded  during  the  fermentation  of  the  ensiled  material 
was  7o°C.  but  the  best  silage  is  secured  by  keeping  the  temperature 
below  5o°C.  Sometimes  this  spontaneous  heating  increases  to  the  point 
of  actual  ignition  (spontaneous  combustion)  and  it  may  occasionally 
happen  that  such  substances,  as  baled  cotton,  may  be  set  on  fire  in  this 
way,  for  Cohn  found  in  damp  cotton  waste  a  Micrococcus  which,  when 
furnished  with  a  plentiful  supply  of  air,  raised  the  temperature  of  the 
decaying  mass  to  67°C. 

Aerobic  and  Anaerobic  Organisms. — Another  useful  division  of 
bacteria  is  into  those  which  are  aerobic,  requiring  oxygen  for  their 
growth,  and  anaerobic,  those  which  are  indifferent  to  the  presence  of 
oxygen.  The  process  of  respiration  in  the  aerobes  is  the  same  as  in 
all  ordinary  organisms.  Contrasted  with  the  obligatory  aerobes,  we 
have  those  which  thrive  only  in  the  absence  of  oxygen  (obligatory 
anaerobes).  The  growth  of  some  of  the  latter  is  inhibited  by  small 
traces  of  oxygen  (Bacillus  tetani  and  some  butyric  organisms).  One 
of  the  classic  experiments  in  biology  was  devised  by  Engelmann 
(Botanische  Zeitung,  1881  and  1882)  to  detect  minute  traces  of  free 
oxygen.  It  is  a  well-known  fact  that  in  the  process  of  photosynthesis, 
or  carbon  fixation,  by  green  plants  that  free  oxygen  is  formed.  Experi- 
ments have  shown  that  not  all  the  rays  of  the  spectrum  are  equally 
effective  in  causing  this  chemic  change.  The  red  rays  between  Fraun- 
hofer's  lines  B  and  C  are  most  effective  and  after  them  those  just 
beyond  the  F  line.  It  is  these  rays  that  are  most  active  in  the  evolution 
of  oxygen.  Engelmann  reasoned,  that  if  a  green  alga  was  placed  under 
the  microscope  and  illuminated  from  below  by  a  spectrum,  so  that  the 
algal  filament  paralleled  the  band  of  spectrum  colors,  that  if  aerobic 
organisms  were  introduced  into  water  beneath  the  cover  glass,  these 
aerobic  organisms  would  congregate  in  greatest  numbers  along  the 
green  alga  at  those  points  illuminated  by  the  rays  most  effective  in 
oxygen  evolution  by  the  plant.  His  anticipations  were  realized  for 
he  found  a  grouping  of  the  aerobic  bacteria  in  the  neighborhood  of  the 
B  and  C  Fraunhofer  lines  and  beyond  the  F  line,  where  theory  told  him 
to  expect  the  greatest  photosynthetic  activity.  Such  minute  quan- 
tities of  oxygen  must  be  formed  by  a  filamentous  green  alga,  that  this 
experiment  becomes  a  microchemic  test  for  the  gas. 


CHAPTER  IV 
CLASSIFICATION  OF  BACTERIA 

Classification  According  to  Nutrition. — An  illuminating  classification 
of  bacteria  has  been  based  on  their  mode  of  life,  where  three  biologic 
groups  may  be  recognized:  the  prototrophic,  the  metatrophic  and  the 
paratrophic  bacteria.  The  prototrophic  bacteria,  which  include  the 
nitrifying  bacteria,  bacteria  of  root  nodules,  sulphur  and  iron  bacteria 
and  erythrobacteria,  are  those  which  either  require  no  organic  com- 
pounds for  their  nutrition,  or  which  given  a  small  amount  of  organic 
carbon  can  derive  all  of  their  nitrogen  from  the  atmosphere,  or  which 
with  a  minimum  of  organic  matter  can  derive  energy  by  breaking  up 
inorganic  bodies. 

The  sulphur  bacteria  live  in  sulphur  springs  where  hydrogen  sul- 
phide (HoS)  is  formed  by  putrefaction  of  dead  animals  and  plants. 
The  sulphur  bacteria  in  such  places  form  a  white  furry  growth  on  the 
rotting  vegetation.  Here  the  H2S  is  attacked  and  water  and  sulphur 
are  formed,  H2S  +  O  =  H2O  -\-  S.  The  sulphur  is  deposited  in  the 
living  cells  of  the  bacteria  as  yellow  amorphous  granules,  which  impart 
to  the  organism  a  yellow  color.  To  explain  the  facts  observed,  we  need 
assume  only  that  the  protoplasm  increases  the  oxidizing  power  of  the 
atmospheric  oxygen  and  renders  it  active.  The  conversion  of  H2S 
into  water  and  S  gives  71  calories  and  the  further  oxidation  of  the  freed 
sulphur  into  sulphuric  acid  2109  calories.  The  fact  that  the  sulphur 
bacteria  can  live  without  organic  compounds  together  with  their  inability 
to  live  without  sulphur  indicates  that  it  is  the  oxidation  of  the  sulphur 
alone  which  takes  the  place  of  respiration  in  other  organisms. 

The  ferrobacteria  live  in  stagnant  pools  in  marshy  places.  On 
such  pools  of  water,  we  find  a  greasy  scum  of  ferric  hydroxide  Fe(0H)3 
together  with  organic  matter  and  some  phosphate  of  iron.  The  ferric 
compounds  are  reduced  by  the  action  of  reducing  substances  formed  by 
putrefaction  to  the  ferrous  state  which  are  dissolved  by  carbon  dioxide 
CO2  and  unite  also  with  it  to  form  ferrous  carbonate.  The  atmospheric 
oxygen  can  convert  this  carbonate  back  to  ferric  hydroxide,  but  Wino- 


CLASSIFICATION    OF   BACTERIA  29 

gradsky  has  shown  that  the  process  is  assisted  by  the  iron  bacteria 
and  the  ferric  hydroxide  is  deposited  as  a  tube  about  such  organisms 
as  Leptothrix  ochracea.  These  tubes,  or  sheaths,  are  deposited  later 
as  bog  iron  ore. 

The  nitrifying  bacteria  are  found  in  the  soils  of  our  gardens,  fields 
and  meadows  and  in  virgin  soil  derived  from  places  the  world  over. 
Winogradsky  has  discovered  that  the  conversion  of  ammonia  into 
nitric  acid  takes  place  in  two  steps  and  that  bacteria  are  effective  in 
both  of  these  operations.  One  set  of  bacteria  belonging  to  the  genera 
Nitrosococcus  and  Nitrosomonas  oxidize  the 
ammonia  to  nitrous  acid,  or  its  nitrite,  and  the 
conversion  of  this  nitrous  acid  (nitrite)  to  nitric 
acid,  or  its  nitrate,  is  accomplished  by  Nitro- 
bader.  Nitrosococcus  is  a  non-motile  spheric 
cell,  3^t  in  diameter,  found  in  soil  from  South 
America  and  Australia,  while  Nitrosomonas 
europcea  found  in  all  soils  from  Europe,  Africa 
and  Japan  is  a  short  ellipsoidal  motile  iorm  0.9 
to  iju  wide  and  1.2  to  i.8/x  long  with  a  short 
cilium.  Nitrosomonas  javanensis  from  Java  is 
almost  spheric,  0.5  to  0.6/^,  with  a  cilium  30/x 
long,  which  is  the  longest  known  among  bac- 
teria.    Nitrobacter  are  minute  non-motile  rods 

/  .  ,  \        rr.1  •  r   ii.  Fig.   8. — Roots    of  soy 

(o.5M  X  0.25M).  These  organisms  are  of  the  i,ean.  Glycine  his pida,  with 
greatest  importance  in  putting  the  nitrogen  of  tubercles.      (After    Conn, 

,1  •!•-  r  !•!  uuuji         Agricultural      Bacteriology, 

the  sou  mto  a  form  which  can  be  absorbed  by   p  g^  ) 
the  roots  of  the  cultivated  plants. 

The  bacteria  which  produce  the  nodules  (Fig.  8)  on  the  roots  of 
leguminous  plants  are  probably  the  same  the  world  over  and  to  them 
Beyerinck  has  given  the  name  of  Bacillus  radicicola,  while  Frank  called 
them  Rhizobium  leguminosarum  (Fig.  10).  When  the  seeds  of  clover,  or 
some  other  leguminous  species  are  planted,  and  soon  after  the  primary 
root  appears  with  its  root  hairs.  Bacillus  radicicola,  attracted  chemo- 
tactically  to  the  fine  root  hairs,  penetrates  the  walls  of  these  root  hairs 
by  ferment  action.  So  many  bacilli  enter  the  root  hair  cells  that  they 
form  slimy  cords,  almost  hyphae-like,  as  they  move  into  the  middle 
cortex  cells  of  the  root.  Here  in  the  cortex  cells,  the  microorganisms 
form  nests  or  pockets,  that  are  filled  with  the  nodule-producing  bacteria 


30 


MYCOLOGY 


(Fig.  9).  The  presence  of  these  bacteria  causes  the  formation  of  swell- 
ings, tubercles,  or  nodules  on  the  roots  of  the  leguminous  plants.  Here 
Bacillus  radicicola  remains,  utilizing  free  atmospheric  nitrogen  until 
about  the  time  of  flowering  of  the  host,  when  it  begins  to  assume  in- 
volution forms,  enlarging  considerably  and  assuming  S-shaped  or 
Y-shaped  forms    (Fig.  i  o) .     Then  they  are  gradually  absorbed  by  the 


""*>§»**' 


Fig.  9. — Cells  of  root  tubercle  of  Lupinus  angustifolius  magnified  to  show  the 
bacteria;  four  cells  with  nuclei.  {After  Moore,  Geo.  T.,  Yearbook  U.  S.  Dept.  Agric, 
1902, 'pi.  xxxix.) 


green  leguminous  plants  and  their  substance  is  transformed  into  a 
form  of  nitrogenous  substance,  which  is  utilized  by  the  leguminous 
host,  either  as  food,  or  stored  as  nitrogenous  reserve  supplies.  The 
nodule  becomes  emptied  of  its  contents  and  remains  as  a  hollow  sac, 
enough  of  the  organisms  being  returned  to  the  soil  to  seed  it  and  provide 
for  infection  of  other  leguminous  crops  that  may  follow.     The  growth 


CLASSIFICATION    OF   BACTERIA  3 1 

of  these  useful  organisms  in  the  soil  is  stimulated  by  aeration,  by  some 
organic  material,  by  proper  soil  drainage,  by  the  application  of  lime 
which  overcomes  soil  acidity.  The  farmer  becomes  independent  of 
the  ordinary  nitrogenous  fertilizers,  which  are  expensive,  by  plowing 
under  the  leguminous  crops,  which  on  decay  yield  up  to  the  soil  the 
nitrogenous  substance  largely  accumulated  by  bacterial  action  where 
it  is  available  to  that  large  class  of  nitrogen-consuming  plants  such  as 
the  grasses,  weeds,  root  crops,  fruit  crops  and  the  like,  which  are  de- 
pendent on  the  soil  nitrates  for  their  nitrogen.  The  leguminous  plants 
as  nitrogen-storing  plants  should,  in  an  up-to-date  rotation,  be 
alternated  with  the  nitrogen-consuming  crops. 


C'  '"b-^y 


Fig.  io. — Left,  branching  forms  of  bacteria  from  clover  tubercle  (X2000); 
right,  rod  forms  from  fenugreek  tubercle  (  X 2000).  {After  Moore,  Geo.  T.,  Yearbook 
U.  S.  Dept.  Agric,  1902,  pi.  xxxix.) 

Metatrophic  Bacteria. — The  metatrophic  bacteria  include  the  zymo- 
genic, saprogenic  and  saprophile  bacteria,  which  cannot  live  unless 
they  have  organic  substances  at  their  disposal,  both  nitrogenous  and 
carbonaceous.  They  flourish  where  organic  substances  and  foodstuffs 
are  exposed  to  decay  in  impure  water  and  in  the  waste  from  animal 
bodies.  Many  of  them  produce  profound  fermentative  changes 
(zymogenic  bacteria)  in  bodies.  Others  cause  putrefaction  and  decay 
(saprogenic  bacteria),  while  others  develop  in  media  which  have  been 
decomposed  by  saprogenic  species  and  as  saprophile  organisms  break 
these  substances  up  into  simpler  chemical  form. 


32  MYCOLOGY 

P'ermentation  is  well  exemplified  in  an  old  and  well-known  process, 
the  conversion  of  alcohol  into  acetic  acid  by  a  number  of  organisms 
morphologically  very  similar.  Hansen  considers  that  there  are  three 
different  species  concerned  in  the  acetic  fermentation,  namely,  Bacterium 
aceticum,  B.  Pasteurianus  and  B.  KiUzingianus,  which  are  non-motile, 
medium-sized  rods  often  in  chains  and  forming  pellicles  which  appear 
on  the  surface  of  the  liquid,  afterward  sinking  to  form  in  the  liquid  a 
deposit  known  as  mother  of  vinegar.  The  changes  which  take  place 
in  the  conversion  of  alcohol  to  acetic  acid  may  be  expressed  as  follows: 

CH3.CH2.OH  +  O  =  CH3.CHO  -f  H2O 

Alcohol  Aldehyde 

CH3.CHO  +  O  =  CH3.COOH 

[Aldehyde  Acetic  Acid 

This  is  conducted  in  barrels  with  wood  shavings,  where  the  alcoholic 
fluid  trickling  over  the  shavings  coated  with  the  bacteria,  and  in  contact 
with  the  air,  is  changed  to  acetic  acid. 

Lactic  acid  fermentation  is  important  to  man,  because  upon  the 
changes  in  milk  by  the  lactic  acid  organisms  depends  the  manufacture 
of  a  considerable  number  of  valuable  products  of  the  dairy,  such  as 
buttermilk  and  cheese.  This  fermentation  is  an  aerobic  process  whose 
optimum  is  found  between  30°  and  3S°C.  There  is  a  considerable 
number  of  bacteria  capable  of  converting  milk  sugar  into  lactic  acid, 
such  as  Vibrio  cholera,  Bacillus  prodigiosus  and  others,  but  the  true  lactic 
acid  bacteria  are  those  which  are  the  cause  of  the  souring  of  milk. 
Formerly,  they  were  all  classed  as  Bacterium  acidi  lactici,  but  recent 
investigations  have  shown  that  not  one  species  but  a  considerable 
number  are  at  work,  sometimes  one  form;  sometimes  another  being 
active.  A  common  kind  is  a  short  non-motile  rod,  o.^^xX.  i  to  2/^, 
facultatively  anaerobic,  known  by  such  names  as  Bacterium  acidi  lactici, 
B.  aerogenes,  and  probably  comprising  several  races  of  one  species. 
The  true  lactic  acid  fermentation  is  the  change  of  lactose,  or  milk 
sugar,  into  lactic  acid.  As  lactose  is  not  directly  fermentable  it  must 
"be  converted  into  such  simple  sugars  as  glucose  and  galactose.  The 
following  equation  approximately  represents  the  chemic  change 
involved. 

C12H02O11  +  H2O  =    CeHi.Ofi  -f  CeHisOe 

Lactose  Water  Glucose  Galactose 

C6Hi20r.    =      2C3Hfi03 

Lactic  Acid 


CLASSIFICATION    (W   BACTERIA  ^t^ 

Several  other  important  fermentations  are  due  to  bacteria,  as  the 
causal  organisms,  namely,  the  butyric,  cellulose,  and  mucilaginous 
fermentations.  The  retting  of  vegetable  fibers,  the  manufacture  of 
indigo,  the  curing  of  tobacco  are  all  dependent  on  bacterial  fermentations. 

The  saprogenic  organisms  are  concerned  with  decay,  or  putrefac- 
tion. The  decomposition  of  dead  animal  and  plant  bodies  is  far  from 
being  a  simple  putrefactive  process.  Nitrogenous  and  non-nitrogenous 
bodies  are  both  concerned  in  the  putrefactive  changes  and  they  are 
broken  down  into  simpler  nitrogenous  and  non-nitrogenous  compounds, 
or  even  elements.  Proteins  are  spUt  up  into  albumoses  and  peptones, 
aromatic  compounds  (indol  and-  skatol),  amino  compounds  (leucin, 
tyrosin,  glycocol),  fatty  and  aromatic  acids  and  inorganic  end  products 
(nitrogen,  ammonia,  hydrogen,  methane,  carbon  dioxide  and  hydrogen 
sulphide).  Ptomaines  and, 'other  poisonous  bodies  are  formed  known 
as  toxins,  a  name  applied  indiscriminately  to  all  bacterial  poisons.^ 

The  activity  of  all  these  organisms  in  causing  decomposition  of 
animal  and  plant  products  is  important  in  preserving  the  circulation 
of  carbon  and  nitrogen  in  nature.  Without  such  destructive  changes, 
the  elements  carbon  and  nitrogen  would  be  combined  in  such  a  form 
as  to  be  forever  lost  to  animals,  and  plants.  In  the  dissolution  of  these 
complex  bodies,  the  simpler  chemic  compounds  are  released  and  can 
be  used  over  again  by  living  animals  and  plants.  Much  should  be 
made  of  the  circulation  of  the  elements  in  nature  and  the  two  chief 
cycles  are  the  carbon  cycle  and  the  nitrogen  cycle  with  a  sulphur  and 
phosphorus  cycle  as  well.  There  are  two  main  processes  in  organic 
life:  the  constructive  processes  (anabolism),  and  the  destructive 
processes  (katabolism) .  Construction  is  accomplished  mainly  by  green 
plants  and  the  prototrophic  bacteria.  Destruction  is  the  work  of 
animals,  metatrophic  and  paratrophic  organisms;  which  have  to  break 
down  organic  matter  to  Uve.  Thus  the  elements  of  the  organic  world 
are  kept  in  perpetual  circulation. 

Paratrophic  Bacteria. — -These  organisms  occur  only  in  the  tissues 
and  vessels  of  living  organisms  and  are,  therefore,  true  parasites.  Many 
of  them  are  responsible  for  animal  and  plant  diseases  and  the  special 
types,  as  far,  as  they  concern  this  book,  namely,  those  which  induce 

^Consult  Lathrop,  Elbert  C:  The  Organic  Nitrogen  Compounds  of  Soils  and 
Fertilizers.  Journ.  Franklin  Inst.  1S3  :  169-206,  Feb.;  303-321,  Mch.;  465- 
498,  Apr.,  191 7. 


34  MYCOLOGY 

diseases  in  plants  will  be  considered  at  length  in  another  section. 
Most  attention  has  been  paid  to  diseases  of  animals  and  man  due  to 
bacteria  and  the  number  of  special  works  dealing  with  the  subjects  of 
bacteriology,  pathology,  immunity  and  disease  would  form  a  library. 
Nearly  every  phase  of  the  relationship  of  bacteria  to  animals  and  man 
has  been  cultivated,  and  microbiology  has  been  placed  on  a  firm  founda- 
tion, as  a  subject  of  human  inquiry.  The  field  is  too  vast  for  one  man 
to  cultivate  it,  and  hence,  we  find  a  narrow  specialism  perhaps  more 
than  in  any  of  the  other  departments  of  biologic  investigation. 

An  interesting  phase  of  the  relationship  of  parasite  and  host  has 
come  recently  into  the  scientific  limelight.  Dr.  Erwin  F.  Smith  in 
the  study  of  the  organism  which  produces  the  crown  gall  of  woody 
plants,  Pseudomonas  tumefaciens  (Fig.  143),  finds  that  the  growth  and 
formation  of  the  tumors  suggests  the  development  of  cancer  in  man. 
He  thinks  the  formation  of  tumors  in  plants  away  from  the  point  of 
infection  suggests  a  similarity  (Fig.  158). 

SYSTEMATIC  ACCOUNT  OF  THE  BACTERIA 

For  the  use  of  students  who  may  not  have  access  to  larger  works 
on  bacteria  and  who  would  like  a  short  systematic  account  of  the 
bacteria  the  following  synopsis  is  given. 

ORDER  I.  EUBACTERIALES.— The  organisms  of  this  order 
are  unicellular,  or  in  plate-like,  spheric,  or  filamentous  coenobia,  if 
imbedded  in  a  slimy  matrix,  then  not  of  a  definite  form. 

Family  i.  Coccace^. — Single  spheric  cells.  Division  in  one, 
two  or  three  directions. 

Streptococcus.- — Division  always  in  one  direction,  coenobia,  there- 
fore, chain-like,  cells  without  flagella.  Pathogenic:  6'.  erysipelatos, 
specific  germ  of  erysipelas  to  be  distinguished  with  difficulty  from  S. 
pyogenes.  Not  pathogenic:  S.  mesenterioides  {Leuconostoc  mesen- 
terioides),  occurring  in  mucilaginous  masses  in  the  molasses  waste  of 
sugar  factories,  and  its  presence  disastrous  to  the  industry. 

Micrococcus. — Division  in  two  directions,  coenobia,  sheet-like, 
without  flagella.  Pathogenic:  Micrococcus  pyogenes  aureus  (  = 
Staphylococcus  pyogenes  aureus),  the  cause  of  pus  formation  and 
purulent  discharge  from  wounds,  M.  gonorrhxce  (=  Gonococcus  gonor- 
rhcece)  specific  germ  of  gonorrhoea.  Not  pathogenic:  M.  aurantiacus, 
luteus,  cinnabareus  producing  pigments. 


CLASSIFICATION    OF   BACTERIA  35 

Sarcina. — Division  in  three  planes,  coenobia  in  bales,  or  pockets, 
no  flagella.  S.  ventriculi,  frequent  in  the  stomach  of  men,  but  non- 
pathogenic. S.  aiirantiaca,  flava,  luiea  are  chromogenic.  .S'.  rosea 
with  red  cell  contents  occurs  in  swamps,  or  colors  the  soil  a  rose-red 
color. 

Planococcus. — Division  and  coenobic  formation  as  in  Micrococcus, 
flagellate.     P.  citreus  produces  a  yellow  color. 

Planosarcina. — Division  and  coenobic  formation  as  in  Sarcina, 
flagellate. 

Family  2.  Bacteriace.e. — Cells  longer  or  shorter  cylindric, 
straight,  or  at  least  never  spirally  twisted.  Division  always  at  right 
angles  to  the  long  axis,  and  only  after  a  preliminary  elongation  of  the 
cell.  The  rods  may  separate  early  in  some  species,  in  others  they 
remain  united  for  a  considerable  time  as  longer  or  shorter  filaments. 
Endospores  are  frequent,  rare,  or  wanting.  Flagella  may  or  may  not 
be  present. 

Bacterium  (Ehrenberg  char,  emend.). — Cells  as  longer  or  shorter 
cylindric  rods,  often  forming  filaments  of  considerable  length.  With- 
out flagella.  Endospore  formation  in  many  species,  absent  in  others. 
Erwin  F.  Smith  ("Bacteria  in  Relation  to  Plant  Diseases":  168  to 
171)  believes  that  bacteriologists  should  substitute  Bacterium  for 
Pseudomonas  as  the  older  generic  name,  and  he  would  establish  a  new 
generic  name  Aplanobacter  for  the  non-motile  forms  generally  referred 
to  Bacterium.  This  distinction  is  not  adopted  in  this  text-book. 
Pathogenic:  Bacterium  (Aplanobacter)  Rathayi  the  cause  of  Rathay's 
disease  of  the  orchard  grass;  B.  michiganense  the  cause  of  the  Grand 
Rapids  (Mich.)  tomato  disease;  B.  anthracis  the  first  organism  deter- 
mined to  be  the  cause  of  disease,  causing  anthrax  or  splenic  fever; 
B.  mallei  specific  in  glanders  in  men  and  horses; 5.  pneumonice,  the  cause 
of  pneumonia;  B.  tuberculosis  responsible  for  tuberculosis  (consumption, 
phthisis)  in  man  and  animals.  It  can  be  distinguished  by  its  staining 
reactions.  If  stained  with  carbol  fuchsin  and  then  treated  with  dilute 
nitric  acid  (1:5),  the  stain  remains  fast,  while  with  other  organisms, 
the  stain  will  be  washed  out.  After  this  treatment  the  tissues  can  be 
treated  with  methylene  blue  for  differential  staining.  B.  leprcB,  the 
organism  of  leprosy;  B.  influenza,  the  cause  of  influenza,  or  grippe;  B. 
diptheritidis,  the  causal  bacterium  of  diphtheria;  B.  pestis,  specific  in 
the  disease  known  as  the  plague,  which  as  the  Black  Death  devastated 


36  MYCOLOGY 

London  in  1665  in  which  70,000  persons  perished.  It  is  carried  by 
infested  rats. 

N on- pathogenic:  B.  acelicum  sets  up  in  alcohoHc  sokition  the  acetic 
acid  fermentation  and  its  films  later  form  mother  of  vinegar.  B. 
acidi  lactici  ferments  sweet  milk  transforming  it  into  sour  milk  where 
the  acidity  is  due  to  lactic  acid.  B.  phosphoreiim  is  a  phosphorescent 
fresh- water  organism. 

Bacillus  (Cohn  char,  emend.). — Cells  straight,  rod-shaped  to  ovoid, 
long  or  short,  sometimes  united  into  filaments.  Motile  by  wavy, 
bent  flagella  scattered  over  the  whole  surface  of  the  cell.  Formation 
of  endospores  frequent.  Motility  may  be  active  for  a  time,  and  then 
is  lost.  Pathogenic:  B.  muscB  causes  the  Trinidad  banana  disease; 
B.  tracheiphilus  is  responsible  for  the  wilt  of  cucurbitaceous  plants; 
B.  amylovorus,  the  pear-blight  organism;  B.  carotovorus,  specific  in 
soft  rot  of  carrot;  B.  aroidew,  an  organism  which  causes  soft  rot  of  the 
calla;  B.  tetani,  the  causal  microbe  in  tetanus,  or  lockjaw,  is  found  in 
the  soil  and  may  enter  the  skin  or  superficial  muscles  of  man  through  a 
pin  prick,  or  rusty  nail  point;  B.  typhi,  the  typhoid  bacillus.  Non- 
pathogenic: Bacillus  subtilis,  the  hay  bacillus  found  in  hay  infusion,  and 
is  the  cause  of  decay.  B.  coli  in  the  alimentary  canal  of  animals  and 
men  and  in  the  water  polluted  by  sewage.  B.  butyricus  produces 
butyric  acid  fermentation  and  the  coagulation  of  casein.  B.  radicicola 
(=  Rhizobium  leguminosarum)  lives  in  the  roots  of  leguminous  plants 
and  forms  the  root  tubercles  or  nodules  (Figs.  8,  9,  10).  B.  amylobacter 
(=  Clostridium  butyricum)  ferments  cellulose,  dissolves  casein  and  is 
useful  in  the  retting  of  plants  for  fiber  production.  B.  prodigiosus 
is  found  on  many  food  substances  imparting  to  them  a  dark  red  color. 
B.  calfactor  appears  in  hay  infusions,  where  it  produces  a  rise  of  tem- 
perature. B.  putrificus,  a  widely  distributed  organism.  Many  bacilli 
that  occur  in  the  ocean  are  luminous. 

Pseudomonas. — Cylindric  bacteria,  sometimes  long,  sometimes  short, 
occasionally  in  threads.  Locomotion  accomplished  by  polar  flagella, 
the  number  of  which  may  vary  from  one  to  ten,  most  frequently 
one  flagellum  is  present,  or  three  to  six.  Endospores  are  formed,  but 
are  rare.  The  following  are  the  causes  of  diseases  in  cultivated  plants: 
Pseudomonas  campestris  is  responsible  for  the  black  rot  of  cabbage  and 
other  cruciferous  plants.  Ps.  hyacinthi  causes  the  yellow  disease  of 
hyacinths.     Ps.  vascularum  is  associated  as  the  causal  bacterium  in 


CLASSIFICATION    OF  BACTERIA  37 

Cobb's  disease  of  sugar  cane.  Ps.  pyocyanea  causes  blue  pus.  Ps. 
putida  occurs  in  water,  where  it  develops  a  green  fluorescent  pigment. 
Ps.  syncyanea  produces  in  milk  a  blue  coloring  matter  (blue  milk). 
Ps.  etiropcea  belongs  to  the  group  of  organisms  which  cause  nitrification. 

Family  3.  Spirillace^.^ — Spirally  wound  or  bent  cells  with  occa- 
sional endospore  formation,  usually  motile.  Cell  division  transverse 
to  the  long  axis  of  the  cell. 

Spirosoma. — -Spirally  bent,  rigid  cells  usually  rather  large  and  with- 
out flagella.  Unicellular  free  or  enveloped  in  a  gelatinous  capsule. 
Only  a  few  species  are  known. 

Microspira. — -Comma-shaped,  or  sausage-shaped,  single,  or  united 
cells,  motile  by  means  of  a  single,  wavy,  polar  flagellum  (rarely  two  or 
three  flagella),  rarely  longer  tha*n  the  cell.  Endospores  unknown. 
Usually  united  with  the  next  genus. 

Spirillum. — Rigid  rod-shaped  cells  of  varying  thicknesses,  lengths 
and  pitch  of  spiral  turns,  hence,  either  as  long  screws,  or  loosely  wound. 
Flagella  occur  at  one  or  both  ends  of  the  cells  as  polar  tufts  varying  in 
number  from  five  to  twenty.  In  some  species,  endospore  formation 
has  been  observed.  Sp.  comma  is  the  cause  of  asiatic  cholera  and  is 
found  in  cultures  often  in  long  spirally  wound  filaments.  There  are 
nmny  non-pathogenic  spirilla  in  water  from  rivers  and  ponds  as  S. 
danubicum  in  the  Danube,  Sp.  berolinense  in  Spree  water,  Sp.  ruftim 
in  stagnant  water.  Sp.  rufum  forms  blood-red  slimy  masses  between 
decaying  algae. 

SpirochcBta. — Thin,  flexible,  snake-like,  motile  cells  usually  quite 
long  without  observed  flagella  and  endospores,  and  unsegmented. 
Spirochceta  Obermeieri  is  the  cause  of  relapsing  fever  (f ebris  recurrans) . 
S.  {Treponema)  pallida  is  the  organism  of  syphilis.  S.  dentium  is  found 
associated  with  the  teeth  in  man. 

Family  4.  Phycobacteriace^  (Chlamydobacteriace^). — Cylin- 
dric  cells  united  into  sheath-surrounded  threads  and  reproducing  by 
motile  or  non-motile  conidia,  which  arise  from  the  vegetative  cells 
without  a  resting  stage. 

Streptothrix  (==  Chlamydothrix,  Leptothrix,  Gallionella). — Non-motile 
cylindric  cells  in  unbranched  threads  possessing  a  sheath  of  varying 
thickness.  Septa  vague.  Reproduction  is  accomplished  by  roundish, 
non-motile  conidia  arising  from  the  vegetative  cells.  S.  fluitans  in 
water. 


38  MYCOLOGY 

Crenothrix. — The  cells  are  arranged  in  unbranched  threads  attached 
at  one  end  and  enlarging  toward  the  distal  extremity.  Filaments 
covered  by  a  rather  thick  sheath.  The  reproductive  cells  are  non- 
motile  conidia,  which  on  discharge  immediately  germinate.  Crenothrix 
polyspora  in  springs  and  water  pipes,  where  it  forms  attached  slimy 
growths.  The  sheaths  in  iron  waters  are  impregnated  with  iron 
oxidhydrate. 

Phragniidiothrix. — Cylindric  cells  with  delicate,  scarcely  visible 
sheath.  The  cells  of  the  filament  are  at  first  in  one  plane  which  later 
divide  in  three  directions  to  form  clumps  or  packets  of  cells.  Later 
the  single  cells  round  off  and  become  free.  Ph.  nrnltiseptata  with  fila- 
ments 3  to  12/X  broad  and  looyu  long  attached  to  the  bodies  of  crustaceae. 

Cladothrix  {SphceroHlus  in  part). — The  fixed  and  often  tufted 
filaments  form  delicate  sheaths.  The  cells  are  cylindric  and  by  inter- 
calary growth  may  break  laterally  through  the  sheath  to  form  false 
dichotomous  branches.  Reproduction  is  accomplished  by  motile 
swarm  spores  (gonidia)  which  bear  a  tuft  of  flagella  a  little  to  one  side 
of  a  pole.  Cladothrix  dichotoma  occurs  frequently  in  stagnant  water, 
attached  and  forming  furry  growths.  The  following  species  occur  in 
the  soil:  C.  rufula,  C.  profundus,  C.  intestinalis,  C.  fungiformis,  while 
C.  intrica  has  been  isolated  from  sea  water  and  sea  mud. 

Family  5.  Thiobacteriace^  (Beggiatoace.e). — Cells  with  sul- 
phur inclusions,  unpigmented,  or  colored  rose,  red  or  violet  by  bacterio- 
purpurin;  never  green.  The  plants  are  generally  filamentous  with 
division  transverse  to  the  long  axis. 

Thiothrix. — Unequally  thick  attached  filaments  encased  in  a 
delicate,  scarcely  visible  sheath.  Rod-shaped  conidia  are  formed  at 
the  ends  of  the  threads.  Th.  nivea  is  found  in  sulphur  springs  and  in 
stagnant  water. 

Beggiatoa. — Sheathless,  free-filamentous  bacteria,  motile  by  means 
of  an  undulating  membrane.  Cells  with  included  sulphur  granules. 
Spore  formation  unknown.  B.  alba  is  found  in  dirty  water,  drain 
water  from  sugar  factories  and  attached  to  decayed  plants  in  sulphur 
springs.     B.  mirabilis  forms  white  growths  on  dead  marine  algae. 

The  colored  sulphur  bacteria,  sometimes  placed  in  the  family 
Rhodobacteriace^,  belong  here.  They  have  rose,  red  or  violet  cell 
contents  due  to  the  presence  of  bacteriopurpurin  (see  ante).     The  im- 


CLASSIFICATION    OF    BACTERIA  39 

portaut  genera  according  to  Erwin  F.  Smith  (''Bacteria  in  Relation  to 
Plant  Diseases,"  I:  163)  are  Thiocystis,  Thiocapsa,  Thiosarcina, 
Lamprocystis,  Thiopedia,  Amosbobader,  Thiothece,  Thiodictyon,  Thiopoly- 
coccus,  as  well,  as  the  three  genera  Chromatium,  Rhabdochromatium, 
Thiospir  ilium. 

Family  6.  Actinomycetace.'E  (Position  doubtful). — Radially  ar- 
ranged branched  filaments  in  colonies,  non-motile.  Filaments  divid- 
ing into  oidia-like  reproductive  cells. 

Actinomyces  chromogenes  occurs  in  soil.  A.  bovis  is  the  cause  of 
lumpjaw  in  cattle  and  occasionally  in  man.  The  plant  occurs  in 
rosettes  usually  30  to  40/i  in  diameter.  The  filaments  which  are  often 
curved  sometimes  spirally  exhibit  true  branching  and  are  interlaced 
in  a  network.  Recently  Youngken  (Amer.  Jour.  Pharm.,  September, 
1 91 5)  has  described  the  foundation  of  the  large  swellings  (mycodomatia) 
on  the  roots  of  the  waxberry,  Myrica  carolinensis,  and  other  species,  as 
due  to  a  species  of  ray  fungus,  Actinomyces  myricarum,  that  abun- 
dantly fills  infested  cells  in  the  cortex  of  the  tubercular  swellings.  A. 
thermophilus  is  found  on  hay  and  manure. 

ORDER  II.  MYXOBACTERIALES.— Individual  plants  en- 
closed in  slimy  masses  which  assume  more  or  less  regular  fructifica- 
tion-Hke  shapes. 

Family  i.  Myxobacteriace^.^ — Erwin  Baur  and  Roland  Thaxter 
have  studied  these  forms  most  intimately.  The  plants  of  this  family 
consist  of  motile,  rod-like  microorganisms,  with  a  gelatinous  base  and 
forming  false  plasmodioid  aggregations  preceding  a  cyst-producing, 
quiescent  state  in  which  the  rods  may  be  encysted  in  groups  or  con- 
verted into  spore-masses.  The  slightly  reddish  rods  in  the  vegetative 
stage  are  elongate,  sometimes  15//  long  and  vary  httle  in  size  in  the 
different  genera  and  species.  Cell  division  is  by  fission  and  the  active 
rods  show  a  slow  sliding  movement  without  organs  of  locomotion.  The 
vegetative  phase  in  artificial  cultures  usually  lasts  about  a  week,  or 
even  two  weeks,  and  the  formation  of  cysts  which  follows  must  be  more 
rapid  in  nature.  These  organisms  are  found  in  moist  places  on  decay- 
ing wood,  dung,  funguses  and  lichens,  growing  best,  according  to  Baur, 
at  3o°C.     Three  genera  are  included  in  this  family. 

Chondromyces. — Rods  producing  free  cysts  within  which  they 
remain  unchanged.  The  cysts  are  various,  sessile  or  developed  on  a 
stalk  (cystophore). 


40 


MYCOLOGY 


Folvangiiim  {=  Myxobacter,  Cyslobacter). — The  rods  form  large 
rounded  cysts  one  or  more  of  which  are  free  inside  a  gelatinous  stalked 
matrix. 

Myxococcus. — Slender  rods  which  swarm  together,  after  a  vegetative 
phase,  to  form  well-defined,  more  or  less  sessile  or  stalked  encysted 
masses  of  coccus-like  spores. 

BIBLIOGRAPHY 

Abbott,  A.  C:  The  Principles  of  Bacteriology,  9th  Edition:  Lea  &  Febiger,  1915. 
DE  Bary,  a.:  Comparative  Morphology  and  Biology  of  the  Fungi,  Mycetozoa  and 

Bacteria.     Oxford  at  the  Clarendon  Press,  1887. 
Baur,  Erwin:  Myxobakterien  Studien.     Archiv  fur  Protistenkunde,  v  Bd.,  Heft  I, 

92-121,  1904. 
Buchanan,    Estelle    D.    and    Robert    Earle:  Household    Bacteriology.     The 

Macmillan  Co.,  New  York,  1914. 
Chester,  Frederick  D.:  A  Manual  of  Determinative  Bacteriology.     The  Mac- 
millan Co.,  1914. 
Conn,  H.  W.:  Bacteria,  Yeasts,  and  Molds  in  the  Home.     Ginn  &  Co.,  Boston,  1903. 
DuGGAR,  Benjamin  M.:  Fungous  Diseases  of  Plants.     Ginn  &  Co.,  Boston,  1909. 
Ellis,  David:  Outhnes  of  Bacteriology  (Technical  and  Agricultural),  Longmans, 

Green  &  Co.,  1909. 
Engler,  Adolf  and  Gilg,  Ernest:  Syllabus  der  Pflanzenfamilien.     Berlin,  191 2, 

Siebente  Auflage,  pp.  1-5. 
Eyre,  J.  W.  H.:  The  Elements  of  Bacteriological  Technique.     Philadelphia,  W. 

B.  Saunders  &  Co.,  1902. 
Fischer,  Alfred,  transl.  by  Jones,  A.  Coppen:  The  Structure  and  Functions  of 

Bacteria.     Oxford  at  the  Clarendon  Press,  1900. 
Fuhrmann,  Dr.  Franz:  Vorlesungen  iiber  technische  Mykologie.     Jena,  Gustav 

Fischer,  19 13. 
Hiss,  Philip  H.  and  Zinsser,  Hans:  A  Text-book  of  Bacteriology.     D.  Apple  ton 

&  Co.,  1915. 
Jordan,  Edwin  O.:  A  Text-book   of    General   Bacteriology,    3d   Edition.     Phila- 
delphia, W.  B.  Saunders  &  Co.,  191 3. 
KisSKALT,    K.:    Bakteriologie    Zweite    Auilage.     Erster   Teil    von   Prakticum   der 

Bakteriologie  und  Protozoologie.     Jena,  Gustav  Fischer,  1909. 
KtJSTER,  Dr.  Ernst:  Anleitung  zur  Kultur  der  Mikroorganismen.     Zweite  Auflage, 

Leipzig  und  Berlin,  191 3. 
Lafar,  Dr.  Franz:  Technical  Mycology.     The  Utilization  of  Microorganisms  in 

the  Arts  and  Manufactures.     London,  Charles  Griffin  &  Co.,  vol.  i,  1898. 
Lipman,  Jacob  G.:  Bacteria  in  Relation  to  Country  Life.      The  Macmillan  Co., 

New  York,  1908. 
Marshall,  Charles  E.  and  Others:  Microbiology  for  Agricultural  and  Domestic 

Science  Students.     Philadelphia,  P.  Blakiston's  Son  &  Co.,  1911. 


CLASSIFICATION    OF   BACTERIA 


41 


Meyer,  Dr.  Arthur:  Practicum  der  botanischen  Bakterienkunde.     Jena,  Gustav 

Fischer,  1903. 
MuiR,  Robert  and  Ritchie,  James:  Manual  of  Bacteriology.     The  Macmillaii 

Co.,  1913. 
Newman,  George:  Bacteria.     Especially  As  They  Are  Related  to  the  Economy 

of  Nature  to  Industrial  Processes  and  to  Public  Health.     G.  P.  Putnam's  Sons, 

New  York,  1899. 
Park,    William    H.    and    Williams,    Anna    W.:     Pathogenic    Microorganisms. 

Lea  &  Febiger,  Philadelphia,  1914. 
Perch^al,    John:  Agricultural    Bacteriology   Theoretical    and    Practical.     Duck- 
worth &  Co.,  London,  1910. 
Prescott,  Samuel  C.  and  Winslow,  Charles  Edward  A.:  Elements  of  Water 

Bacteriology,  3d  Edition.     John  Wiley  &  Sons,  New  York,  1913. 
QuEHL,   A.:  Untersuchung  liber  Myxobakterien.     Zentralblatt  fur  Bakteriologie, 

II  Abt.,  xvi  Bd.,  1906. 
Smith,  Erw7N  F.:  Bacteria  in  Relation  to  Plant  Diseases,  vol.  i,  1905;  vol.  ii,  1911; 

vol.  iii,  1914.     Publication  No.  27,  Carnegie  Institution  of  Washington. 
Th.^xter,  Roland:  On  the   Myxobacteriaceae,   a  New  Order  of  Schizomycetes. 

Bot.  Gaz.,  xvii,  1892;  Further   Observations  on  the  Myxobacteriacese.     Loc. 

cit.,  xxiii,  1897;  Notes  on  the  Myxobacteriaceae.     Loc.  cit.,  xxxvii,  1904. 
Wettstein,    Richard    R.   von:  Handbuch  der  Systematischen  Botanik  Zweite 

Auflage,  191 1 :  69-83. 


CHAPTER  V 

CHARACTERISTICS  OF  THE  TRUE  FUNGI 

CLASS  III.  EUMYCETES 

The  true  fungi  or  hyphomycetes  {v(t)ri,  a  web  +  hvktjs,  a  mushroom) 
are  thallophytes  in  which  the  thallus,  as  the  Greek  derivation  implies, 
consists  of  a  system  of  threads  {hypha)  which  form  a  cobwebby  struc- 
ture known  as  the  mycelium  (Fig.  1 1).  A  single  thread  of  the  mycelium 
is  an  hypha  (plural  hyphae)  and  a  hypha  may  be  unicellular,  or  multi- 
cellular. All  true  fungi  are  colorless,  that  is  they  are  chlorophylless; 
and  although  they  may  have  other  pigments  present,  yet  in  the  absence  of 
chlorophyll,  they  are  dependent  plants. 
As  dependent  plants,  they  must  get 
their  organic  food  from  extraneous 
sources,  and  as  all  organic  matter  is 
either  dead,  or  living,  a  natural  classi- 
fication of  fungi  into  saprophytes  and 
parasites  can  be  made.  A  saprophyte 
{aairpos,  rotten  +  4>^t6v,  a  plant)  is  any 

Fig.    II. — Gray   mould,   Miicoy,  .  i  •   i      j      •  •.         i  •   r   r      j 

showing  mycelium  and  the  sporan-  Organism  which  dcrives  its  chief  food 
gia  on  upright  sporangiophores.  supply  from  dead,  or  dead  and  decaying 
^^.^^^  ^^  plant  organic  material,  while 
a  parasite  {irapaaiTos,  one  who  lives  at  another's  expense)  is  an 
organism,  which  exists  at  the  expense  of  living  animals,  or  plants 
(Fig.  12).  But  some  saprophytes  may  change  their  mode  of  nutri- 
tion and  become  parasitic;  such  saprophytes  are  called  facultative 
parasites,  while  those  which  retain  their  saprophytism  under  all  condi- 
tions are  obligate  saprophytes.  Again  some  parasites  can  adjust  their 
methods  of  nutrition,  so  that  they  can  become  saprophytes.  Such 
parasites  are  called  facultative  saprophytes,  while  those  organisms 
which  are  always  parasitic  are  obligate  parasites.  These  distinctions 
are  useful,  but  it  should  be  emphasized  that  there  is  no  absolute  border- 
line between  one  condition  and  the  other.     There  are  imperceptible 

42 


CHARACTERISTICS    07    THE    TRUE    FUNGI 


43 


gradations  which  preclude  an  absolute  pronouncement  as  to  whether 
a  plant  is  a  saprophyte,  or  a  parasite.^  Botanists  generally  concede 
that  the  true  fungi  have  been  derived  from  filamentous  algal  ancestors 
and  the  groups  of  algae  from  which  the  principal  forms  of  fungi  have 


Fig.    12. — Russula  nigricans  parasitized  by  Nyctalis  aslerophora.      {After  Brefeld.) 


been  derived  are  fairly  well  known.  For  example,  it  is  believed  that 
such  fungi  as  belong  to  the  order  OOMYCETALES  have  been  derived 

1  Massee,  George:  On  the  Origin  of  Parasitism  in  Fungi.  Annals  of  Botany, 
xviii:  319. 

Ward,  H.  M.:  Recent  Researches  on  the  Parasitism  of  Fungi.  Annals  of  Bot- 
any, xix:  I. 

Bancroft,  C.  K.:  Researches  on  the  Life  History  of  Parasitic  Fungi.  Annals 
of  Botany,  xxiv:  359,  1910. 


44 


MYCOLOGY 


from  a  green  alga  like  Vaucheria.  With  our  present  knowledge,  it  is 
impossible  to  name  any  one  existing  alga  as  the  progenitor  of  a  definite 
fungous  form,  but  we  are  safe  in  assuming  in  a  general  way  that  certain 
phyla  of  fungi  have  been  derived  from  certain  phyla  of  algae,  by  the 
loss  of  chlorophyll  and  in  the  loss  of  an  independent  existence.  Another 
view,  which  is  open  to  argument,  is  that  certain  of  the  prototrophic 


Fig.  13. — Development  of  Mucor  miicedo.  a,  b,  c,  d,  Stages  in  the  formation  of 
zygospore;  /,  sporangium;  g,  mature  sporangiospores;  h,  one  germinating.  {After 
Schneider,  Pharmaceutical  Bacteriology,  p.  142.) 


filamentous  bacteria  to  which  attention  has  been  previously  called 
have  been  the  direct  progenitors  of  certain  of  the  filamentous  fungi, 
but  on  account  of  the  character  of  the  reproductive  organs  in  the  lower 
true  fungi  their  derivation  from  green  algae  is  the  more  probable,  and 
mycologists  even  speak  of  the  algal  fungi  referring  especially  to  aquatic 
genera,  such  as  Saprolegnia,  which  like  their  algal  ancestors  not  only 
retain  the  general  morphologic  features  of  the  algae,  but  also  live  in  an 


CHARACTERISTICS    OF   THE   TRUE   FUNGI  45 

aquatic  medium,  and  the  success  of  the  process  of  fertilization  depends 
on  the  presence  of  free  water.  Such  fungi  form  a  subclass  of  EUMY- 
CETES,  the  PHYCOMYCETES. 

The  vegetative  organs  of  fungi  are  concerned  with  the  absorption 
of  food,  the  assimilation  of  the  food  and  in  the  nutrition  of  the  organs 
of  fructification  which  together  form  the  reproductive  system.  That 
the  student  may  appreciate  the  morphology  of  the  vegetative  organs  of 
the  fungi,  three  examples  from  widely  divergent  orders  will  be  chosen 
by  way  of  illustration.  A  common  mould  is  Mucor  mucedo  which 
appears  on  horse  manure.  If  a  spore  of  this  fungus  is  placed  in  a  nutri- 
tive medium,  its  wall  breaks  and  there  protrudes  a  germ  tube  rich  in 
protoplasmic  contents  (Fig.  13,  h).  This  germ  tube  grows  in  length 
into  an  hypha  without  the  development  of  partition  walls  dividing  it 
into  shorter  cells.  This  hypha  branches  and  rebranches  in  its  growth 
over  the  nutrient  substratum  spreading  in  all  directions,  if  unimpeded 
by  other  organisms  growing  on  the  same  food  substance.  The  ultimate 
branches  of  this  mycelium,  which  is  throughout  unicellular,  are  much 
attenuated,  fine  hyphse  representing  the  end  ramifications  of  larger  and 
coarser  hyphae  nearer  the  point  of  origin  of  the  whole  mycelium  (Fig. 
13).  The  finest  hyphae  usually  enter  the  substratum,  while  the  coarser, 
stronger  hyphae  form  a  cobwebby  mass  over  its  surface.  We  can 
distinguish  therefore  the  feeding  hyphae,  which  are  rhizoidal  hyphae, 
and  the  aerial  hyphae  in  which  probably  the  metabolic  changes  are 
most  active  where  the  mycelium  is  in  open  contact  with  the  air.  Later, 
when  the  mycelium  is  well  established  on  the  nutrient  substratum, 
erect  vertical  hyphae  appear  at  indefinite  points  on  the  larger  aerial 
hyphae.  These  are  the  fruiting  hyphae,  or  sporangiophores,  which 
ultimately  cut  off  a  terminal  cell  which  becomes  the  sporangium,  or  case, 
in  which  the  reproductive  cells  or  spores  are  formed,  while  the  end  of 
the  sporangiophore  projects  into  the  interior  of  the  sporangium  as  a 
columella  (Fig.  13,  /). 

The  common  green  mould,  Penicillium  glaucum,  may  be  taken  as  the 
second  illustration  (Fig.  14).  If  we  sow  a  spore  on  nutrient  agar  in  a 
Petri  dish  after  a  few  hours  the  spore  swells  and  there  emerges  a  germ 
tube  which  at  first  is  undivided  by  a  partition  wall.  Later,  as  the  older 
hyphae  branch  to  form  new  ramifications,  cross-partitions  are  formed 
which  divide  the  mycelium  into  short  cells,  so  that  in  that  respect  the 
mycelium  of  PeniciUhim  differs  from   that   of   Mucor.     The  hyphal 


46  MYCOLOGY 

branches  are  coarser  in  Penicillium  and  do  not  form  the  fine-pointed 
ends  found  in  Mucor.  The  presence  of  transverse  walls  in  the  fungi  is 
thought  of  sufficient  importance  to  make  a  subclass  known  as  the 
MYCOMYCETES  to  contain  all  of  the  true  fungi  EUMYCETES 
which  have  a  mycelium  which  is  multicellular  in  contradistinction 
to  those  which  have  unicellular  mycelia  and  that  form  the  subclass 
PHYCOMYCETES.  From  this  spreading  myceHum  of  transversely 
septated  hyphae  in  Penicillium  arise  hyphae  which  branch  at  the 
extremity  into  a  number  of  erect  branches  from  the  ends  of  which 
are  cut  off  in  sequence  a  series  of  small  round  cells,  the  spores,  which  if 
undisturbed  remain  connected  in  a  chain,  so  that  the 
fructification  roughly  resembles  a  small  broom,  or 
whisk.  The  large  vertical  hypha  is  a  conidiophore, 
and  as  the  spores  are  pinched,  or  abstricted  off  from 
the  secondary  branches  as  single  cells,  they  are 
known  as  conidiospores  {kovls,  dust  +  airopa  a  seed) 
(Fig.  14  and  Figs.  243  to  263  inclusive). 

The  third  example,  which  we  will  use  to  describe 
in  general  terms  the  vegetative  organs  of  the  fungi, 
is  the  honey-colored  toadstool,  Armillaria  mellea 
(Fig.  15).  The  toadstools,  or  fruit  bodies,  often  form 
Fig.  14. — Con-  dense  clumps  around  the  base  of  some  dead  or  dving 
mo°n  ""Te'en-mouS;  tree,  or  almost  cover  an  old  stump  on  which  ihey 
Penicillium  glau-  grow.  The  Cap  is  of  a  houcy-colored  brown,  about 
llZnr'^oi  ^coSSo-  two  inches  across,  and  the  stem  may  be  six  inches 
spores.    (After  Conn,  long  and  paler  than  the  cap.     Microscopic  sections 

that  are  closely  bound  together  to  form  the  stem  and 
cap.  If  we  examine  the  base  of  the  stalk,  we  find  that  it  arises  from 
a  dark-colored  cord-like  strand  which  has  been  termed  a  rhizomorph 
because  of  its  resemblance  to  a  root  (Fig.  15,  II  and  IV).  These 
rhizomorphs  constitute  the  mycelium  and  they  either  ramify  through 
the  soil,  or  else  are  found  beneath  the  bark  of  the  dead  tree,  where 
they  unite  to  form  open-meshed  nets  of  a  dark  brown  color.  These 
rhizomorphs  are  strands  of  hyphae  that  run  longitudinally.  The 
hyphal  cells  are  bound  together  in  a  cord-like  cable  which  is  peculiar 
in  that  it  shows  apical  growth,  constantly  elongating  at  its  extremity, 
as   it   grows   beneath    the    bark,    or    penetrates    the    soil    (Fig.    15) 


CHARACTERISTICS    OF    THE    TRUE    FUNGI 


47 


Fig.  15. — Details  of  the  mycelium  of  Armillaria  niellea.  I,  Piece  of  mycelium 
on  slide;  II,  piece  of  old  mycelium  {Rhizomorpha  sublerranea);  III,  rhizomorph  pro- 
ducing fruit  bodies;  IV,  apex  of  rhizomorph  capable  of  growth;  (a)  peripheral  hyphs; 
{b)  pseudo-epidermis;  (c)  growing  point;  {d,  e,  h)  pith;  (/?)  hollow  center.  (7  and 
IV  after  Brefeld;  III,  after  Hartig  in  Zopf,  Die  Pilse,  1890,  p.  25.) 


48  MYCOLOGY 

its  extremity,  as  it  grows  beneath  the  bark,  or  penetrates  the  soil  (Fig. 
15).  Such  a  compound  thallus  differs  strikingly  from  the  filamentous 
thalluses  of  the  two  previously  described  fungi.  The  union  of  the 
hyphal  cells  in  some  of  these  fleshy  fungi  may  be  so  intimate  as  to  con- 
stitute a  pseudoparenchyma,  and  this  close  union  of  the  cells  may  be 
made  still  more  intimate  by  clamp  connections  where  two  adjoining  cells 
are  bound  together  endwise  by  a  clamp-like  protuberance  of  one  of  the 
cells  attached  to  the  end  of  the  other  adjoining  cell.  When  the  pseudo- 
parenchyma  is  external,  it  rnay  serve  for  the  protection  of  the  internally 
disposed  hyphae,  and  be  looked  upon  as  protective  tissue.  Mechanic 
tissues  for  the  support  of  fungi  are  not  unknown  in  some  of  the  groups, 
as  in  some  of  the  polypori;  where  there  are  clamp  connections,  trans- 
verse septa  and  thickened  cell  walls.  A  few  of  the  higher  fleshy  fungi 
have  conducting  hyphae,  which  are  larger  and  more  tubular  than  the 
surrounding  hyphae,  and  which  conduct  later,  oil  and  other  substances. 
Those  which  conduct  a  milky  juice,  as  in  some  species  of  Russula  and 
Lactarius,  may  be  termed  laticiferous  hyphs.  There  are  some  fungi  in 
which  the  hyphal  form  of  thallus  is  not  present.  The  yeasts  are  either 
single  ellipsoidal  cells,  or  these  cells  are  loosely  connected  together  in 
a  chain  of  bed-like  cells.  These  chains  are  due  to  the  budding  or 
sprouting  method  of  cell  multiplication  where  a  bud,  gemma,  or  sprout, 
grows  out  from  the  mother  cell  as  a  daughter  cell.  It  in  turn  buds 
producing  a  granddaughter  cell  and  so  forth.  Such  a  method  of 
reproduction  is  known  as  gemmation. 

In  the  parasitic  fungi,  the  hyphae  run  either  into  the  cells,  through 
the  cells  (intracellular),  or  between  the  cells  (intercellular).  Where 
the  hyphae  are  intercellular,  short  branches  may  be  formed  which 
penetrate  the  host  cells.  These  short  branches  take  various  forms  and 
are  known  as  haustoria;  a  single  one  as  an  haustorium  (Figs.  36  and  67). 
Occasionally  in  the  mildews,  the  mycelium  may  be  superficial  and 
hence  epiphytic,  while  the  mycelia  which  are  internal  are  endophytic. 
These  are  useful  terms  when  describing  the  parasitic  habits  of  fungi. 
Some  of  the  groups  of  fungi  have  mycelia  that  form  resting  bodies 
of  hyphae.  These  are  the  most  compact  of  all  forms  of  mycelia  and 
are  known  as  sclerotes  {sclerotium — ia),  which  in  many  cases  assume 
tuberous  forms.  They  are  resting  states  of  the  mycelia  and  act  as 
stores  of  reserve  material.  These  are  some  of  the  principal  forms  of 
the  vegetative  thallus  of  the  fungi.  Further  details  will  be  given  in 
he  discussion  which  follows.     Some  sudden  epidemics  of  rust  fungi 


CHARACTERISTICS    OF    THE    TRUE   FUNGI  49 

have  been  ascribed  by  Eriksson  to  the  presence  of  the  protoplasm  of 
the  rust  mixed  with  the  protophism  of  the  host.  To  this  included 
fungous  protoplasm  he  gave  the  name  mycoplasm. 

Some  fungi  are  symbiotic,  that  is,  they  are  found  in  intimate  re- 
lation with  chlorophyll-containing  plants  and  obtain  from  them  food 
of  a  carbonaceous  character,  but  without  apparently  injuring  the 
green  symbiont.  When  they  live  with  algae,  they  commonly  form 
lichens;  or  if  in  connection  with  the  roots  of  trees,  orchids;  and  in 
prothallia  they  form  what  is  known  as  mycorhiza  (Fig.  16). 

The  spores  or  reproductive  cells  of  fungi  may  be  of  two  kinds: 
non-sexual  spores  and  sexual  spores.  The  non-sexual  spores  are  cells 
which  are  formed  vegetatively.     They  are  cells  which  take  special 


Fig.  16. — Ectotrophic  mycorhizas.  At  left  hyphal  mantle  on  root  of  hickory 
Carya  ovata  in  cross  section;  at  right  root  tip  of  an  oak,  Quercus,  with  fungous  mantle. 
{From  Gager,  after  W.  B.  McDougall.) 

forms  in  the  different  groups  of  fungi  and  are  produced  as  special  cells 
in  a  purely  vegetative  manner.  They  represent  a  special  part  of  the 
thallus  given  over  to  reproduction.  Upon  the  formation  of  these 
spores,  which  may  germinate  at  once  or  live  for  some  time  as  resting 
spores,  the  rapid  multiplication  of  the  fungi  depends.  It  is  the  innu- 
merable quantity  of  these  non-sexual  spores  upon  which  an  epidemic 
of  some  particular  fungous  disease  may  depend.  Only  the  most  general 
characters  of  the  various  kinds  of  spores  can  be  discussed  in  an  intro- 
duction of  this  kind.  The  special  kinds  will  receive  due  attention  as 
we  proceed.  Spores  which  are  cut  off,  or  pinched  off,  in  concatenation 
from  the  end  of  a  vertical  hypha,  are  known  as  conidios pores.  In  the 
rusts  such  conidiospores  become  nredospores,  and  in  the  mushrooms 
basidiospores.  Where  the  non-sexual  spores  are  formed  in  a  spore  case, 
4 


50  MYCOLOGY 

or  sporangium,  they  may  be  termed  sporangiospores  (Fig.  13,/).  Fre- 
quently spores  are  formed  by  a  modification  of  certain  cells  of  the  hy])lial 
branch.  These  spores  are  usually  thick-walled,  as  in  the  smuts,  and 
become  known  as  chlamydos pores.  Where  the  whole  hypha  is  divided 
up  into  a  chain  of  spores  one  after  the  other  in  close  order,  such  spores 
are  called  oidiospores.  Special  receptacles  are  associated  with  the 
formation  of  the  non-sexual  spores.  These  are  found  in  the  sac  fungi, 
ASCOMYCETALES,  where  the  depressed  conceptacle  becomes  a  pycnidium, 
or  conidial  fruit,  and  the  spores  which  it  contains  are  pycnidiospores, 
pycnospores,  pycnoconidia  or  the  stylospores  of  Tulasne.  This  form  of 
conidial  fruit  is  surrounded  by  a  firm  wall  or  peridium.  The  pycnidia 
may  be  depressed  in  the  tissues  of  a  host  plant  or  elevated  above  its 
surface,  as  the  case  may  be.  In  some  fungi  the  conidiophores,  in- 
stead of  being  separate,  are  arranged  in  parallel  order,  side  by  side, 
at  an  early  stage,  and  thus  are  united  into  a  fascicle  to  which  the  name 
coremium  has  been  applied. 

The  principal  sexually  produced  spores  in  the  fungi  are  zygospores, 
oospores  and  ascospores.  The  first  two  forms  are  found. in  the  sub- 
class PHYCOMYCETES. 

Their  formation  proceeds  in  such  a  manner  that  the  zygospores  are 
produced  isogamously,  that  is,  by  the  union  of  two  similar  cells,  while 
the  oospores  are  heterogamous,  that  is,  they  are  produced  by  a  union  of 
an  egg  cell  and  a  sperm  cell.  Hence,  we  distinguish  two  orders  of 
the  PHYCOMYCETES,  namely,  the  ZYGOMYCETALES  and  the 
OOMYCETALES,  the  first  showing  isogamy  and  the  latter  heterogamy. 
Details  will  be  given  when  these  orders  are  considered  in  detail.  Until 
recently,  it  was  believed  that  sexuality  did  not  exist  in  the  sac  fungi, 
ASCOMYCETALES,  but  recent  research  has  shown  that  the  nuclei 
of  two  adjoining  cells  unite  and  this  is  followed  by  the  formation  of  a 
spore  sac,  or  ascus,  containing  sac  spores,  or  ascospores.  The  formation 
of  the  asci  is  usually  associated  with  the  production  of  definite  fruit 
bodies.  It  is  doubtful  whether  sexuality  is  found  in  any  of  the  other 
groups  of  fungi.  Curious  nuclear  fusions  in  the  rusts  have  been  sug- 
gested as  a  sexual  union,  but  it  is  safer  to  await  future  discoveries 
before  adopting  such  a  position.  However,  there  are  fungi  in  which 
sexual  organs  seem  to  be  lost  entirely  and  many  of  these  belong  to  the 
most  highly  developed  forms  where  the  thallus  and  fructifications  are 
of  a  complex  type.     The  whole  trend  of  evolution  in  the  fungi  is  for 


CHARACTERISTICS    OF    THE    TRUE    FUNGI  5 1 

the  reduction  in  size  and  importance  of  the  sexual  organs,  until  they 
have  disappeared  completely.  This  may  be  a  result  of  the  perfect 
manner  in  which  the  dififerent  specific  types  are  reproduced  and  multi- 
plied by  the  various  kinds  of  non-sexual  spores  found  in  the  different 
fungous  groups. 


CHAPTER  VI 
HISTOLOGY  AND  CHEMISTRY  OF  FUNGI 

Histology. — Naked  cells  which  are  destitute  of  a  cell  wall  and  con- 
sist of  naked  protoplasm  occur  as  motile  cells  in  only  two  unimportant 
groups  of  the  OOMYCETALES.  The  cell  wall  of  fungi  does  not 
appear  from  the  results  of  numerous  workers  upon  its  chemistry 
to  be  of  the  same  nature  in  the  different  groups  of  them.  A  general 
term  which  has  been  in  current  use  and  which  was  first  suggested 
by  A.  de  Bary  is  that  of  fungous  cellulose,  but  that  term,  as  far 
as  indicating  the  chemic  character  of  the  membrane  is  concerned,  is 
a  misnomer.  It  has  its  correct  application,  if  we  employ  the  term  in 
the  sense  of  fungous  membrane  substance.  We  owe  to  C.  van  Wis- 
selingh  (1898)  the  examination  of  about  a  hundred  species  from  nearly 
all  of  the  orders  and  most  of  the  families  of  EUMYCETES.  Wissehngh 
could  detect  the  presence  of  cellulose  with  certainty  only  in  two  families, 
the  Saprolegniace^  and  the  Peronosporace^.  This  carbohydrate 
could  not  be  detected  either  in  the  ZYGOMYCETALES  or  in  any 
of  the  MYCOMYCETES  examined,  and  especially  was  it  found  to  be 
absent  in  the  yeast  Saccharomyces  cerevisia.  The  researches  of 
Winterstein,  Gilson  and  Wisselingh  proved  that  chitin  formerly  sup- 
posed to  be  of  animal  origin  was  found  in  the  membranes  of  fungi. 
With  the  exception  of  the  two  families  mentioned  above,  the  bacteria 
and  the  yeasts,  chitin  has  been  detected  in  all  other  species  of  fungi 
examined,  e.g.,  Mucor  mucedo,  M.  racemosus,  Rhizopus  nigricans, 
Penicillinm  glaucum,  Trichothecium  roseum,  in  the  sclerotia  of  Botrytis 
cinerea  and  Claviceps  purpurea.  We  do  not  know  at  present  of  the 
simultaneous  occurrence  of  cellulose  and  chitin  in  the  same  cell  wall. 
E.  Winterstein  has  found  true  hemicellulose  in  certain  fungi  and  other 
chemic  substances  have  been  reported  such  as  carbohydrates  of  the 
pentosan  group,  pectose,  callose,  etc. 

The  outer  layers  of  the  wall,  in  some  fungi  (Tremellace^)  may  be 
mucilaginous,  so  that  it  is  resolved  into  a  soft  gelatinous  mass.  Lignifi- 
cation  has  been  reported  in  the  large  pileated  fungi  though  whether 

52 


HISTOLOGY   AND   CHEMISTRY    OF   FUNGI  53 

the  presence  of  lignin  is  proved  thereby  must  remain  an  open  ques- 
tion. Deposits  and  incrustations  of  calcium  oxalate  crystals  are  found 
in  the  membranes  of  fungi,  as  the  spicules  in  the  sporangial  wall  of 
Mucor  mucedo. 

The  cell  contents,  or  protoplasm,  of  fungi  may  be  divided  into 
cytoplasm  with  its  inclusions  and  nucleoplasm.  The  cells  contain 
either  a  single  nucleus  (Erysiphe),  two,  as  in  Exoascus,  or  several, 
as  in  the  mycelial  cells  of  Penicillium  glaticum  and  Peziza  convexula. 
The  hyphae  of  many  contain  numerous,  sometimes  over  hundreds 
of  nuclei  (PHYCOMYCETES).  The  structure  of  the  nucleus  in 
basidia  as  described  by  Wager  agrees  with  that  of  the  higher  flowering 
plants.  It  has  a  nuclear  membrane,  nucleolus  and  nuclear  network  of 
threads  coiled  in  a  loose  knot.  Chromatin  granules  occur.  The  nucleus 
undergoes  division  either  by  fission,  or  by  karyokinesis,  as  first  observed 
by  Sadebeck.  Chromosomes  are  formed  from  the  chromatin  bodies 
when  the  nucleus  begins  to  divide.  A  reduction  of  chromosomes  has 
been  observed  by  Stevens.  Fats  and  oils  are  present  in  fungous  cells 
and  are  found  in  the  form  of  drops  or  globules.  Glycogen  has  been  de- 
tected in  the  spore  sacs  of  the  ASCOMYCETALES.  Volutin  is  a 
name  given  by  Meyer  to  a  reserve  substance  which  contained  C,  H,  O,  N 
and  P  atoms.  Mannite,  trehalose  and  glucose  have  been  found  in 
many  fungi  by  Bourquelot.  Special  substances  of  a  poisonous  nature 
such  as  ergotin,  muscarin,  phalhn  are  of  special  significance  in  cer- 
tain fungi. 

Colors. — Full  details  regarding  the  coloring  matters  in  fungi  will 
be  found  in  Zopf's  "Die  Pilze  in  morphologischer,  physiologischer, 
biologischer  und  systematischer  Beziehung,"  1890.  Clear  bright 
colors  are  present  in  such  species  as  Peziza  aurantia,  P.  coccinea. 
Russula  virescens,  has  a  cap  with  shade  of  green  lighter,  or  darker,  in 
individual  specimens.  Russula  emetica  is  red.  Blue  is  the  predominat- 
ing color  in  the  genus  Leptonia.  Armillaria  mellea  has  a  honey- 
brown,  or  yellow  color.  The  violet  color  of  Cortinarius  violaceus  is 
well  known.  The  color  in  a  number  of  fleshy  fungi  changes  when  the 
fruit  bodies  are  broken,  injured  or  exposed  to  the  air.  This  change  of 
color  is  due  to  an  oxidizing  enzyme.  The  flesh  of  a  number  of  species 
of  Boletus  changes  from  white  or  yellow  to  a  deep  indigo-blue  when 
broken,  or  abraded.  The  deliquescence  of  species  of  the  genus 
Coprhius,  when  the  color  changes  from  white  to  black  with  the  melting 


54  MYCOLOGY 

down  of  Lhe  whole  fruit  body  has  been  proved  to  be  a  process  of  auto- 
dig^estion.  When  the  hyphae  are  colored,  the  color  is  confined  generally 
to  the  cell  wall,  although  Biffen  states  that  in  some  hyphae  the  color 
is  located  in  the  contents,  the  wall  remaining  colorless.  Spores  are 
colored  frequently  as  in  Ascobolus  which  grows  on  manure.  The  spores 
at  first  colorless  change  through  pale  lilac  to  clear  deep  amethyst.  The 
coloring  matter  is  confined  to  the  spore  walls,  but  in  some  cases  the 
contents  are  colored,  while  the  wall  is  colorless,  as  in  many  a^ciospores. 

Physiology  or  Fungi 

The  research  of  recent  years  in  the  nutrition  of  fungi  has  shown 
that  nine  chemic  elements  are  necessary  for  the  structure  and  complete 
development  of  the  true  fungi.  These  elements  are  carbon,  hydrogen, 
oxygen,  nitrogen,  sulphur,  phosphorus,  potassium  (or  rubidium), 
magnesium  and  iron.  Analysis  of  the  ash. constituents  of  fungi  shows 
that  phosphoric  acid  and  potassium  are  the  chief  ones,  the  latter  form- 
ing seldom  less  than  one-quarter  and  sometimes  one-half  of  the  total. 
Phosphorus  is  present  in  the  ash  to  the  extent  of  15  to  60  per  cent, 
and  is  eagerly  absorbed  by  growing  fungi,  as  is  shown  by  Dcedalea 
quercina,  which  in  its  growth  completely  extracted  the  phosphoric 
acid  from  decayed  wood.  Winogradsky,  Meyer,  H.  Molisch  and  W. 
Benecke  have  shown  that  magnesium  is  indispensable  to  fungi.  Be- 
necke  has  demonstrated  a  considerable  difference  in  development  shown 
by  two,  otherwise  equal,  specimens,  the  one  grown  without  magnesium 
and  the  other  in  a  medium  containing  0.0025  mg-  of  crystallized  magnes- 
ium sulphate  per  25  c.c.  and  Guenther  has  proved  that  0.005  "^g-  of 
magnesium  sulphate  was  necessary  to  induce  a  sowing  of  Rhizopus 
nigricans  to  grow  at  all. 

As  to  iron,  as  an  indispensable  element  before  the  matter  was  put 
to  the  test,  it  was  thought  that  fungi  being  chlorophylless  did  not 
require  iron  like  the  green  plants  in  which  iron  was  concerned  in  the 
formation  of  chlorophyll.  The  experiments  of  Hans  Molisch  tend  to 
prove  the  essential  importance  of  iron  in  the  nutrition  of  the  true  fungi 
for  in  presumably  iron-free  cultures,  the  spores  of  Aspergillus  niger 
did  not  develop  beyond  the  formation  of  a  sickly  mycelium.  Similar 
results  were  obtained  with  sowings  of  pressed  yeast  cells,  spores  of 
Mucor  racemosus  and  a  species  of  Penicillum.     Iron  in  addition  to 


HISTOLOGY    AND    CHEMISTKY    OF    FUNGI  55 

being  a  nutritive  material  also  acts  as  a  stimulant.  The  position  of 
sulphur,  as  an  important  nutritive  element,  is  doubtful.  It  is  inferred 
that  because  this  element  forms  an  important  constituent  of  the  albu- 
minoids, that  it  is,  therefore,  essential  to  fungi,  but  there  are  no  re- 
liable experiments  which  prove  that  to  be  so.  Awaiting  more  detailed 
investigations,  sulphur  has  been  included  in  the  above  list  of  nutri- 
tive elements.  The  source  of  the  C,  H,  and  O  which  form  such  an 
important  part  of  the  food  of  fungi  is  the  dead  or  Hving  bodies  of  other 
plants  and  animals,  principally  plants  in  which  are  found  sugars, 
starch,  cellulose,  mannite,  citric  acid,  and  other  bodies  of  organic  origin. 
The  source  of  nitrogen  is  similarly  from  soluble  nitrogenous  bodies, 
peptones,  propylamin,  asparagin  and  others,  but  few  if  any  of  the 
higher  fungi  can  utihze  free  atmospheric  nitrogen,  as  can  the  bacteria 
which  form  the  nodules  on  the  roots  of  leguminous  plants,  described  in 
a  former  section  of  this  book.  The  various  culture  media  on  which 
bacteriologists  and  mycologists  cultivate  successfully  a  large  series  of 
bacteria  and  fungi  will  be  considered  in  a  subsequent  chapter.  Modern 
research  along  the  lines  of  technique  has  demonstrated  many  im- 
portant points  about  the  growth  and  nutrition  of  the  higher  fungi 
and  these  will  be  discussed,  as  we  proceed  to  the  end  of  the  book. 

The  chemic  investigation  of  the  fungi  began  with  the  refinements 
in  the  technique  of  modern  organic  chemistry  and  much  has  been  pub- 
lished on  the  subject,  so  that  there  is  a  bibliography  too  voluminous  to 
give.  Much  of  the  most  important  chemic  work  on  fungi  published 
prior  to  1890  will  be  found  in  Zopf's  "Handbook."  No  general  work 
of  this  kind  has  recently  appeared,  so  that  we  must  depend  on  recent 
original  papers  on  the  chemistry  of  fungi,  and  in  part  on  the  statements 
of  Zopf's  great  book.  The  following  inorganic  elements  have  been 
found  in  fungi:  chlorine,  sulphur,  phosphorus,  sihcon,  potassium, 
sodium,  lithium,  calcium,  magnesium,  aluminium,  manganese  and 
iron.  Manganese  has  been  found  in  the  cap  of  Lactarius  piperatus. 
Aluminium  has  been  reported  as  occurring  in  the  ash  of  lichens.  The 
mean  of  a  number  of  analyses^  of  mushroom  {Agaricus  campestris), 
truffle  (Tuber),  Morchella  esculenta,  two  other  species  of  MorcheUa, 
species  of  Boletus,  a,nd  Polyporus  officinalis  is  as  follows:  potassium  45 
per  cent.,  phosphoric  acid  40  per  cent.,  magnesia  2  per  cent.,  sodium 
1.4  per  cent.,  calcium  1.5  per  cent.,  iron  oxide  i  per  cent.,  silicic  acid 

'ZoPF,  Wilhelm:  Die  Pilze:  ii8. 


56  MYCOLOGY 

I  per  cent.,  sul])huric  acid  8  per  cent.,  chlorine  i  per  cent.  The  organic 
compounds  of  the  carbohydrate  group  found  in  fungi  are  cellulose, 
grape  sugar,  glycogen  and  kinds  of  gums,  mannit,  inosit,  and  several 
other  less  important  ones.  The  organic  acids  include  oxalic,  malic, 
acetic,  citric,  formic,  lactic,  helvelhc,  and  propionic  acid,  as  well  as  other 
less  well-known  acids. 

Fats  and  oils  are  often  present  as  reserve  substance  in  many  repro- 
ductive spores,  as  in  oospores,  zygospores,  ascospores,  and  the  like. 
Large  quantities  are  also  often  present  in  the  mycelium,  as  in  Lactarius 
deliciosus,  which  contain  6  per  cent.  (5.86  per  cent.).  Fat  is,  as  a  rule, 
not  entirely  absent  from  any  species  of  fungus.  Fliickiger  gives  the 
fat  content  of  the  sclerotium  of  Clavkeps  purpurea  as  35  per  cent.  The 
mushroom  Agariciis  campestris  has  0,18  per  cent,  and  Helvella  esculent  a 
1.65  per  cent. 

Resin  occurs  in  fungi  in  the  form  of  excretions,  partly  as  infiltra- 
tion of  the  cell  walls,  partly  as  contents  of  the  living  cells.  The  intense 
orange-yellow  color  of  the  caps  and  stipe  of  the  Agaricus  (Pholiota) 
spectabilis,  according  to  Zopf,  as  also  the  pale  yellow  of  the  gills  and 
the  flesh  of  cap  and  stipe  together  with  the  ochre-yellow  color  of 
the  masses  of  spores  is  due  to  the  presence  of  a  resin  acid  which  is 
present  as  a  hyphal  cell  content.  Pigments  of  various  kinds  classified 
by  Zopf  are  also  found.  Besides  the  important  substances  mentioned 
above,  chemists  have  found  coniferin,  muscarin,  trimethylamin  (spores  of 
Tilletia  caries),  ergotin,  cholin,  phallin,  cholesterin.  Several  of  these 
will  be  discussed  in  connection  with  the  poisonous  or  non-poisonous 
character  of  certain  of  the  fleshy  fungi. 

Enzymes  {Jev^vjjios,  leavened,  from  €u,  in  and  ^vp-v,  leaven,  a  term 
first  suggested  by  Kiihne  for  an  unorganized  ferment). — The  study  of 
the  ferments,  or  enzymes,  of  the  fungi  and  higher  plants  has  thrown  a 
flood  of  light  upon  their  metabolic  activity,  for  enzyme  action  is  the 
strategic  center  of  vital  activity.  Pasteur  emphasized  the  role  of  micro- 
organisms as  ferment  producers,  and  that  led  to  the  classification  of 
ferments  into  organized  and  unorganized.  Since  Buchner  discovered 
zymase,  ferments  have  been  divided  into  endocellular  and  extracellular. 
Endocellular  enzymes  as  those  which  cannot  diffuse  out  of  the  cell, 
such  as  zymase,  while  extracellular  enzymes  are  those  which  are  capable 
of  diffusion  out  of  the  cell,  such  as  invertase.  Hepburn  defines  an 
enzyme  as  a  soluble  organic  compound  of  biologic  origin  functioning 


HISTOLOGY    AND    CHEMISTRY    OF    FUNGI  5  7 

as  a  thermolabile  catalyst  in  solution.  In  connection  with  this  defini- 
tion, it  is  important  to  know  that  a  catalytic  agent  is  one  which  alters 
the  rate  of  a  reaction  without  itself  entering  into  the  final  product 
(Ostwald,  1902),  or  which  does  not  appear  to  take  any  immediate  part 
in  the  reaction,  remains  unaltered  at  the  end  of  the  reaction  and  can 
be  recovered  again  from  the  reaction  product  unaltered  in  quantity 
and  quality. 

Enzymes  differ  from  ordinary  inorganic  catalysts  in  their  sensitive- 
ness to  heat  and  light.  They  are  destroyed  at  100°  C,  and  most  of 
them  cannot  be  heated  safely  above  60°  C.^  The  velocity  of  the 
reaction  increases  with  a  rise  of  temperature  up  to  an  optimum  and 
as  the  temperature  is  increased  above  the  optimum  the  enzyme  is 
permanently  inactivated.  Enzymes  retain  activity  even  after  ex- 
posure to  action  of  liquid  air.  Light  in  its  ordinary  form  in  the  pres- 
ence of  oxygen  and  ultraviolet  light  independent  of  oxygen  are  de- 
structive to  enzymes.  Again,  enzymes  possess  most  of  the  important 
properties  of  colloidal  solutions,  such  as  their  non-diffusibility.  They 
are  soluble  in  water,  in  dilute  salt  solutions,  or  in  glycerin.  They 
exhibit  the  phenomenon  of  adsorption. 

An  important  discovery  has  recently  been  made  which  has  thrown 
considerable  light  on  the  activity  of  enzymes,  and  that  has  been  the 
stimulation  exercised  by  certain  substances  which  have  been  called 
activators  and  the  inhibition  exercised  by  other  substances,  which  have 
been  called  paralyzers.  The  activators  are  in  some  cases  simple  chem- 
ical substances,  such  as  acids,  alkalis  and  salts,  or  they  are  complex 
bodies  of  unknown  chemic  character,  but  they  have  this  in  common  that 
they  can  be  separated  from  the  enzyme  by  dialysis,  and  are  not  de- 
stroyed by  heating.  An  enzyme  may  be  rendered  inactive  by  the 
removal  of  its  activator,  but  it  can  be  restored  to  activity  by  mixing 
again  with  this  substance.  In  the  case  of  some  enzymes,  the  inactive 
substance,  as  it  is  formed  in  a  cell  may  be  called  a  zymogen,  or  profer- 
ment, but  when  associated  with  the  activator  the  active  enzyme  is 
developed.  An  activator  is  inorganic.  A  kinase  is  a  more  or  less 
complex  organic  body  which  activates  a  proferment. 

Substances  which  reduce,  or  destroy,  the  activity  of  enzymes  are 
called  paralyzers,  which  may  be  formed  as  products  of  enzymatic 

'Haas,  Paul,  and  Hill,  T.  G.:  An  Introduction  to  the  Chemistry  of  Plant 
Products.  1913:  340-341. 


58  MYCOLOGY 

aclivity  or  be  foreign  substances.  Acetic  and  lactic  acids  formed  by 
enzyme  activity  will  destroy  the  ferments  producing  them  unless 
neutralized.  Among  foreign  substances  which  act  as  paralyzers 
may  be  mentioned  formaldehyde,  mercuric  chloride,  alcohol,  chloro- 
form and  hydrocyanic  acid.  Anti-enzymes  are  a  class  of  substances, 
which  are  antagonistic  to  the  action  of  enzymes.  The  distribution  of 
the  enzymes  in  the  various  groups  of  fungi  including  the  slime  moulds, 
bacteria  and  true  fungi  have  been  investigated  by  a  number  of  zymolo- 
gists.  For  example,  Monilia  sitophila  may  form  maltase,  trehalase, 
raffinase,  invertase,  cytase,  diastase,  lipase,  tyrosinase  and  trypsin. 
Dox^  has  demonstrated  in  moulds,  the  following:  protease,  nuclease, 
amidase,  lipase,  emulsin,  amylase,  inulase,  raffinase,  sucrase,  maltase, 
lactase,  histozyme,  catalase  and  phytase,  and  he  has  found  that  these 
enzymes  are  formed  regardless  of  the  chemic  character  of  the  substratum. 
Without  going  into  all  the  details  of  the  occurrence  of  enzymes  in  the 
fungi,  the  following  classification  of  the  principal  enzymes  found  in  the 
various  groups  may  prove  useful  to  the  student. 

Classification  or  Enzymes  in  Fungi 
I.  HYDROLYTIC  ENZYMES. 

(a)  Carbohydrate-splitting  enzymes  (carbohydrases)  : 

Amylase,  or  Diastase,  which  hydrolyzes  starch  to  dextrin  and 
maltose.  The  Koji  fungus,  Aspergillus  oryzece  (Taka-diastase). 
Cytase,  which  hydrolyzes  hemicellulose  to  galactose  and  mannose 
in  Botrytis. 

Inulase,  which  hydrolyzes  inuhn  to  levulose. 
Invertase,  which  hydrolyzes  cane  sugar  to  dextrose  and  levulose. 
Saccharomyces,  Fusarium,  Aspergillus  niger. 
Lactase,  which  hydrolyzes  lactose  (milk  sugar)  to  dextrose  and 
galactose.     Kephir  organism. 

Maltase,  which  hydrolyzes  maltose  (malt  sugar)  to  dextrose. 
Saccharomyces  octosporus. 

Raffinase,  which  hydrolyzes  raffinose  to  levulose  and  melitiose. 
Aspergillus  niger. 

Trehalase,  decomposing  trehalose  into  a  reducing  sugar.     Poly- 
porus  sulphiireus. 
1  Dox,  A.  W.:  Enzyme  Studies  of  Lower  Fungi.     Plant  World,  15:  40,  February 
1912. 


HISTOLOGY    AND    CIIEMISTKY    OF    FUNGI  59 

(b)  Protein-splitting  enzymes  (proteases): 

Pepsin,  which  hydrolyzes  proteins  to  albumoses  and  peptones. 
Trypsin,  which  hydrolyzes  proteins  to  peptides  and  amino- 
acids  in  A  maniia  muscaria  and  Boletus  edulis. 

(c)  Urea-splitting  enzymes  (ureases): 

Urease  obtained  from  Micrococcus  urcce,  which  hydrolyzes  urea 
into  ammonia  and  carbon  dioxide. 

(d)  Nuclease,  which  spHts  nucleic  acid. 

(e)  Fat-splitting  enzymes  (esterases  and  lipases): 

Lipase  in  Penicillium  glaucum  and  Aspergillus  niger,  also 
Empusa.    Phycomyces,  which  break  up  fatty  oils. 

(/)  Glucoside-splitting  enzymes: 

Emulsin,  which  hydrolyzes  amygdalin  to  glucose,  hydrocyanic 
acid  and  benzaldehyde.  Also  such  other  glucosides  as  saUcin, 
populin,  coniferin  which  fungi  are  able  to  utilize. 

2.  FERMENTING  ENZYMES. 

(a)  Alcoholic  fermentation  of  glucose,  levulose,  mannose,  etc.,  by 

zymase  in  yeasts. 
{b)  Lactic  acid  fermentation  of  lactose  by  lactic  acid  bacteria, 
(c)  Butyric  fermentation  of  lactose  by  the  butyric  acid  bacteria. 

3.  Clotting  Enzymes  (Coagulation,  CurdUng). 

Rennin  (Chymosin),  which  curdles  milk.  Bacillus  mesentericus 
vulgatus. 

4.  OXIDIZING  ENZYMES. 

(a)  Oxidases,  which  oxidize  alcohols  to  acids,  e.g.,  the  action  of 

Mycoderma  aceti,  etc. 
{b)  Tyrosinase.     Russula  nigricans  and  species  of  Boletus,  Lacta- 

rius,  etc. 
(c)  Peroxidases,  which  set  free  oxygen  from  hydrogen  peroxide, 

causing  this  substance  to  blue  guaiacum  resin. 
{d)  Catalase,   which    decomposes    hydrogen    peroxide    with    the 

evolution  of  molecular  oxygen. 

In  concluding  this  brief  study  of  the  enzymes  it  may  be  stated  that 
they  can  be  detected  by  chemic,  bacteriologic,  serologic  and  histologic 


6o  MYCOLOGY 

means.     Details  of  the  occurrence  of  the  above  enzymes  will  be  found 
in  the  books  noted  in  the  footnote  below.' 

CHEMOTAXIS 

The  attraction  or  repulsion  of  motile  microorganisms  by  chemical 
stimulants  known  as  chemotaxis  is  found  in  the  activity  of  the  zoospores 
of  the  OOMYCETALES  and  in  the  growth  of  the  hyphae  of  fungi  in  gen- 
eral toward  or  away  from  the  stimulus.  To  these  phenomena  the  names 
of  positive  and  negative  chemotropism  have  been  given.  The  thorough 
investigations  of  M.  Miyoshi  with  Aspergillus  niger,  Mucor  mucedo, 
Penicillium  glaucum,  Phycomyces  nitens,  Rhizopus  nigricans  have  shown 
that  the  following  substances  act  as  powerful  stimulants:  ammonium 
phosphate,  asparagin,  dextrin,  saccharose  and  glucose.  The  threshold 
value  (marginal  limit)  or  minimum  quantity  capable  of  producing  a 
chemotactic  effect  was  ascertained  by  Miyoshi  as  o.oi  per  cent,  in 
the  case  of  glucose  acting  on  Mucor  mucedo.  On  gradually  increasing 
the  dose,  a  second  limit  is  reached  where  repulsion  occurs.  The 
entrance  of  fungi  into  leaves  and  the  growth  of  hyphae  along  certain 
lines  inside  of  the  host  tissue  and  the  formation  of  haustoria  are  per- 
haps all  indications  of  chemotropic  response. 

iRayliss,  W.  M.:  The  Nature  of  Enzyme  Action  (Monograph  on  Biochem- 
istry).    Longmans,  Green  &  Co.,  1914. 

Green,  J.  Reynolds:  The  Soluble  Ferments  and  Fermentation.  Cambridge 
at  the  University  Press,  1899. 

Haas,  Paul  and  Hill,  T.  G.  :  An  Introduction  to  the  Chemistry  of  Plant  Prod- 
ucts.    London,  Longmans,  Green  &  Co.,  1913. 

Harden,  Arthur:  Alcoholic  Fermentation  (Monograph  on  Biochemistry). 
London,  Longmans,  Green  &  Co.,  1914. 

Lafar,  Franz,  transl.  by  Salter,  Charles,  T.  C:  Technical  Mycology,  ii, 
Pt.  I  :  61-65. 

Marshall,  Charles  E.  and  others:  Microbiology.  Philadelphia,  P.  Blakiston's 
Son  &  Co.,  1911 

Oppenheimer,  Carl:  Die  Fermente  und  ihre  Wirkungen.     Leipzig,  1903. 

Vernon,  H.  M.  Intracellular  Enzymes.     London,  John  Murray,  1908. 


CHAPTER  VII 
GENERAL  PHYSIOLOGY  OF  FUNGI 

The  influence  of  light  on  the  development  of  the  EUMYCETES 
has  been  investigated  by  a  number  of  workers.  The  influence  of  light 
on  the  direction  of  growth  is  known  as  phototropism.  On  account  of 
the  contradictory  evidence  of  earlier  investigations,  Friedr.  Oltmanns 
experimented  with  Phycomyces  nitens  using  a  powerful  electric  arc  light. 
He  found  that  Phycomyces  behaved  positively  phototropic  under  weak 
illumination,  but  negatively  so  under  a  powerful  light.  It  remained 
aphototropic  with  an  intermediate  illumination,  and  in  young  sporangial 
hyphse  with  gray  sporangia,  a  given  degree  of  illumination  caused 
attraction,  while  with  older  sporangiophores  with  blackened  sporangia 
repulsion  was  noticed.  The  germination  of  the  spores  of  such  fungi,  as 
Penicilliwn  glaucum,  Trichothecium  roseum,  Fusariiim  heterosporium, 
Rhizopus  nigricans,  does  not  seem  to  be  affected  by  light;  while 
von  Wettstein  found  that  light  retarded  the  germination  of  the  spores 
of  Rhodomyces  Kochii.  The  evidence  as  to  the  influence  of  light  on 
the  vegetative  development  seems  to  be  contradictory.  J.  Schmitz 
found  that  Spharia  carpophila  grew  better  in  the  dark  than  in  daylight. 
G.  Winter  found  Peziza  Fuckeliana  to  cease  growth  in  the  dark  and  the 
fungus  perishes  if  light  be  long  excluded.  Mac  DougaP  experimented 
with  Coprinus  stercorarius.  He  found  that  it  developed  a  much  greater 
length  than  the  normal  in  darkness,  but  the  fruit  bodies  remained  in 
a  rudimentary  or  incomplete  stage.  After  growth  had  proceeded  in 
this  manner  for  some  time  the  illumination  of  the  body  was  followed 
by  the  production  of  fruit  bodies  in  a  manner  demonstrating  most 
conclusively  that  the  action  in  question  was  due  to  a  purely  stimula- 
tive action  of  light,  since  the  rays  did  not  participate  in  any  synthesis 
of  material. 

The  rate  of  cell  reproduction  does  not  seem  to  be  influenced  by  the 
presence   or  absence  of  light.     In   many  fungi,   the  formation  of  a 

1  Mac  Dougal,  D.  T.  :  The  Influence  of  Light  and  Darkness  upon  Growth  and 
Development.     Memoirs  of  the  New  York  Botanical  Garden,  ii  (1903:  279). 

61 


62  MYCOLOGY 

fructification  does  not  seem  to  be  affected  by  the  light  conditions, 
but  here  the  evidence  is  contradictory,  some  fructifications  being 
formed  better  in  light  than  in  the  dark  and  vice  versa.  Kolkwitz  after 
eliminating  various  sources  of  error  of  earlier  experimenters  found 
that  in  his  cultures  of  Aspergillus  niger  and  Oidium  ladis  that  con- 
siderable acceleration  of  respiration  is  experienced  with  a  brief  illumina- 
tion by  a  powerful  electric  arc.  Koernicke^  finds  that  Roentgen  rays 
inhibit  the  growth  of  fungi  with  prolonged  action. 

Luminosity  of  Fungi. — The  luminosity  of  wood  and  decaying  logs 
in  the  forest  is  associated  with  the  mycelia  of  certain  fungi.  The 
phenomenon  is  connected  frequently  with  gill-bearing  fungi,  such 
as  Agaricus,  Armillaria  mellea,  Pleurotus  olearius,  and  as  determined  by 
Molisch  with  the  two  ascomycetous  fungi.  Xylaria  hypoxylon  and  A^. 
Cookei.  In  order  to  prevent  any  error  arising  in  the  experiments 
through  the  presence  of  luminous  bacteria,  Molisch^  grew  Armillaria 
mellea,  Xylaria  hypoxylon,  X.  Cookei,  Mycelium  X.  in  pure  cultures, 
the  latter  succeeding  well  on  bread.  He  found  that  under  such  con- 
ditions the  plants  became  phosphorescent.  Such  phosphorescence 
is  connected  with  a  supply  of  oxygen  and  is  not  due  to  the  separation 
of  some  luminous  substances,  but  is  intracellular  in  its  origin. 

Liberation  of  Spores.— The  spores  of  the  gill  fungi  (HYMENOMY- 
CETES)  are  very  adhesive,  when  freshly  set  free.  As  a  result  of 
this,  special  arrangements  are  found  for  the  liberation  of  the  spores 
from  the  surfaces  of  the  gills  and  the  hymenial  tubes.  Paraphyses 
between  the  special  conidiophores  known  as  basidia  serve  to  increase 
the  spaces  between  the  spores,  preventing  contact  and  allowing  a 
freer  fall  of  the  spores.  The  arrangement  of  the  gills  is  such  as  to 
economically  increase  the  spore-bearing  surface,  and,  therefore,  the 
total  number  of  spores  that  a  fruit  body  can  produce.  By  various 
growth  movements  of  the  cap  and  fruit  stalk,  the  spore-bearing  sur- 
face is  placed  in  the  best  possible  position  for  the  liberation  of  spores. 
The  spores  liberated  from  the  gills  on  the  under  surface  of  a  pileus 
placed  over  a  horizontal  sheet  of  paper  fall  vertically  downward  and 
form  a  spore  print,  which  consists  of  radiating  lines  corresponding  to 
the  inter-lamellar  spaces.  The  number  of  spores  set  free  by  large 
fruit  bodies  is  prodigious.     A  specimen  of  the  mushroom  Agaricus 

1  KoERNiCKE,  Max:  Ber.  d.  deutsch.  Bot.  Ges.,  1904:  22,  14H. 

2  Molisch,  Hans:  Leuchtende  Pflanze,  1904:  25-46. 


GENERAL   PHYSIOLOGY    OF    FUNGI 


63 


{PsalUota)  campestris  with  a  diameter  of  8  cm.  produced  1,800,000,000 
spores,  one  of  Coprimis  annatus  5,000,000,000  and  one  of  Polyporiis 
sqnamosus  11,000,000,000  spores.  Buller  has  estimated  that  a  large 
fruit  body  of  the  giant  puffball  Lycopcrdon  bovisla  (40  X  28  X  20  cm.) 


Fig.  17. — Diagram  of  the  discharge  of  spores  from  a  fruit-body  of  Polyslictus 
versicolor  as  seen  by  a  beam  of  light.  A  stream  of  spores  is  carried  round  within 
the  beaker  very  slowly  by  convection  currents  and  recorded.  Reduced  about  2/3. 
{After  Buller:  Researches  on  Fungi,  1909:  97.) 

contained   7,000,000,000,000  spores,  or  as  many  as  4000  mushrooms 
of  the  size  above  mentioned. 

Spores  dropping  from  any  fruit  body  which  is  suspended  in  a 
closed  glass  chamber  can  be  seen  in  clouds,  or  individually,  without  the 


64  MYCOLOGY 

microscope  by  concentrating  a  beam  of  light  upon  them  (Fig.  17). 
This  is  a  simple  method  of  examining  the  discharge  of  spores  from  the 
mushroom.  It  can  be  used  conveniently  with  the  xerophytic  fruit 
bodies  of  Lcnzitcs  betuUna,  Polystictus  versicolor,  Schizophyllum  com- 
mune at  any  time  in  the  laboratory  by  keeping  them  dry  for  months 
and  reviving  them  by  placing  them  in  a  jar  with  wet  cotton.  They 
quickly  revive  and  begin  to  shed  their  spores  in  six  hours  and  this 
discharge  continues  for  some  days. 

Ordinarily,  spore  discharge  from  any  fruit  body  is  a  continuous 
process,  but  if  placed  in  hydrogen,  or  carbon  dioxide,  the  liberation  of 
spores  ceases  quickly,  demonstrating  that  oxygen  is  necessary.  Ether 
and  chloroform  act   similarly   to   the  gases   above   mentioned.     The 


X  A  B 


"•• 

Fig.  18. — The  successive  and  violent  discharge  of  the  four  spores  from  the  basid- 
ium  of  a  mushroom  Agaricus  (Psalliola)  campeslris.  X,  The  basidium  with  four 
ripe  spores;  A,  B,  C,  D,  successive  stages  of  the  discharge  of  spores  i,  2,  3,  4  respec- 
tively.     (After  Buller,  Researches  on  Fungi,  1909:   144.) 

special  conidiophore,  or  basidium,  usually  bears  four  spores  which  are 
discharged  successively,  each  spore  being  shot  out  violently  by  the 
pressure  of  the  cell  sap  upon  the  wall  of  the  basidium  and  perhaps  also 
on  the  spore  wall  within  a  few  seconds  or  minutes  of  one  another 
(Fig.  18).  The  rate  of  the  fall  was  observed  by  Buller,  who  used  a 
horizontal  microscope  and  a  revolving  drum  to  record  accurately  the 
rate  of  their  fall.  The  rate  of  fall  of  the  spores  of  gill  fungi  ranges  from 
0.3  to  6.0  mm.  per  second.  It  varies  with  the  size,  specific  gravity 
and  the  progress  of  desiccation  of  the  spores.  Buller  found  the  relatively 
small  spores  of  Collybia  dryophila  in  dry  air  to  fall  at  an  average  rate 
of  0.37  mm.  per  second  while  the  relatively  large  spores  of  Amanitopsis 
vaginata  in  a  saturated  chamber  attained  a  speed  of  6.08  mm.  per 


GENERAL    PHYSIOLOGY    OF    FUNGI 


65 


second  and  the  spores  of  the  common  mushroom  shortly  after  leaving 
the  cap  fall  at  the  rate  of  i  mm.  per  second  approximately. 

The  violent  discharge  of  the  spores  prevents  the  adhesive  spores 
from  massing  together  and  from  sticking  fast  to  the  gill  surface.  At 
first  the  spore  is  shot  out  horizontally,  then  under  the  influence  of 
gravity,  it  describes  a  sharp  curve  and  then  falls  vertically.  The 
path  described  by  the  falling  spore  has  been  appropriately  called  a 


Fig.  19. — Amanitopsis  vagineta.  Relations  of  spores  to  the  fruit-body.  A, 
Transverse  section  through  two  gills,  h,  basidia  projecting,  the  arrows  show  spore 
parts  (sporabola),  Magn.  15;  B,  vertical  section  of  hymenium  and  subhymenium,  c, 
paraphyses,  a-c,  basidia  stages,  Magn.  370;  C,  isolated  basidium  with  two  basidios- 
pores;  D,  discharged  spore;  E,  basidium,  Mayer,  mo.      (After  B idler,  1909:  165. )j 

sporabola  (Fig.  19).  There  are  two  distinct  types  of  fruit  bodies  as  to 
spore  production  and  spore  liberation.  These  are  the  Coprinus  comatus 
and  the  mushroom  types.  The  deliquescence,  or  melting  of  the  fruit 
bodies  of  the  Coprini  is  a  process  of  auto-digestion  and  it  assists  mechan- 
ically in  the  discharge  of  the  spores.  Spore  discharge  precedes  deliques- 
cence. The  spores  are  set  free  from  below  upward  and  by  auto-diges- 
tion those  parts  of  the  gills  are  removed  from  which  the  spores  have 
5 


66 


MYCOLOGY 


been  shed,  thus  permitting  the  opening  out  of  the  cap  and  the  freer 
discharge  of  the  remaining  spores.  The  discharged  spores  are  conveyed 
by  the  wind  (Fig.  20).  The  mushroom  type  is  the  usual  kind  where 
the  spores  are  discharged  without  deliquescence. 

The  spores  of  Bulgaria,  Gyromilra,  Peziza  and  others  of  the 
AscoMYCETALES  are  scattered  by  the  wind,  but  those  of  Ascpbolus 
immersus  and  Saccobolus  are  dispersed  by  herbivores.  The  spores  of 
Peziza  repanda,  according  to  Buller,  are  shot  up  into  the  air  to  a 
height  of  2  to  3  cm.  and  leave  the  spore  sac  (ascus)  together,  but 


Fig.  20. — Semidiagrammatic  sketch  in   a  field  with  horse  mushroom,  Agaricus 

{Psalliola )  arvensis,  showing  Hberation  and  discharge  of  spores  horizontally 

and  from  velum.     Reduced  to  y<i.     {After  Buller,  Researches  on  Fungi,  1909:  218.) 


separate  as  they  leave  the  ascus  mouth.  Puffing  is  due  probably  to  a 
stimulus  given'j  to  the*  protoplasm  in  contact  with  the  ascus  Hd,  and 
it  is  observed  when  poisonous  substances  are  applied  such  as  iodine 
mercuric  chloride,  silver  nitrate,  copper  sulphate,  sulphuric  and  acetic 
acids  are  used.  With^some  of  these  forms  the  ascus  may  be  considered 
as  a  squirting  apparatus  by  which  a  jet  of  spores  leaves  its  mouth. 
The  writer^  noted  the  puffing  of  the  spores  in  Peziza  hadia  when  the 
large  saucer-shaped  fruit  bodies  were  held  in  the  hand.  At  intervals 
of  several  minutes  the  puffing  took  place. 

Ascobolus  immersus  as  a  coprophilous  (dung-inhabiting)  fungus  has 
1  Harshberger,  J.  W.:  Journ.  of  Mycol.,  8:  158,  October,  1902. 


GENERAL  PHYSIOLOGY  OF  FUNGI  67 

special  adaptations:  (i)  the  protrusion  of  the  ripe asci  beyond  the  general 
surface  of  the  fruit  body;  (2)  the  diurnal  periodicity  in  the  ripening  of 
successive  groups  of  asci;  (3)  the  positive  heliotropism  of  the  asci;  (4) 
the  considerable  distance  to  which  the  spores  are  ejected  (sometimes 
30  cm.)  with  which  is  associated;  (5)  the  large  size  of  the  asci  and  spores; 
and  (6)  the  clinging  of  the  eight  spores  together,  while  describing  their 
trajectory  through  the  air.  The  forcible  explosion  of  the  sporangio- 
phore  of  Pilobolus  crystallimis  by  which  the  whole  sporangium  is  dis- 
charged a  considerable  distance  into  the  air  is  due  to  the  tension  exerted 
by  gases  and  water  vapor  within  the  swollen  sporangiophore. 

The  escape  of  biciliate  zoospores  (swarm  spores)  in  such  genera  of 
aquatic  fungi  as  Achlya  and  Saprolegnia  is  through  a  terminal  pore  in 
the  zoosporangium.  It  appears  that  the  discharge  is  associated  with 
the  motility  of  the  cilia.  In  the  moulds  (Mucorace^),  the  sporangial 
wall  which  is  coated  with  minute  particles  of  calcium  oxalate  becomes 
soluble  in  water  at  maturity  and  the  intersporal  substance  swells  up 
assisting  in  the  liberation  of  the  spores.  The  entire  inner  peridium 
about  the  size  of  a  pin's  head  is  forcibly  ejected  in  the  gasteromycetous 
fungus,  S phcBrobolus  stellatus,  and  this  is  due  to  the  unequal  tension  of 
the  different  peridial  layers. 

The  disposal  of  spores  and  conidia  is  facilitated  by  water  in  the 
case  of  the  motile  zoospores  of  such  fungi  as  Achlya  prolifera,  Phytoph- 
thora  injestans  and  Saprolegnia  ferax,  where  cilia  come  into  play. 
Many  spores  are  no  doubt  carried  passively  by  water  currents.  Wind 
is,  however,  one  of  the  chief  agents  in  the  distribution  of  fungous  spores, 
such  as  those  of  the  puffballs,  the  rusts  and  the  moulds,  although  the 
distance  that  such  spores  are  carried  is  probably  exaggerated.  Flies, 
which  feed  upon  the  strong-smeUing  slime  in  which  the  minute  spores 
of  such  fleshy  fungi  as  Mutinus  caniniis,  Icthyphallus  impudicus  are 
imbedded,  assist  in  the  carriage  of  such  spores  and  those  of  ergot 
{Claviceps  purpurea)  in  the  Sphacelia  stage,  where  viscid  drops  exude 
that  are  attractive  to  flies,  and  although  some  flies  arekilled  by  it,  yet 
sufficient  escape  to  carry  the  spores.  Slugs  and  snails  by  crawling 
alternately  over  diseased  and  healthy  plants,  probably  disseminate 
spores.  That  birds  serve  as  distributors  of  spores  is  indicated  by  the 
studies  of  Heald  with  the  chestnut  blight  fungus,  Endothia  parasitica, 
in  which  he  found  that  a  single  downy  woodpecker  carried  as  many  as 
657,000  pycnospores.     Certain  subterranean  fungi  such  as  truffles  are 


68  MYCOLOGY 

eaten  by  rodents  attracted  by  the  strong  smell  that  they  possess  and 
probably  the  mammal  is  instrumental  in  the  spread  of  the  spores. 

Many  of  the  coprophilous  fungi  have  spores  which  pass  through  the 
alimentary  canals  of  different  animals  without  being  destroyed  and 
germinating  in  the  dung,  or  manure  from  such  animals,  they  propagate 
the  species.  Pilobolns  crystallinus  is  one  of  them.  The  sporangia,  which 
are  shot  off  from  the  sporangiophore,  adhere  to  blades  of  grass,  which 
are  eaten  by  horses,  and  later  the  fungus  makes  its  appearance  on  horse 
manure.  The  spores  have  passed  through  the  horse  apparently  unaf- 
fected and  more  readily  germinable.  Man  with  his  agricultural  imple- 
ments is  concerned  with  the  spread  of  fungous  spores.  Giissow  states 
that  a  threshing  machine,  which  has  been  used  for  threshing  smutted 
wheat,  is  infested  so  fully  with  spores  that  any  grain  subsequently 
threshed,  unless  the  machine  is  sterilized  properly  after  use,  will 
become  liable  to  infection. 


CHAPTER  VIII 
ECOLOGY  OF  FUNGI 

As  fungi  are  either  saprophytes  or  parasites,  their  Kfe  history  is 
bound  up  with  the  substratum  on  which  the  saprophytes  are  found  and 
with  the  host  plant  upon  which  the  parasite  hves,  yet  there  are  many 
diverse  forms  of  saprophytic  fungi  and  the  greatest  variety  of  fungous 
parasites.  Of  special  interest  in  connection  with  the  ecology  of  fungi 
are  the  organs  by  which  various  fungi  are  tided  over  periods  of  drought, 
inclement  seasons,  or  during  the  winter's  cold.  These  organs  are 
compacted  masses  of  hyphse  of  a  rounded,  globular,  or  ellipsoidal  form 
ranging  in  size  from  those  that  are  almost  microscopic  to  those  which 
are  the  size  of  a  small  canteloupe.  These  tuber-like  masses  of  hyphae 
in  a  resting  state  are  known  as  sclerotia  (Gr.  ayXupos,  hard).  They 
are  found  in  a  great  many  fungi,  as  commonly  in  the  ergot,  Claviceps  pur- 
purea, a.nd  the  lettuce  drop,  Sclerotinia  libertiana,  which  forms  sclerotia 
that  may  reach  a  length  of  3  cm.  in  exceptional  cases.  These  sclerotia 
are  obtained  readily  in  culture  tubes  with  beerwort  agar,  or  glucose  agar, 
as  culture  media.  From  the  sclerotium  later  arises  the  stalked  fruit 
body,  or  apothecium.  Cordyceps  militaris  is  a  fungus  which  attacks 
the  larva  of  insects.  Its  mycelium  penetrates  the  insect's  body  and 
later  in  the  Isaria  form  produces  aerial  hyphas  which  cut  off  conidio- 
spores.  The  growth  of  the  mycelium  is  such  as  to  penetrate  to  all  parts 
of  the  larva  filUng  it  up  as  if  it  were  stuffed  with  cotton. 

The  mass  of  hyphae  is  converted  into  asclerotiumand  the  larval  body 
is  mummified,  but  still  retaining  its  original  external  form.  Later,  the 
next  spring,  a  stiff-stalked  stroma  arises  with  an  enlarged  extremity  in 
which  the  perithecia  with  their  asci-  and  ascospores  are  formed.  Later 
the  needle-shaped  ascospores  are  set  free  and  by  cutting  off  conidio- 
spores  reproduce  the  disease.  Cordyceps  (Torrubia)  ophioglossoides  is 
parasitic  upon  an  underground  truffle,  Elaphomyces  muricatus,  Fig. 
21).  The  stroma  is  erect,  yellow  and  club-shaped  at  the  extremity. 
Perithecia,  asci-  and  ascospores  are  borne  in  the  swollen  part  of  the 
stroma.     The  fungus  which  discharges  its  spores  above  ground  finds  the 

69 


70 


MYCOLOGY 


Fig.  21. — A  Cordyceps  tnilitaris;  B,  Cordyceps  Hugelii  on  a  caterpillar;  D,  Cordy- 
ceps  spharocephala  on  a  wasp;  E,  Cordyceps  cinerea  on  a  beetle;  F-K,  Cordyceps 
ophioglossoides,  F  on  a  deer  truffle;  G,  ascus;  H,  conidiophore;  J,  conidiospores;  K, 
germinating  spore.     See  Die  naliirlichcn  Pflanzenfamilicn  I.  i,  p.  368. 


ECOLOGY   OF   FUNGI  7 1 

underground  truffle  in  Llie  following  manner.  When  the  spores  germi- 
nate, they  give  rise  to  hyphai  which  grow  over  a  densely  cespitose,  com- 
mon moss,  Mniiim  horniim,  which  develops  a  large  number  of  feeding 
rhizoids,  that  penetrate  the  soil  to  the  depth  at  which  Elaphomyces 
grows.  The  mycelium  of  Cordyceps  not  only  covers  the  aerial  portions 
of  the  moss,  but  follows  the  rhizoids  underground  until  they  reach  the 
underground  truffle  over  which  the  moss  may  happen  to  grow.  Bot- 
anists searching  for  Elaphomyces  always  know  where  to  look  for  it  by 
the  presence  of  the  Cordyceps  hyphae,  on  the  moss  Mnium  hornum. 
There  is  a  black  beetle,  a  native  of  France^  with  a  pale,  velvety  abdo- 
men, known  as  Bulboceras  gallicus,  about  as  large  as  a  cherry  stone.  By 
rubbing  the  end  of  the  abdomen  against  the  edge  of  the  wing  cases  it 
produces  a  gentle  chirping  sound.  The  male  has  a  horn  on  his  head. 
This  insect  burrows  in  the  soil  among  the  trees  of  the  pine  forests  and  is 
nocturnal  in  its  habits.  It  descends  vertically  into  the  soil  in  search 
of  the  underground  truffle-like  fungus,  Hydnocystis  arenaria,  upon 
which  the  insect  rabassier  feeds.  The  fungous  fruit  body  is  about  the 
size  of  a  cherry  with  a  reddish  exterior  covered  with  shagreen-like  warts. 
The  beetle,  which  feeds  upon  Hydnocystis  arenaria  and  Tuher  Requenii 
one  of  the  truffles,  locates  the  fungi  by  a  subtle  sense  of  smell.  The 
human  truffle  hunter  finds  these  underground  by  the  burrows  which 
the  beetles  make  in  digging  for  their  chief  source  of  food  and  he  usually 
finds  groups  of  these  fleshy  funguses  directly  beneath  the  openings  of 
the  beetle  holes. 

Rozites  gongylophora  is  a  gill  fungus  which  is  raised  as  a  fodder  by 
leaf-cutting  ants  in  their  subterranean  passageways  in  the  tropics  of 
South  Brazil. 

On  a  visit  to  the  Berlin  Botanical  Garden  in  1898,  the  writer  noted 
the  following  remarkable  examples  of  sclerotia-bearing  fungi:  Poly- 
porus  sapurema  A.  Moller  (Fig.  92,  Teil  I,  Abt.  i**,  Die  naturlichen 
Pflanzenfamilien,  p.  171).  The  sclerotium  is  over  30  cm.  in  diameter 
and  weighs  at  least  20  kg.  It  is  furrowed  and  roughened  and  leather 
colored.  A  specimen  from  Blumenau,  Brazil,  developed  in  the  Victoria 
house  of  the  Berlin  Garden  four  large  pilei  in  August  and  September, 
1897.  Polyporus  mylittce  found  in  Australia  produces  a  sclerotium 
{Mylitta  australis  Fr.),  which  as  "native  bread"  is  used  as  food 
by  the  natives.     Polyporus  tuhcraster,  which  grows  in  the  mountains 

1  Fabre,  F.  H.:  Social  Life  in  the  Insect  World,  1912    217-237. 


72  MYCOLOGY 

of  Italy,  develops  a  large  edible  sclerotium  called  by  the  natives 
pietra  fungosa.  The  sclerotium  of  Polystictus  socer  (Fig.  94  A,  Teil  I, 
Abt.  I**,  Die  naturUchen  Pflanzenfamilien,  p.  177),  known  as 
Pachyma  malacense,  is  of  variable  shape,  8  to  10  cm.  long,  brownish  red 
externally  with  a  white  interior.  It  is  found  in  the  Malay  Archipelago. 
These  are  a  few  of  the  true  sclerotia  which  probably  includes  the 
"tuckahoe"  of  the  North  American  Indian,  Pachyma  cocos. 

Living  on  limbs,  twigs  and  the  leaves  of  the  beech  in  the  deep 
shade  of  the  forest  is  found  a  scale  insect  {Schizonema  imbricator)  ,^ 
which  is  covered  by  a  woolly  coat  consisting  largely  of  a  waxy  secretion 
from  the  body.  This  woolly  material  is  quite  abundant  and  where  the 
insects  live  in  masses  together  the  entire  limb,  or  leaf  surface  has  a 
downy  white  appearance.  The  abdomen  of  the  insect  moves  con- 
stantly with  a  jerky  motion  and  the  cottony  material  is,  therefore, 
constantly  agitated.  The  insects  secrete  a  honey  dew  so  copiously 
that  it  runs  down  to  the  leaves  beneath  and  to  the  ground.  Upon  this 
honey  dew  and  the  dead  bodies  of  the  scale  insect,  a  pyrenomycetous 
fungus,  Scorias  spongiosa,  lives.  It  grows  as  a  spongy  mycelium  con- 
sisting of  much-branched,  rigid,  septate  hyphge  with  the  strands  glued 
together  by  a  mucilage.  Pyriform  perithecia,  long-necked  spermogonia 
and  pycnidia  are  formed  from  the  mycelium,  which  is  saprophytic 
on  the  products  of  the  insect's  body. 

The  anther  smut  of  the  caryophyllaceous  flowers  occurs  in  America 
and  Europe  on  Cerastium  viscosum,  Saponaria  officinalis  and  Silene 
inflaia,  and  on  species  of  Dianthus,  Lychnis,  Melandrium,  Stellaria, 
etc.  The  spores  of  this  smut  replace  the  pollen  grains  in  the  anthers 
of  these  plants  and  when  the  flowers  open  a  violet  smut  dust  is  dis- 
charged from  the  anthers  instead  of  the  pollen.  Female  flowers  of 
Melandrium  attacked  by  the  fungus  show  a  marked  morphologic 
differentiation  in  the  development  of  mature  stamens  out  of  staminal 
rudiments.  These  anthers  are  invaded  by  the  fungus  and  in  them  the 
parasite  fructifies. 

The  formation  of  galls  is  a  marked  feature  of  the  ecology  of  fungi. 
One  form  of  these  malformations  is  seen  in  the  witches'  broom  (hexen 
besen)  which  are  due  to  the  attack  of  a  number  of  species  of  Exoascus 
on  different  forest  trees;  The  branchlets  are  clustered  into  broom-like 
masses  with  leaves  that  are  somewhat  altered  in  shape  and  fall  earlier 

^Harshberger,  J.  W.:  Joum.  of  Mycol.,  8:  160,  October,  1902. 


ECOLOGY    or    FUNGI  73 

than  those  on  normal  twigs.     Witches'  brooms  are  found  on  such  conif- 
erous trees  as  the  white  cedar  in  New  Jersey  and  are  due  to  Gymno- 


FiG.   22. — Black  knot  of  plum,  Plowrighlia  morbosa,  on  beach  plum,  Priinus  marilima 
Nantucket,  August  17,  1915. 

Sporangium  Ellisii,  a  rust  fungus.  These  malformations  occur  on  the 
hackberry,  but  on  this  tree  they  are  due  to  the  attack  of  a  mite  Phy- 
toptus  followed  by  a  fungus.     Plum  pockets  are  a  form  of  gall  in  which 


74  MYCOLOGY 

the  fruit  is  enlarged  by  the  attack  of  the  fungus  at  the  expense  of  the 
stone  which  fails  to  develop.  The  hollow  galls  on  the  plum  are  due  to 
Exoascus  pruni.  The  so-called  cedar  apples  on  our  red  cedar  trees  in 
the  spring  are  caused  by  the  attack  of  an  annual  rust  fungus,  Gym- 
nosporangium  juniper i-virgini ana,  and  from  the  surface  of  these 
apples  two-celled  spores  arise.  The  white  rust  of  cruciferous  plants, 
Cystopus  candidus,  produces  blisters  on  the  leaves  and  stems  of  shep- 
herd's purse.  The  black  knot  of  the  plum  is  a  tumor-like  swelling  of 
the  branches  of  plum  trees  due  to  the  attack  of  an  ascomycetous  fungus, 
Plowrightia  morbosa  (Fig.  22).  Large  swellings  on  oak  trees  the  size  of 
a  man's  head  and  over  are  caused  by  a  fungus,  Diachana  strumosa,  and 
some  of  these  swellings  may  be  the  size  of  a  large  pumpkin.  Galls  due 
to  insects  are  frequent  on  plants,  but  a  discussion  of  them  is  extralimital. 

According  to  conditions  of  environment,  we  may  briefly  treat  of 
fungi  as  hygrophytic,  mesophytic  and  xerophytic  forms.  The  hygro- 
phytic  forms  include  the  aquatic  fungi,  such  as  Achlya^  Mono- 
ble pilaris,  Saprolegnia  and  other  genera  which  live  and  carry  on 
their  reproduction  in  water.  Perhaps  to  this  group  would  belong 
a  fungus  of  the  genus  Cyttaria,  which  was  found  by  Darwin  in  the 
beech  (Nothofagus)  forests  of  southern  Patagonia.  The  beech  trees 
grow  in  cold,  wet  valleys  completely  barricaded  by  great  moulder- 
ing trunks  of  former  beech  trees  on  which  the  globular,  bright  yellow 
fructification  occurs  and  which  is  eaten  by  the  Fuegians. 

The  mesophytic  forms  include  many  of  the  common  fleshy  gill 
fungi  that  live  in  our  woods  and  forests,  appearing  in  surprisingly  great 
numbers  after  a  spell  of  wet  weather.  Here  we  might  include  species 
of  Amanita,  Boletus,  Russula,  and  Clavaria  and  others  which  are  not 
infrequent,  while  in  our  meadows  occur  mushroom  and  coprini.  Three 
conditions  seem  favorable  to  their  growth:  abundant  leaf  mould, 
warmth  and  abundant  moisture. 

The  habitats  of  the  fleshy  fungi  are  of  general  interest.  Collybia 
platyphylla  develops  its  fruit  bodies  on  the  shaded  side  of  decaying 
logs.  The  fairy-ring  fungus,  Marasmius  oreades  (Fig.  23)  produces  its 
sporophores  in  lawns  in  the  form  of  rings  long  known  as  fairy  rings. 
Frequently  grassy  spots  are  enclosed  by  the  circle  of  toadstools  which 
are  several  feet  in  diameter.  The  fruit  bodies  of  Pholiota  adiposa 
(Fig.  24)  grow  from  wounds  in  living  trees. 

In  forest  operations  the  slash,  when  scattered,  rots  more  rapidly 
than  when  piled.     This  is  due  to  the  fact  that  two  types  of  fungi 


ECOLOGY    OF    FUNGI  75 

are  active  in  rotting  the  brush,  one  set  entering  the  Hmbs  and  branches 
above  the  ground  and  the  other  gaining  access  to  the  brush  actually 
in  contact  with  the  soil.  Brush  is  rotted  at  the  top  when  piled 
with  one  group  of  fungi  and  at  the  bottom  by  another  group,  while 
the  middle  of  the  pile,  not  in  contact  with  the  soil  and  yet  protected 
from  the  sunlight,  apparently  will  not  rot  to  any  extent  until  the 


Fig.  23.— Fairy  ring  formed  by  Marasmius  oreades,  an  edible  toadstool.  (From 
Wiley,  Foods  and  Their  Adulteration.  After  Coville,  Circular  13,  Division  of 
Botany.' 

pile  disintegrates  suflSiciently  to  expose  these  central  layers  to  the 
soil  moisture  on  the  one  hand,  or  to  the  sunlight  on  the  other. 
Four  fungi  cause  rotting  of  oak  slash  in  Arkansas,  viz.,  Stereum 
rameale,  S.  umbrinum,  S.  versiforme  and  S.  fasciatum.  Two  fungi  are 
responsible  for  the  decay  of  short-leaf  pine  slash.  They  are  Lenzites 
sepiaria  and  Polyslictus  abiet'mus.^ 

The  xerophytic  forms  are  those  which  have  corky  or  leathery  fruit 

^Lona,  W   II.:  Investigation  of  the  Rotting  of  Slash  in  Arkansas.     U.  S.  Dept. 

Agric.  Bull.  496,  Feb.  16,  191 7;  also  Humphrey,  C.  J.:  Timber  Storage  Conditions  in 

the  Eastern  and  Southern  States  with  Reference  to  Decay  Problems  Bull,  510,  U. 

S.  Dept.  Agric,  May  17,  1917. 


76 


MYCOLOGY 


bodies  growing  on  sticks  and  logs  where  they  can  dry  up  without  any 
loss  of  vitaHty.  They  revive  after  a  rainfall  and  resume  the  function 
of  discharging  spores  and  the  discharged  spores  are  capable  of  germina- 


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Fig.  24. — Pholiola  aJiposa  growing  from  a  wound  in  a  living  tree  (edible). 
(After  Patterson,  Floraw  and  Charles,  Vera  K.,  Bzill.  175,  U.  S,  Dept.  Agric,  Apr.[2S, 
1915-) 

tion.     DcBdalea  (Fig.  202),  Polystictus  and  Stereum  are  typical  genera  of 
the  xerophy tic  log  flora.     Buller ^  describes  the  fruit  bodies  of  Schizophyl- 
lum  commune  as  possessing  special  adaptations  for  a  xerophytic  mode  of 
1  BuLLER  A.  H.  Reginald:  Researches  on  Fungi,  1909:  ^64. 


ECOLOGY   OF   FUNGI 


77 


Fig.  25. — Schizophyllum  commune,  a  xerophyte.  A  and  B,  fruit-bodies  seen 
from  above  growing  on  wood,  natural  size.  C  and  D,  two  fruit-bodies  seen  from 
below  and  in  section;  about  twice  magnified;  £,  section  through  pileus  in  wet  weather 
showing  gills  split  down  their  median  planes;  F,  section  of  a  dry  pileus;  E  and  F 
about  12  times  natural  size,  (after  Buller,  Researches  on  Fungi,  1909:  114.) 


78  MYCOLOGY 

existence  (Fig.  25).  "The  gills  are  partially  or  completely  divided 
down  their  median  planes  into  two  vertical  plates.  While  desiccation 
is  proceeding,  the  two  plates  of  each  of  the  longer  and  deeper  gills  bend 
apart  and  spread  themselves  over  the  shorter  and  shallower  gills. 
When  desiccation  is  complete,  the  whole  hymenium  is  hidden  from 
external  view  and  the  fruit  body  is  covered  both  above  and  below  with  a 
layer  of  hairs  (Fig.  25).  The  closing  up  of  the  fruit  bodies  at  the 
beginning  of  a  period  of  drought  serves  to  protect  the  hymenium.  A 
fruit  body  which  retains  its  vitality  even  when  dry  for  two  years  will 
revive  again  in  a  few  hours  and  spores  are  discharged"  (Fig.  25). 

As  it  is  not  the  purpose  of  this  book  to  consider  the  so-called  Hchens 
in  the  classification  which  follows  as  distinct  entities  in  which  the 
lichen  fungus  and  the  lichen  alga  are  in  symbiosis  forming  a 
lichen  thallus,  it  is  important  to  describe  the  ecology  of  the  actual 
relationship  of  the  two  plants  to  each  other,  as  a  matter  of  botanic 
interest.  Danilov,  Elenkin,  Peirce  and  Fink  have  shown  that  the  dual 
hypothesis,  or  that  of  mutuahstic  symbiosis,  is  untenable.  A  lichen 
is  a  fungus  belonging  to  the  orders  ASCOMYCETALES,  or  BASIDIO- 
MYCETALES,  which  lives  during  all  or  part  of  its  life  in  parasitic 
relation  with  an  algal  host  and  also  sustains  a  relation  with  an  organic 
or  an  inorganic  substratum.  Having  squarely  assumed  this  position 
as  to  the  true  nature  of  what  currently  passes  for  a  lichen,  it  is  interest- 
ing to  note  that  there  are  ten  algae  known  as  Hchen  hosts:  Chlorococcum 
(Cystococcus)  humkola,  Pahnella  botryoides,  Trentepohlia  (Chroolepus) 
umbrina,  Pleurococcus  vulgaris,  Dactylococcus  infusionmn,  Nostoc  lichen- 
oides (?),  Rivularia  nitida,  Polycoccus  pimctijormis,  Gleocapsa  polyderma- 
tica  and  Sirosiphon  pulvinatus.  It  is  important  to  note,  that  although 
the  larger  number  of  the  above  are  blue-green  algae,  yet  the  two  species 
of  green  algae.  Chlorococcum  humicola  and  Trentepohlia  umbrina  form 
the  hosts  of  many  more  lichens  than  all  the  others  combined.  Hence 
the  student  of  these  plants  can  study  the  algicolous  fungi,  mainly 
ASCOMYCETELES,  a  few  BASIDIOMYCETALES,  those  parasitic 
upon  algje,  as  the  lichens,  while  the  non-algicolous  fungi  can  be  over- 
looked by  the  lichenologists.  We  can  do  no  better  than  quote  Bruce 
Fink,^  who  sums  up  the  main  arguments  against  mutualism  and  the 

1  Fink,  Bruce:  The  Nature  and  Classification  of  Lichens.  I.  Views  and  Argu- 
ments, Mycologia,  iii:  231-269,  September,  1911;  II.  The  Lichen  and  its  Algal  Host, 
Mycologia,  iv:  97-166,  May,  1913. 


ECOLOGY    OF   FUNGI  79 

advocation  of  the  fungal  nature  of  lichens,  as  follows:  "Lichens  com- 
monly grow  where  there  are  free  algae  of  the  same  species  as  those 
parasitized  by  these  Uchens.  The  spores  of  the  lichens  germinate  and 
attack  the  free  alga;  as  other  fungi  attack  their  hosts.  Lichens  perform 
like  other  fungi  on  culture  media  and  may  be  made  to  produce  their 
reproductive  organs  on  these  media.  Lichen  spores  also  attack  the 
algal  hosts,  when  the  spores  and  the  algae  are  introduced  into  cultures 
together;  and  the  resulting  lichen  is  normal  and  sometimes  fructifies 
in  the  cultures.  Algal  hosts  extracted  from  lichen  thalli  grow  in  cul- 
tures like  free  algae  of  the  same  species  grown  on  similar  culture 
media.  The  researches  of  Elenkin  and  Danilov  prove  that  lichen 
hyphae  absorb  food  from  the  algal  host  cells,  which  are  killed  by 
severe  parasitism,  or  more  probably  by  parasitism  and  saprophytism 
combined.  The  relation  of  the  lichen  to  its  substratum  proves  that 
higher  lichens  can  take  comparatively  little  food  from  it  and  must 
depend  more  than  lower  lichens  upon  the  algal  hosts;  and  this  shows 
that  the  parasitism  of  the  lichen  upon  the  algal  host  has  become  more 
severe  in  the  evolution  of  the  higher  lichens.  Finally,  the  algae  para- 
sitized by  lichens  are  in  a  disadvantageous  position  with  reference  to 
carbon  assimilation. 

"Lichens  are  like  other  fungi  with  respect  to  vegetative  structure 
and  fruiting  bodies.  The  bridges  which  connect  lichens  with  other  fungi 
are  not  few,  but  many.  Since  it  is  thoroughly  demonstrated  that  the 
lichen  is  parasitic,  or  partly  parasitic  and  partly  saprophytic  on  the 
alga,  there  is  no  longer  even  a  poor  excuse  for  a  'consortium'  or  an 
'individualism'  hypothesis. 

"The  parasitism  of  lichens  on  algae  is  peculiar  in  that  the  unicellular 
or  the  filamentous  hosts  are  enclosed  usually  by  the  parasite,  which 
carry  more  or  less  food  to  the  host.  The  host  inside  of  the  parasite  is 
placed  in  a  disadvantageous  position  with  reference  to  carbon  assimila- 
tion and  may  depend,  for  its  carbon  supply,  more  or  less  upon  material 
brought  from  the  substratum  by  the  parasite.  Some  algal  individuals, 
not  yet  parasitized,  may  be  found  in  most  lichen  thalli." 

Lichen  thalli  are  of  three  kinds:  crustaceous,  foliose  and  fruticose. 
The  arrangement  of  the  layers  of  the  lichen  fungus  and  its  algal  host 
varies  in  different  lichens,  but  in  Stkta  the  following  are  met  in  a  ver- 
tical section  of  the  thallus  (Fig.  26) : 

(a)  Tegumentary  layer. 


8o 


MYCOLOGY 


Fig.  26. — A  foHaceous  lichen,  Parmelia  perlata.  i,  Plant  slightly  reduced  in 
size;  a,  apothecia;  b,  lobe  of  thallus;  c,  patches  of  soredia;  2,  longitudinal  section  of 
apothecium  and  cross-section  of  thallus;  a,  ascus;  b,  c,  hypothecium;  d,  upper  gonidial 
(upper  algal)  layer;  e,  medullary  layer;/,  lower  gonidial  layer;  g,  lower  cortical  layer; 
I,  3,  cross-section  of  vegetative  thallus.      (From  Gager.     After  Schneider.) 


ECOLOGY   OF   FUNGI  8l 

(b)  Upper  cortical  layer. 

(c)  Algal  layer  (gonidial  layer). 

(d)  Medullary  layer. 

(e)  Lower  cortical  layer. 

The  tegumentary  layer  consists  of  several  rows  of  flattened  hyphal 
cells  extending  at  right  angles  to  the  underlying  cortical  cells  which 
consisting  of  hyphal  cells  are  pseudoparenchymatous,  resembling  the 
parenchyma  tissue  of  higher  plants.  The  algal  layer  contains  the 
gonidia,  or  green  plants,  which  act  as  hosts  to  the  fungous  hyphge.  The 
medullary  layer  which  is  thicker  than  the  others  consists  of  much 
elongated  hyphae  forming  a  loosely  interwoven  tissue  with  large  air 
spaces.  The  lower  cortical  layer  is  pseudoparenchymatous  and  from  its 
lower  surface  rhizoids  are  developed.  The  apothecia  and  perithecia 
are  the  fruit  bodies  of  the  ascomycetous  fungi  which  form  the  lichens. 
A  vertical  section  through  an  apothecium  of  Sticta  shows  the  following 
layers:  (a)  the  epithecium,  (b)  the  thecium  consisting  of  the  spore 
sacs  (asci)  and  paraphyses,  (c)  the  hypothecium  or  hyphal  structure 
immediately  below  the  thecium,  (d)  upper  algal  layer,  (e)  medullary 
layer,  (/)  .lower  algal  layer,  (g)  cortical  layer  (Fig.  26). 

Some  of  the  fruticose  lichens  have  a  central  core-like  strand  of  hyphae 
running  through  the  medullary  region  which  serves  as  supporting 
mechanic  tissue  as  in  Usnea  barbata.  The  soredia  are  vegetative  repro- 
ductive bodies  consisting  of  from  one  to  many  algae  surrounded  by 
continuous  hyphal  tissue  and  are  common  upon  the  upper  surface  and 
margins  of  most  of  the  higher  lichen  thalli.  Among  the  Basidio- 
LiCHENES  basidia  are  formed  with  basidiospores  on  sterigmata  as  in 
Cora,  Dictyonema,  Laudatea. 


CHAPTER  IX 
FOSSIL  FUNGI  AND  GEOGRAPHIC  DISTRIBUTION 

Fungi  in  the  Fossil  State.^ — All  the  known  fossil  fungi  numbering 
over  400  species  have  been  figured  and  described  by  Meschinelli  in  his 
"Fungorum  fossilium  omnium  Iconographia "  published  in  1898. 
Zeiller  in  discussing  the  chronologic  sequence  of  the  groups  of  fungi 
states  that  representatives  of  the  families  Chytrideace^,  Mucora- 
CE^  and  Peronosporace^  have  been  found  in  the  tissues  of  the 
higher  plants  preserved  in  rocks  of  lower  Carboniferous  and  Permian 
ages.  Many  different  plants  extending  from  the  Carboniferous  period 
upward  show  various  forms  of  the  ASCOMYCETALES  on  leaves  and 
in  the  tissues  especially  those  of  the  stems.  The  fleshy  fungi  of  the 
famines  Agaricace^  and  Polyporace^  have  been  found  in  deposits 
of  tertiary  age.  Weiss  has  announced  the  discovery  of  a  mycorrhiza 
in  the  root  of  a  probable  Lycopodiaceous  plant  of  the  lower  Carbonif- 
erous strata.  Where  Polyporus  and  Lenzites  occur,  as  in  the  brown 
coals,  silicified  woods  occur  which  have  been  half  destroyed  by  their 
mycelia. 

GEOGRAPHIC  DISTRIBUTION  OF  FUNGI 

This  important  and  interesting  subject  can  be  presented  in  the  barest 
outline.  The  modern  teaching  of  geography  emphasizes  home  geog- 
raphy as  a  fundamental  study.  In  following  this  suggestion  in  the 
investigation  of  the  local  fungi,  it  will  be  found  that  we  must  deal 
with  distinct  habitats,  such  as  leaf  mold,  sandy  soil,  wet  soil,  decayed 
logs,  tree  stumps,  living  trees,  living  herbs  and  the  like.  The  black 
mould,  Rhizopus  nigricans,  is  one  of  the  commonest  of  fungi.  It  occurs 
on  bread  and  other  organic  substrata,  such  as  sweet  potatoes,  whenever 
the  conditions  are  suitable  for  its  growth.  If  horse  manure  is  covered 
with  a  bell  jar  with  wet  paper  inside,  there  develops  first  the  gray 
mould,  Mucor  mucedo.     This  is  accompanied  or  followed  by  Pilobolus 

^Seward,  A.  C:  Fossil  Plants,  1898:  207-222. 

Weiss,  F.  E.:  A  Mycorrhiza  from  the  Lower  Coal  Measures.  Annals  of  Botany, 
xviii:  255  with  2  plates. 

82 


FOSSIL   FUNGI   AND    GEOGRAPHIC   DISTRIBUTION  83 

crystalliniis,  and  this  in  turn  by  the  white  flecks  of  Oospora  scabies. 
Coprinus  stcrcoraritis  usually  completes  this  series  of  coprophilous 
fungi  generally  found  on  horse  dung.  Sometimes  the  Mucor  is  para- 
sitized by  Piplocepkalis  and  sometimes  by  Chatocladium.  Peziza 
coccinea  is  attached  to  dead  twigs  buried  in  the  forest  leaf  mould,  and 
as  it  rises  to  the  surface,  it  develops  a  long  stipe  with  a  crimson-red 
saucer-shaped  apothecium  at  its  extremity.  Russula  emetica,  R. 
virescens,  species  of  Clavaria  and  Boletus  are  regularly  found  beneath 
deciduous  trees  growing  out  of  the  forest  litter.  The  pufifball,  Sclero- 
derma vulgare,  is  found  on  the  tops  of  old  stumps  in  gregarious  clusters. 
Polyporus  sulphur  ens  grows  out  of  partly  dead  chestnut  and  oak  trunks; 
while  the  hymenophores  of  Armillaria  mellea  are  found  clustered  about 
the  bases  of  trees  beneath  the  bark  of  which  the  rhizomorphs  will  be 
found  growing.  A  species  of  Hydnmn  was  found  a  few  feet  above  the 
ground  on  a  beech  tree  and  Fistulina  hepalica  attached  to  tree  trunks, 
where  the  swollen  base  gradually  blends  with  the  straighter  hole  above. 
Amanita  muscaria  and  A.  phalloides  grow  in  solitary  splendor  at  the 
edges  of  woods  and  copses,  while  the  habitat  of  the  mushroom  in  open 
fields  is  quite  distinctive. 

The  earth-star,  Geaster  hygrometricus,  grows  more  frequently  in 
sandy  soil,  where  it  spreads  out  its  peridial  segments. 

The  habitat  of  the  local  species  of  the  lichen  fungi  is  of  interest. 
The  brown-fruited  cup  cladonia,  Cladonia  pyxidata,  grows  on  stumps 
and  on  the  earth,  while  the  scarlet-crested  cladonia,  Cladonia  cristatella, 
is  found  on  dead  wood.  The  Iceland  moss,  Cetraria  islandica,  grows 
on  the  ground  as  also  the  reindeer-lichen,  Cladonia  rangiferina,  in  ex- 
tensive masses.  Another  earth-inhabiting  form  is  Peltigera  canina. 
The  trunks  of  trees  are  marked  by  the  presence  of  Parmelia  perlata 
and  the  fruticose  bearded  lichen,  Usnea  barhata.  Smooth  bark  appears 
covered  with  runic  character  traced  by  the  fruit  bodies  of  Graphis 
scripta.  The  rock-dwelling  lichens  include  Physcia  parietina  and  the 
rock  tripe  (tripe  de  roche),  Umbilicaria  which  grows  on  the  outcrops 
of  Octorara  schists  at  the  Gulph. 

The  distribution  of  the  chestnut  blight  fungus,  Endothia  parasitica, 
is  of  more  than  local  interest,  although  the  agitation  to  control  it 
started  near  Philadelphia.  Apparently  the  fungus  was  introduced  from 
China,  where  it  has  been  found  recently,  with  nursery  stock  into  Long 
Island.     From  the  neighborhood  of  New  York  City,  it  spread  northeast, 


84 


MYCOLOGY 


northwest,  west  and  southwest.^  Now  it  is  found  in  Connecticut, 
New  York,  throughout  New  Jersey,  and  as  far  west  as  the  Alleghany 
mountains  in  Pennsylvania.  In  isolated  areas,  it  occurs  in  Virginia 
and  West  Virginia,  endangering  the  future  of  the  chestnut  tree  in 
America  (Fig.  27). 

Wherever  the  cultivation  of  the  higher  plants  extends,  the  fungi 
pecuUar  to  these  plants  will  be  found,  as  the  wheat  rust,  Puccinia 


Fig.  27. —  Map  of  the  eastern  United  States  showing  distribution  of  chestnut 
blight  disease  in  ipii.  Horizontal  lines  indicate  area  with  approximately  all  the 
trees  dead;  vertical  lines  approximate  area  where  infection  is  complete;  dots  indicate 
advanced  points  of  infection.      {From  Gager,  after  Metcalf,  U.  S.  Farmers'  Bull.  467.) 


graminis,  in  Europe,  America  and  Australia.  The  damping-off  fungus^ 
Pythium  de  Baryanum,  which  is  death  to  seedlings,  has  been  studied  by 
German,  English  and  American  botanists,  as  a  reference  to  the  litera- 
ture will  show.  The  downy  mildew,  of  the  grape,  Plasmopara  viticola, 
apparently  of  eastern  American  origin,  is  found  now  in,  Europe  and 
Cahfornia,  where  it  has  become  a  serious  pest. 

The  black  knot,  Plowrightia  morbosa,  was  apparently  at  one  time 
confined  largely  to  the  Atlantic  seaboard  and  was  particularly  abundant 
in  New  England  and  New  York.     It  has  now  spread  across  the  northern 

'  Cf.  Stevens,  Neil  E.:  Some  Factors  influencing  the  Prevalence  of  Endothia 
gyrosa.      Bull.  Torr.  Bot.  flub,  44  :  127-144.   March,  191 7. 


FOSSIL    FUNGI   AND    GEOGKAPHIC    DISTRIBUTION  85 

United  States  to  the  Pacific  coast.  Such  diseases  as  the  sooty  mold  of 
orange,  Meliola  camellicB,  and  the  brown  rot  of  the  lemon,  Pythiacystis 
citriophthora,  arc  confined  to  these  last  plants  and  to  the  regions  where 
the  citrus  fruits  grow.  The  anthracnose  of  the  sycamore,  Gnomonia 
veneta,  is  parasitic  upon  the  leaves  and  shoots  of  the  sycamore  or  plane 
tree,  Platanus  occidentalism  causing  its  leaves  to  dry  up,  as  if  bitten  by 
early  frosts.  It  seems  to  be  more  prevalent  in  the  bottom  of  valleys, 
where  the  plane  tree  grows  along  streams,  as  here  we  find  cold-air 
drainage.  Sometimes  after  the  first  crop  of  leaves  is  lost,  a  second 
crop  appears.  Wherever  the  sycamore  grows,  Gnomonia  may  be  ex- 
pected. The  so-called  fly-cholera  fungus,  Empusa  muscce,  is  parasitic 
in  flies  and  is  present  on  these  insects  in  Europe,  even  in  the  far  north, 
in  North  America  and  South  America  (Argentina).  The  coprophilous 
fungus,  Basidioboliis  ranarum  occurs  on  the  dung  of  frogs  in  Europe 
and  America.  Taphrina  ccsrulescens  does  not  seem  to  be  choice  about 
its  hosts,  occurring  as  spots  on  the  leaves  of  Quercus  cerris,  puhescens, 
sessiliflora  in  middle  and  southern  Europe  and  on  Quercus  alba,  aquatica, 
coccinea,  laurifolia,  rubra,  velutina  in  North  America.  The  hairy 
earth-tongue,  Geoglossmn  hirsutum,  is  truly  cosmopoHtan,  as  it  has  been 
reported  from  all  over  Europd,  North  America,  Java,  Mauritius  and 
Australia.  The  genus  Cyttaria  with  eight  ascospores  in  each  ascus  in- 
cludes six  species.  C.  Darwinii  and  C.  Berterii  were  discovered  by 
Darwin  in  Patagonia.  C.  Gunnii  occurs  in  Tasmania  and  C.  Harioti  in 
Terra  del  Fuego.  None  of  the  species,  therefore,  are  found  outside  of 
the  southern  hemisphere  (Fig.  28).  The  genus  Hypomyces  includes 
species  which  live  parasitically,  or  saprophytically,  on  other  fleshy 
fungi.  H.  ochraceus  lives  on  species  of  Russula  in  Germany,  England 
and  North  America;  H.  chrysospermus  occurs  on  species  of  Boletus  in 
Europe;  H.  aurantius  on  Polyporace^  and  Thelephorace^  in 
Europe;  H.  lateritius  on  Lactarius  in  Europe  and  North  America;  H. 
vlolaceus  with  its  tender  small  stroma  and  violet-colored  fruit  body  lives 
on  a  slime  mould  Fuligo  septica  in  northern  Europe;  H.  viridis  is  found 
on  species  of  Lactarius  and  Russula  in  northern  Europe  and  North 
America;  //.  cervinus  grows  on  Helvellace^  and  large  Pezizace^  in 
Europe;  H.  fulgens  appears  on  the  bark  of  pine  trees  in  Finland  and 
Sweden;  H.  Stuhlmanni  is  confined  to  Poly  poms  bukabensis  in  Central 
Africa;  H.  chrysostomiis  is  reported  from  Ceylon  and  H.  flavescens  on 
a  Polyporus  in  North  America.     Hypomyces  lactijluorum  planes  down 


86  MYCOLOGY 

the  gill  surfaces  of  the  Lactarius  sp.  on  which  it  grows,  converting  an 
otherwise  grayish-white  fruit  body  into  a  cinnabar-red  one.  It  is 
found  in  the  woods  about  Philadelphia,  Pa.  The  fungi  belonging  to 
the  family  Laboulbeniace^  are  included  in  28  genera  and  approxi- 
mately 152  species,  and  have  been  made  known  largely  through  the 
studies  of  Prof.  Roland  Thaxter  of  Harvard  University.  A  few  species 
are  found  in  Europe,  in  the  tropics  of  Africa,  America  and  Asia,  but 
North  America  is  extraordinarily  rich  in  specific  forms.  They  occur 
on  dipterous,  neuropterous  and  coleopterous  insects,  especially  those 
which  live  in  damp  places  or  in  the  water.  The  corn-smut  Ustilago 
maydis  is  a  parasite  confined  exclusively  to  the  maize  plant,  Zea  mays, 
and  to  the  closely  related  if  not  identically  the  same  grass  the  teosinte; 
EuchlcBna  mexicana  as  pointed  out  some  years  ago  by  the  writer^  as 
proof  of  the  common  origin  of  these  two  grasses.  Wherever  maize  is 
cultivated  the  smut  is  found  associated  with  it. 

The  rusts  (Uredine^)  are  arnong  the  most  specialized  of  fungi  in 
their  parasitic  habits,  some  species  being  confined  to  one  or  two  hosts. 
They  ascend  with  their  host  plants  above  the  snow  line  on  high  moun- 
tains and  toward  the  poles  wherever  flowering  plants  and  ferns  grow. 
Whole  genera  are  confined,  however,  to  certain  regions.  Thus  the 
genus  Ravenelia  which  lives  on  mimosaceous  and  caesalpinaceous  plants 
extends  north  to  the  40°  north  latitude.  Many  rust  fungi  are  iden- 
tically the  same  in  North  America,  north  and  middle  Europe,  and  of 
the  500  species  known  from  North  America  and  400  European  rusts 
approximately  150  species  are  common  to  both  countries.  Only  a  few 
Mediterranean  species  are  found  in  North  America,  as  Uromyces  gly- 
cyrrhizcB  and  Puccinia  Mesneriana.  A  less  number  of  species  are  com- 
mon to  North  and  South  America.  It  is  noteworthy  that  Puccinia 
malvacearum  introduced  into  Spain  from  Chile  in  1869  has  in  the  forty- 
six  years  which  have  elapsed  since  its  introduction  into  Europe  spread 
over  the  world. 

The  genus  Exohasidium  includes  18  species  of  fungi  which  cause  the 
formation  of  fleshy  galls  chiefly  on  plants  of  the  family  Ericace^. 
Tabulated  the  principal  species  are: 

Exobasidkim  laccinii  on  Vaccinium;  Europe,  Siberia,  America. 
Exohasidium  rhododendri  on  Rhododendron,  Europe,  America. 
1  Harshberger   J.  W.:  Cont.  Bot.  Lab.  Univ.  of  Pa.,  1901:  234. 


FOSSIL    FLTNGI   AND    GEOGRAPHIC   DISTRIBUTION  87 

Exohasidiiivi  Icdi  on  Ledum,  Finland. 

Exobasidium  andromcdcc  on  Andromeda,  Europe,  North  America. 

Exobasidimn  azalew  on  Azalea,  North  America. 

Exobasidium  anlarclicum  on  Lcbetanlhus,  Patagonia. 

Exobasidium  gaylussacice  on  Gaylussaeia,  Brazil. 

Exobasidium  leucothoes  on  Leucolho'e,  Brazil. 

Exobasidium  lauri  on  Laurus,  Italy,  Portugal,  Canaries. 

Exobasidium  Warmingii  on  Saxifraga  aizoon,  Greenland,  Tyrol,  North  Italy. 

In  closing  this  consideration  of  the  geographic  distribution  of  the 
fungi,  the  interest  which  attaches  to  it  as  a  study  may  be  best  empha- 
sized by  giving  in  tabular  form  the  distribution  of  the  species  belonging 
to  a  single  family.  The  family  Clathrace^e  includes  eleven  genera  of 
highly  specialized  morphology. 

Family  Clathrace^. 

1.  Clathrus   cancellatiis ,    Mediterranean    Region,    South    England, 
North  America. 

Clathrus  columnatus,  North  and  South  America. 

2.  Blunienavia  rhacodes,  Brazil. 

3.  Ileodidyon  cibarium,  Australia,  New  Zealand,  South  America. 

4.  Clathrella  chrysomycelina,  Tropic  South  America. 
Clathrella  pusilla,  Australia,  New  Caledonia. 
Clathrella  kamerunensis ,  Cameroon. 
Clathrella  Preiissii,  Cameroon. 

Clathrella  crispa,  Central  and  Tropic  South  America. 

5.  Simhliim  periphragmoides,  Tonkin,  Java,  Ceylon,  East   Indies, 
Mauritius. 

Simblum  sphcerocephalum,  North  and  South  America. 

6.  Colus  Miilleri,  Australia. 

Colus  hirudinosus,  Mediterranean  Region. 
Colus  GarcicB,  Tropic  South  America. 
Colus  Gardncri,  Ceylon. 

7.  Lysurus  mokusin,  China. 

8.  Anthurus  borealis,  North  America. 
Anthurus  Clarazianus,  Argentina. 
Anthurus  Woodii,  Natal. 
Anthurus  Mullerianus,  Australia. 
Anthurus  cruciatus,  Tropic  South  America. 


88  MYCOLOGY 

9.  Aseroe  rubra,  New  Zealand,  Australia,  Java,  Ceylon,  Tonkin, 

South  America. 
10.  Calathiscus  sepia,  East  Indies. 

Calathiscus  Puiggarii,  South  Brazil. 
II    Kalchbrennera    corallocephala,    Africa,     Cape,    Natal,    Angola, 

Cameroon,  Zambezi  Region. 


CHAPTER  X 
PHYLOGENY  OF  THE  FUNGI 

One  of  the  most  consistent  attempts  at  representing  the  phylogeny 
of  the  fungi  has  been  made  by  Dr.  O.  Brefeld  through  his  researches 
which  were  pubHshed  in  collected  form  in  "  Untersuchungen  aus  dem 
Gesammtgebiet  der  Mykologie. "  As  these  volumes  are  bulky  ones,  a 
student  of  Brefeld,  Dr.  F.  von  Tavel,  has  given  a  useful  summary  of 
the  chief  points  in  his  teacher's  system  in  a  book  pubhshed  in  1892, 
entitled  "  Vergleichende  Morphologie  der  Pilze."  The  phylogeny  of  the 
higher  fungi,  according  to  Brefeld,  is  based  on  the  assumption,  that 
there  is  an  entire  absence  of  sexual  organs  in  all  of  those  groups  above 
the  PHYCOMYCETES,  but  this  view  has  been  rendered  untenable 
owing  to  the  discovery  of  undoubted  sexual  organs  among  the  ASCOMY- 
CETALES  and  the  discovery  of  nuclear  fusions  in  some  of  the  rusts, 
suggesting  a  sexual  condition.  However  this  may  be,  Brefeld  and  von 
Tavel  hold  that  the  PHYCOMYCETES  are  algal-like  fungi  and  prob- 
ably derived  from  algal  ancestors. 

The  OOMYCETALES  are  not  linked  directly  with  any  of  the  higher 
fungi,  but  the  ZYGOMYCETALES  through  the  former  with  sporangia 
and  conidia  have  probably  given  rise  to  the  HEMIASCI  and  directly 
through  them  to  the  ASCOMYCETALES.  The  forms  of  ZYGOMY- 
CETALES with  conidia  above  are  phylogenetically  connected  in  the 
Brefeldian  system  though  the  HEMIBASIDII  with  the  BASIDIO- 
MYCETALES.  This  in  brief  is  an  outline  of  the  phylogenetic  views 
of  Brefeld,  as  expressed  in  a  useful  ground  plan  of  the  natural  system 
of  hyphal  fungi  by  von  Tavel. 

The  question  is  asked  naturally,  whether  the  origin  of  the  fungi  has 
been  monophyletic,  that  is  from  a  single  ancestral  form,  or  polyphyletic, 
from  a  number  of  distinct  ancestors?  This  question  can  be  answered 
only  after  an  examination  of  the  evidence.  There  are  two  orders  of  the 
PHYCOMYCETES,  or  algal  fungi,  namely,  ZYGOMYCETALES  and 
OOMYCETALES.  As  to  the  origin  of  these  forms,  the  monophyletic 
view  would  have  us  derive  the  ZYGOMYCETALES  from  the  OOMY- 


go  MYCOLOGY 

CETALES,  which  have  been  derived  in  all  probabiUty  from  an  alga 
like  Vaucheria  with  oogonia  and  antheridia,  where  the  male  sexual 
organs  are  smaller  than  the  female.  To  derive  the  ZYGOMYCE- 
TALES  from  such  a  group  would  necessitate  that  the  sexual  organs 
become  of  equal  size. 

Entomophthora  is  a  connecting  form  where  the  sexual  organs  ap- 
proach each  other  in  size.  This  genus  is  then  connected  by  insensible 
differences  with  the  heterogamic  hermaphroditic  moulds  where  there  is 
an  appreciable  difference  in  the  size  of  the  two  cells  that  conjugate,  the 
larger  being  the  female,  the  smaller  the  male,  as  in  Absidia  spinosa  and 
Zygorhynchus  heterogamus.  These  are  directly  connected  with  the 
homogamic  hermophrodite  moulds  and  these  with  the  homogamic 
heterothallic  forms.  The  polyphyletic  -view  necessitates  the  deriva- 
tion of  the  OOMYCETALES  from  a  Vaucheria-like  ancestor,  and  the 
ZYGOMYCETALES  from  a  Zygnema-like  ancestor,  where  conjugation 
of  similar  cells  (gametes)  is  found.  The  polyphyletic  origin  of  the 
fungi  is  emphasized  by  the  adherents  to  the  doctrine  of  the  origin  of  the 
AscoMYCETALES  from  red  alg£e,  as  there  are  three  points  of  contact: 
first,  sac  fungi  with  highly  developed  trichogyne  (sterilized  archicarp)  of 
the  Collema  type  with  red  algae-like  certain  existing  forms;  second,  sac 
fungi  with  highly  developed  trichogyne  of  the  Poly  stigma  type;  third, 
sac  fungi  with  simple  generalized  copulating  gametes  of  the  Gymnoascus 
type.  We  are,  however,  not  in  the  position  to  name  any  known  red 
alga  as  the  progenitor  of  the  sac  fungi,  and  it  is  far  more  reasonable  to 
search  for  one  in  another  fungous  line,  where,  in  the  hght  of  present-day 
knowledge,  there  are  known  forms  with  sexual  organs  very  much  like  the 
sexual  organs  of  simple,  known  forms  of  the  Ascomycetales.  We  are 
not  now  in  a  position  to  name  any  known  phycomycete  as  a  probable 
ancestor,  though  the  likehhood  is  that  the  original  stock  possessed  phy- 
comycetous  characters,  thus  attributing  a  monophyletic  origin  to  them. 
One  of  the  most  instructive  forms  suggesting  a  mode  of  transition  from 
the  PHYCOMYCETES  to  the  ASCOMYCETALES,  is  Dipodascus. 
Its  sexual  organs  are  strikingly  like  those  of  certain  MucorAce^  or 
Peronosporace^  in  their  young  stages.  The  sexual  organs  can  be 
recognized  as  antheridium  and  oogonium  either  from  tlie  same  thread 
(homothaUic)  or  from  different  threads  (heterothallic).  After  absorption 
of  the  wall  between  the  gametes,  the  fertilized  oogonium  (or  zygote) 
grows  out  into  an  elongate  stout  ascus,  or  zygogametangium  with  the 


PHYLOGENY    OF    THE    FUNGI  91 

production  of  numerous  spores.^  Eremascus  also  represents  such  a  con- 
necting form.  From  Eremascus  by  reduction  forms  like  Endomyces 
arose  which  in  two  diverging  series  connects  various  ascomycetous 
fungal  forms.  One  series  shows  sprout  conidia,  the  other  oidia.  The 
yeast  series,  the  Exoascus  series  are  thus  connected.  Some  would  have 
us  derive  the  Laboulbeniace^  from  red  algal  ancestors,  but  another 
opposing  view  is  that  these  unusual  fungi  have  had  a  Monascus-like 
ancestor.  The  other  branch  leads  to  the  Basidiomycetales  where  the  most 
primitive  forms  have  not  typical  basidia,  as  in  the  Hemibasidii,  and 
which  are  connected  with  such  primitive  types  as  are  included  in  the 
family.  Entomophthorace^.^  The  differentiation  of  types  within 
these  large  phyla  will  be  dealt  with  as  we  proceed  with  a  discussion  of 
the  various  groups  of  PHYCOMYCETES  and  MYCOMYCETES. 

1  Atkinson,  Geo.  F.:  Phylogeny  and  Relationships  in  the  Ascomycetes.     Annals 
Missouri  Botanical  Garden,  II:  315-376. 

2  C/.  Engler   und   Peantl;   Die    natiirlichen  Pflanzenfamilien,   I   Teil   Abt.: 
60-63. 

Masses,  George:  A  Text-book  of  Fungi,  1906:  182-195. 


CHAPTER  XI 

MOULD  FUNGI 

SUBCLASS  PHYCOMYCETES 

The  fungi  of  this  subclass  are  distinguished  by  their  siphon-like 
hyphge,  because  these  hyphae  are  unicellular  and  multinucleate  and  sug- 
gest the  algae  of  the  family  Siphonace^  to  which  Vaucheria  belongs. 
Hence  the  fungi  of  the  subclass  PHYCOMYCETES  {4>vkos,  seaweed  + 
livKTis,  a  fungus)  are  usually  designated  as  algal  fungi.  Although  the 
absence  of  transverse  septa  in  the  hyphae  is  used  as  a  fundamental  char- 
acteristic, yet  in  the  formation  of  the  reproductive  organs  transverse 
walls  or  septa  cut  these  organs  off  from  the  rest  of  the  vegetative 
mycelium.  Transverse  septa  are  found  regularly  in  some  of  the  genera, 
such  as  Dimargaris,  Dispira,  Protomyces  and  Mucor,  so  that  the  general 
statement  above  is  modified  by  such  exceptions.  A  fungus,  Leptomitus 
lacteus,  found  in  ditches  and  rivers  shows  a  characteristic  segmentation 
of  the  hyphae,  where  through  the  deposit  of  a  substance  known  as  cellu- 
lin  the  lumen  of  the  hyphae  is  nearly  closed,  but  at  the  point  of  constric- 
tion, a  small  pore  remains  through  which  the  protoplasm  passes.^ 

There  are  genera  of  the  family  Chytridiace^,  such  as  Reessia  and 
Rozella  in  which  the  protoplasm  during  the  vegetative  state  is  not  sur- 
rounded by  a  cell  wall,  but  is  naked,  and  amoeboid  in  the  host  cells. 
The  fungi  of  this  subclass  are  saprophytic  or  parasitic,  aquatic,  or 
aerial,  living  endophytically  as  a  rule.  A  few  are  parasitic  on  insects 
and  fishes.  Two  orders  are  distinguished,  viz.,  the  ZYGOMYCET- 
ALES  and  the  OOMYCETALES. 

ORDER  ZYGOMYCETALES 

The  fungi  of  this  order  show  a  strongly  developed  mycelium  con- 
sisting usually  of  unicellular,  sometimes  pluricellular,  multinucleate 
hyphas.  These  hyphae  are  distinguished  in  the  typic  forms  as  the  rhiz- 
oidal  hyphae,  aerial  hyphae  and  reproductive  hyphae.     Vegetative  re- 

1  Massee,  George:  Text-book  of  Fungi,  1906:  242. 
92 


MOULD   FUNGI  93 

production  is  never  through  motile  zoospores,  but  through  immotile 
spores  produced  in  sporangia  borne  at  the  tips  of  the  reproductive 
hyphae  known  as  sporangiophores,  or  by  means  of  conidiospores, 
chlamydospores  (Mucor  racemosus),  oidiospores,  or  gemmae.  Sexual 
reproduction  is  by  the  conjugation  of  two  similar  or  sHghtly  dissimilar 
gametes,  and  the  formation  of  a  resting  cell,  or  sexually  produced  spore, 
known  as  the  zygote,  or  zygospore.  Brefeld  beheved  that  this  group 
gave  rise  to  the  higher  groups  of  fungi  and  he  showed  an  interesting 
series  of  transition  forms  from  those  like  Mucor  with  a  typic  terminal 
sporangium  (Fig.  13)  with  numerous  sporangiospores  (endospores) 
through  Thamnidium  elegans  with  a  large  terminal  sporangium  (mega- 
sporangium)  and  secondary  lateral  smaller  sporangia  (sporangioles, 
microsporangia)  and  Thamnidium  chcetocladioides  (Fig.  32),  where  the 
absent  terminal  megasporangium  is  represented  by  a  spine-like  sporangi- 
phore,  to  Chcetodadium,  where  the  number  of  endospores  in  the  spor- 
angioles is  reduced  to  one  inclosed  within  the  sporangium,  which  be- 
haves as  a  conidiospore;  thence  to  Piptocephalis,  where  the  monosporous 
sporangiole  has  become  virtually  a  conidium,  or  conidiospore.  He  re- 
garded the  ascus  as  potentially  a  sporangium,  but  recent  discoveries 
have  shown  this  hypothetic  view  to  be  untenable,  so  that  his  views  as 
to  the  origin  of  the  ASCOMYCETALES  and  the  BASIDIOMYCE- 
TALES  from  the  ZYGOMYCETALES  must  be  considered  as  not  satis- 
factorily proved. 

Blakeslee,  who  has  studied  the  sexual  reproduction  in  the  moulds, 
finds  that  they  may  be  divided  into  two  groups,  the  homothallic  (mon- 
oecious) and  the  heterothallic  (dioecious)  forms.  The  homothallic 
moulds  are  those  in  which  the  sexual  gametes,  which  conjugate,  arise 
from  the  same  mycelium,  while  the  heterothallic  forms  are  those  in 
which  two  distinct  mycelia  contribute  the  gametes  which  ultimately 
unite  sexually.  The  homothallic  (hermaphroditic)  moulds  he  divides 
into  the  heterogamic  hermaphrodites  in  which  there  is  an  inequahty  in 
the  size  of  the  gametes  (the  large  one  being  female  and  the  small  one 
male),  and  the  homogamic  hermaphrodites  in  which  the  gametes  are  of 
equal  size.  The  heterogamic  hermaphrodites  include  the  following 
fungi :  Syncephalis,  Dicranophora  fulva,  A  bsidia  spinosa,  Zygorhynchus 
heterogamiis,  Z.  Mcelleri,  Z.  Vuillemini.  The  homogamic  hermaph- 
rodites comprise:  Mortierella  polycephala,  Mucor  genevensis,  Spinel! us 
fusiger  and  Sporodinia  grandis   (Fig.  28).     The  dioecious,  or  hetero- 


94 


MYCOLOGY 


thallic  species  are  all  homogamic,  that  is,  there  is  no  difference  in  the 
size  of  the  two  gametes  which  conjugate.     This  group  includes  such 


Fig.   28. — Zygospore  formation  in  Sporodinia  grandis  from  material  growing  on  toad- 
stool.    {Slide  prepared  by  H.  H.  York,  Cold  Spring  Harbor,  July  29,  1915.) 


)H=*^/ 


\=9c>i 


^^ij=f      /' 


Fig.  29. — Conjugation  and  development  of  zygospores  between    +  and    —  races  of 
black  mould,  Rhizopus  nigricans. 


fungi  as  Absidia  ccerulea,  Mucor  mucedo,  and  five  other  forms  of  Mucor, 
Phycomyces  nitens  and  Rhizopus  nigricans  (Fig.  29).     Taking  the  con- 


MOULD   FUNGI  95 

jugation  in  Mucor  mucedo  as  an  illustration  of  the  method,  we  find  that 
the  hyphae  of  two  distinct  mycelia,  which  may  be  designated  as  the 
+  and  —  strains,  give  rise  to  lateral  club-shaped  branches.  The  tips 
of  these  two  branches  (progametes)  come  into  contact  and  a  terminal 
cell  (gamete)  is  cut  oflF  from  each  branch  respectively  by  a  transverse 
wall.  The  double  partition  wall  is  dissolved  away  by  an  enzyme,  and 
the  two  cells  coalesce,  their  nuclei  uniting  in  pairs.  A  zygospore,  is 
formed,  as  a  resting  spore  (Figs.  28,  30  and  2,i)-  It  becomes  covered 
with  a  thick,  warty  brown  coat.  The  zygote  (zygospore)  germinates 
after  a  period  of  rest  producing  at  once,  because  of  the  concentrated 
foods  it  contains,  a  sporangiophore  bearing  a  terminal  sporangium  with 
sporangiospores.  Sometimes  the  gametes  fail  to  unite  through  some 
check  to  the  normal  conjugation  and  the  two  gametes  may  then  round 
off  and  form  thick- walled  azygospores,  and  the  size  of  these  azygospores 
depends  upon  the  size  of  the  gametes  from  which  they  develop.  Blakes- 
lee  has  discovered  that  for  the  production  of  zygospores  in  heterothallic 
moulds  the  contact  of  the  hyphae  of  two  distinct  mycelia  designated 
+  and  —  are  essential.  If  two  —  races  or  two  -|-  races  meet,  there 
is  no  result.  In  the  homothallic  moulds,  the  two  conjugating  gametes 
may  arise  from  the  same  mycelium.  Where  the  -f-  race  of  one  species 
of  mould  meets  the  —  race  of  another  species  imperfect  "hybrids"  are 
formed.  The  testing  out,  maleness  or  femaleness,  of  the  different  races 
is  made  possible  by  growing  in  proximity  different  kinds  of  moulds, 
where  a  reaction  occurs  and  imperfect  hybrids  are  formed  one  race 
must  be  plus  and  the  other  minus.  Where  the  hermaphrodite  forms  are 
grown,  it  is  noticed  that  one  gamete  is  larger  and  the  other  smaller,  and 
it  is  assumed,  that  the  larger  gamete  is  female  and  the  smaller  one  male. 
The  race  of  dioecious  Mucors,  designated  tentatively  (+),  shows  a 
sexual  reaction  with  the  smaller  or  male  gamete,  while  the  (  — )  or 
vegetatively  less  vigorous  race  shows  a  reaction  with  the  larger  or 
female  gamete.  It  is  inferred  that  the  -f  race  of  dioecious  mucors  is 
female  and  the  —  race,  male. 

The  immediate  stimulus  to  the  formation  of  the  progametes  prob- 
ably lies  in  the  contact  of  hyphae  from  different  strains  through  the 
osmotic  activity  of  the  hyphal  contents.  For  this  reason  progametes 
fail  to  form  in  relatively  dry  air.  By  suspending  two  small  bags  filled 
with  bread  soaked  in  dilute  orange  juice  and  inoculated  with  mould 
spores,  any  influence  which  the  substratum  might  show  is  eliminated. 


96  MYCOLOGY 

Zygospores  were  formed  in  one  week  where  the  aerial  radiating  hyphae 
had  come  into  contact.  By  this  experiment  all  influences  exerted 
through  the  solid  culture  media,  or  which  were  due  to  contact  of  vege- 
tative mycelia,  were  eliminated. 

The  sporangia  of  Mucor  mucedo  are  raised  upon  the  ends  of  sporangio- 
phores.  When  fully  formed  the  sporangium  consists  of  a  wall  beset 
with  spicules  of  calcium  oxalate,  the  spores  separated  from  each  other 
by  a  slimy  intersporal  substance  (zwischensubstanz),  and  a  columella 
which  projects  into  the  interior  of  the  sporangium.  The  formation  of 
spores  in  Rhizopus  nigricans  and  Phycomyces  nitens  has  been  studied  by 
Swingle,^  who  finds  that  the  columella  is  formed  by  the  cutting  upward 
of  a  circular  surface  furrow  or  cleft,  thus  cleaving  out  the  columella  over 
the  end  of  which  a  plasma  membrane  is  formed.  The  spore  plasm  of 
Rhizopus  divides  into  spores  by  furrows  pushing  progressively  inward 
from  the  surface  and  outward  from  the  columella  cleft  both  systems 
branching,  curving  and  intersecting  to  form  multinucleated  bits  of  pro- 
toplasm (the  spores)  surrounded  only  by  plasma  membranes,  which 
become  the  spore  walls  and  separated  by  spaces  filled  with  the  inter- 
sporal substance  (zwischen  substanz).  The  endospores,  or  sporangio- 
spores,  of  Rhizopus  nigricans  and  Sporodinia  grandis  are  multinucleate, 
while  those  of  Pilobolus  are  binucleate,  according  to  Harper.  The  es- 
cape of  the  mature  sporangiospores  takes  place  when  a  portion  of  the 
sporangial  wall  is  dissolved.  The  spores  escape  imbedded  in  the  inter- 
sporal slime,  which  dries  up  liberating  the  spores.  Certain  species  of 
Mucor  are  capable  of  fermenting  grape  juice,  the  power  of  fermentation 
depending  on  the  species.  The  following  species  produce  alcoholic  fer- 
mentation (Lindner) : 

Quantity  of  alcohol 
Species  by  volume, 

per  cent. 

Mucor  Jansscni 3.41 

Mucor  lamprosporus 3.71 

Mucor  javanicus 2 .  83 

Mucor  phimbeus 4.62 

Mucor  pirelloides i  •  06 

Mucor  racemosus 462 

Mucor  Rotixianus 5.25 

Mucor  griseo-cyanus 4 .  00 

Mucor  genevcnsis 5-2i 

'Swingle,  DeanB.:  Formation  of  the  Spores  in  the  Sporangia  of  Rhizopus 

nigricans  and  of  Phycomyces  nitens.     Bull,  jy,  Bureau  of  Plant  Industry,  1903. 


MOULD   FUNGI  97 

Key  to  Families  or  the  Order  Zygomycetales 
Non-sexual  spores  in  sporangia,  which  in  some  genera  are  reduced 
to  conidioid  bodies. 

A.  Non-sexual  spores  formed  in  sporangia  in  many  cases  accom- 
panied by  conidiospores. 

(a)  Sporangia  (at  least  the  main  sporangia)  with  columella. 
Conidiospores  absent,  or  only  sparingly  found.  Zygospores 
naked,  or  only  covered  by  curled  outgrowths  of  the  sus- 
pensors.     I.  Mucorace^. 

(b)  Sporangia  without  columella;  zygospore  surrounded  by  a 
thick  covering  of  hyphae.     II.  Mortierellace^. 

B.  Non-sexual  spores  as  conidiospores.     Sporangia  exceptionally 
present. 

(a)  Conidiospores  single.  Zygospores  formed  directly  by  the 
united  gametes. 

1.  Sporangia    present    transitional    to    conidia;    sporangia 
monosporic  and  polysporic.     III.  Choanephorace^. 

2.  Sporangia  never  present;  parasitic  on  other  MUCOR- 
ALES.     IV.  Ch^tocladiace^. 

{b)  Conidia  in  chains  zygospore  formed  where  the  bent  ends 
of  the  gametes  unite.     V.  Piptocephalidace^. 

Non-sexual  spores  as  true  conidiospores  borne  singly  at  the  end  of 
conidiophores.     VI.  Entomophorace^. 

Family  i.  Mucorace^. — The  mycelium  of  the  true  moulds  is 
homogeneous,  or  it  becomes  heterogeneous  through  differentiation  into 
aerial  and  nutritive  hyphae.  Non-sexual  reproduction  by  the  forma- 
tion of  endospores  in  sporangia.  The  sporangia  here  may  be  simple  or 
branched.  The  sporangia  are  all  alike,  or  there  are  as  in  Thamnidium 
two  different  types  known  as  megasporangia  and  microsporangia.  The 
larger  sporangia  have  a  columella,  while  the  smaller  ones  are  mostly 
without  a  columella,  but  occasionally  a  columella  is  present.  The 
formation  of  conidiospores  is  unknown  in  the  family.  The  zygospore 
may  arise  by  the  fusion  of  two  similar  gametes  formed  from  the  same 
mycelium  (homogamic  hermaphrodites)  or  by  the  union  of  two  slightly 
dissimilar  gametes  the  product  of  the  same  myceUum  (heterogamic  her- 
mophrodites),  or  it  arises  by  the  conjugation  of  similar  gametes  (+  and 
—  races)  from  two  distinct  mycelia  (heterothallic  and  homogamic). 


98 


MYCOLOGY 


The  important  genera  of  the  family  are  Miicor,  Rhizopus,  Phycomy- 
ces,  Ahsidia,  Sporodinia,  Thamnidium,  Dicranophora,  Filaira  and  Pilo- 
boliis.  The  genus  Mucor,  a  key  for  the  identification  of  the  species  will 
be  given  at  the  end  of  the  book,  was  estabhshed  in  1729  by  Micheli. 
The  genus  may  be  divided  into  three  groups  of  species.  The  first 
division  includes  those  species  with  unbranched  sporangiophores,  such 
as  Mucor  mucedo.  The  second  group  comprises  the  moulds  with  clus- 
tered branches  of  the  sporangiophores,  as  Mucor  cor ymbifer,  M.  erectus, 
M.  fragilis,  M.  pusillus,  M.  racemosus,  and  M.  tenuis.  The  third  sec- 
tion is  made  up  of  species  the  sporangiophores  of  which  show  sympodial 


Fig.  30. — Details  of  Chlamydomucor  racemosus  showing  oidia,  sporangia  and  zygo- 
spore formation. 


branching.     Such  are  Mucor  alternans,  M.  circinelloides,  M.  javanicus, 
M.  Rouxii  and  M.  spinosus.     (Also  consult  pages  695-702.) 

The  oldest  known  species,  Mucor  mucedo,  was  described  fully  for  the 
first  time  by  O.  Brefeld  in  1872.  Stiff  sporangiophores,  30  to  401J, 
thick,  arise  from  the  mycelium  and  are  2  to  15  cm.  in  height.  Each 
bears  a  single  globular  sporangium  100  to  200/i  in  diameter  and  the 
sporangial  wall  is  beset  with  fine  needles  of  calcium  oxalate.  The  spores 
are  ellipsoidal  3  to  6/i  by  6  to  12/i  with  faint  yellowish  cell  contents.  As 
previously  described,  conjugation  is  between  two  similar  gametes  from 
+  and  —  mycelia.     Mucor  racemosus,  also  known  as  Chlamydomucor 


MOULD    FUNGI  99 

racemosus  (Fig.  30),  shows  the  clustered  branching  of  the  sporangio- 
phore  and  in  addition  the  hyphae  are  marked  by  the  intercalary  forma- 
tion of  chlamydospores.  This  mould  produces  sporangiophores  8  to  20/^ 
thick  by  5  to  40  mm.  in  height,  bearing  brownish  sporangia  20  to  70/x  in 
diameter.  The  globular  colorless  spores  are  5  to  ?>^x  broad  by  6  to  lo/x 
in  length.  This  mould  which  grows  on  bread  and  decaying  vegetable 
matter,  and  if  cultivated  submerged  in  beer-wort,  the  hyphae  swell  ir- 
regularly and  a  large  number  of  transverse  septa  appear,  which  divide 
the  hyphae  into  barrel-shaped  portions.  These  cells  or  gemmae  can  be 
separated  readily,  and  when  free,  they  become  spheric  and  multiply  by 
budding,  as  in  the  true  yeasts,  and  the  submerged  spores  hiso  bud  and 
constitute  the  so-called  Mucor-yeast.  At  the  surface  of  the  liquid,  they 
develop  the  typic  mould  form.  Miicor  racemosus,  according  to  Hansen, 
is  the  only  mould  capable  of  inverting  cane-sugar  solution.  It  produces 
in  beer- wort  as  much  as  7  per  cent,  by  volume  of  alcohol.  Mucor  erectus, 
which  grows  on  decaying  potatoes,  produces  azygospores  as  well  as  zygo- 
spores. It  has  the  same  appearance  as  the  preceding  and  possesses  an 
active  power  of  fermentation.  In  beer-wort  of  ordinary  concentration, 
it  yields  up  to  8  per  cent,  by  volume  of  alcohol,  and  in  dextrin  solutions 
it  induces  alcoholic  fermentation.  Mucor  spinescens,  which  grows  on 
Brazil  nuts,  has  spiny  projections  on  the  rounded  upper  surface  of  the 
columella.  Mucor  (Amylomyces)  Rouxii  occurs  in  the  so-called 
"  Chinese  yeast,"  which  is  in  the  form  of  small  whitish  cakes,  consisting 
of  rice  grains  kneaded  together  with  assorted  spices.  These  cakes  are 
powdered  and  mixed  with  boiled  rice  upon  which  the  mycelium  grows, 
converting  the  rice  by  slow  degrees  into  a  yellowish  liquid  which  con- 
tains glucose  produced  by  the  diastatic  ferment  of  the  fungus. 

The  black  mould  Rhizopus  nigricans  {Mucor  stolonifer)  grows  on 
bread  and  other  organic  substrata  (Fig.  31).  Several  sporangiophores 
arise  from  a  single  point  of  origin,  namely,  at  the  top  of  a  mass  of  rooting 
(rhizoidal)  hyphae  which  constitute  an  adhesive  organ  or  oppressorium. 
Each  erect  stalk  bears  oblate  spheroidal  sporangia  with  distinct  colu- 
mella and  sporangiospores,  6  to  17/i  long.  Arising  from  the  base  of  the 
clustered  sporangiophore  is  a  horizontal  hyphae,  which  often  attains  a 
length  of  3  cm.  and  is  known  as  the  stolon,  or  stoloniferous  hypha. 
When  the  tip  of  this  stolon  comes  into  contact  with  the  substratum  a 
new  appressorium  is  formed  from  which  arises  a  number  of  sporangio- 
phores bearing  sporangia  (Fig.  31).     This  method  of  growth  enables  the 


MYCOLOGY 


black  mould  to  spread  rapidly  and  it  sometimes  chokes  out  other  moulds 
growing  in  competition  with  it  on  the  same  nutritive  medium.  In  1818, 
on  account  of  this  method  of  growth,  it  was  named  by  Ehrenberg 
Mucor  stolonifer.  Related  to  this  fungus  is  one  named  Rhizopus  ory- 
zecB  which  grows  in  Ragi.  The  fungus  Phycomyces  nitens  is  found  in 
empty  oil  casks,  on  oil  cakes  and  in  concentrated  fodder.  It  puts  forth 
stifif  sporangiophores  7  to  30  cm.  long  and  50  to  150/i  in  diameter  which 
bear  at  the  summit  black  globular  sporangia  0.25  to  i.o  mm.  in  diame- 
ter, filled  with  yellow-brown,  thick- walled  endospores,  16  to  30/i 
long  and  8  to  15/x  broad.     Its  zygospores  are  300/x  broad  and  their 


Fig.  31. — Black  Mould,  Rhizopus  nigricans.  A,  Mature  plant  showing  rhizoidal 
hyphse  {myc)\  stoloniferous  hypha  {st);  sporangiophores  (sph);  sporangia  (sp).  B, 
Younger  cluster  of  sporangiophores  and  sporangia.      (After  Gager.) 

borders  are  covered  with  many  forked  projecting  hyphae  known  as 
suspensoria.  Recently  H.  Burgeff^  has  studied  the  variability,  sex- 
uality and  heredity  of  Phycomyces  nitens  and  has  brought  his  cultural 
investigations  into  line  with  the  recent  developments  of  cytology  and 
genetics.  His  paper  should  be  read  by  all  students,  who  may  be 
interested  in  the  extension  of  the  methods  of  genetics  into  an 
investigation  of  the  lower  plants. 

The  genus  Absidia  includes  five  species.  In  these  fungi  the  suspen*- 
sors  are  borne  at  the  base  of  the  two  gamete  cells  which  fuse  to  form  the 
zygospore,  which  when  mature  is  covered  by  a  basket-like  covering  of 

1  BuRGEFF,  H.:  Untersuchungen  liber  Variabilitat,.  Sexualitat  und  Erblichkeit 
h&i  Phycomyces  nitens  Kuntze.  Flora,  Band  108:  353-448;  review  by  G.  V.  Ubisch 
(Dahlem)  in  Botanisches  Centralblatt,  Band  128,  Nr.  23:  630-632,  1915. 


MOULD    FUNGI 


Straight  appressoria,  which  hook  together  by  their  curved  extremities, 
thus  giving  additional  protection  to  the  zygospore.  Sporodinia  grandis, 
the  single  species  of  another  genus,  lives  on  large  fleshy  fungi  of  the 


Fig.  32. 


-Sporangia  of  i,  Thamnidium  elegans;  2,  3,  4,  Thamnidium  chcelodadioides ; 
5,  Chalocladium  Jonesii.      (After  Brefeld.) 


families  (Fig.  28)  Agaricace^,  Boletace^,  Clavariace^  and  Hy- 
DNACE^.  Its  sporangiophores  i  to  3  cm.  high  are  finally  brown  in  color 
and  dichotomously  branched.     The  .sporangia  are  spheric  with  a  deli- 


MYCOLOGY 


cate  sporangial  wall,  which  soon  disappears  leaving  the  spores  on  a 
hemispheric  columella.  These  spores  are  ii  to  70/x  broad.  The  300/x 
broad  zygospores  are  produced  from  similar  branches  of  a  dichotomously 
branched  zygosphore.  The  mycelium  of  the  species  of  Thamnidium 
enters  the  nutritive  substratum.  The  large  sporangia  are  terminal 
while  the  smaller  secondary  sporangia  are  borne  on  lateral  branches  in 
whorls  below  the  terminal  sporangium.     This  is  typically  seen  in  Th. 


Fig.  ^^. — Details  of  sporangia  and  sporangiophores  of  Pilobulus.  i,  P.  tnicro- 
sporus;  2,  P.  roridus;  3,  4,  5,  P.  anomalus;  6,  zygospore  of  P.  anomalus.  {After 
Brefeld.) 

elegans  (Fig.  32).  A  related  species  Th.  Fresenii  has  an  upright  termi- 
nal sporangiophore,  which  is  either  sterile,  or  ends  in  a  large  terminal 
sporangium,  while  the  smaller  sporangia  are  as  in  Th.  elegans.  In 
Th.  amoenum,  the  lateral  smaller  sporangia  are  borne  at  the  end  of 
coiled  secondary  sporangiophores.  The  secondary  sporangia  suffer 
reduction  in  Th.  ch(etocladioides  (Fig.  32)  which  in  addition  to  having  a 
straight  terminal  spine-like  hypha  in  place  of  the  terminal  sporangia  has 
some  of  the  lateral  microsporangia  replaced  by  sterile  branches.     The 


MOULD   FUNGI  IO3 

commonest  species  oi  Pilobolus  (Fig.  33)  is  P.  cryslaUinns  which  appears 
on  horse  dung.  It  has  a  few  short  feeding  hyphae  and  an  upright  spor- 
angiophore  swollen  at  the  extremity  by  gas  and  water  vapor  and,  there- 
fore, under  tension.  It  bears  at  its  extremity  a  flat  rounded  sporan- 
gium filled  with  sporangiospores.  An  explosion  of  the  sporangiophore 
causes  the  whole  sporangicum  to  be  shot  off  a  considerable  distance. 

Family  2.  Mortierellace^. — This  family  consists  of  two  genera 
Mortierella  and  Herpocladiella.  The  genus  Mortierella,  which  is  repre- 
sented by  a  coprophilous  species,  M.  Rostafinski,  has  a  sporangium 
borne  on  a  sporangiophore  which  arises  in  a  definite  way  from  a  snare  of 
hyphae  that  are  knotted  into  a  rounded  mass  at  its  base.  In  M.  cande- 
labrum, the  sporangiophore  is  branched  candelabra-like.  Brefeld  men- 
tions Mortierella  and  Rhizopiis  as  examples  of  the  carposporangiate 
ZYGOMYCETALES,  where  the  sporangiophores  appear  always  at 
predetermined  places  on  the  mycelium,  and  not  at  indefinite  points,  as 
in  the  majority  of  other  moulds. 

Family  3.  Choanephorace^. — Represented  by  a  single  genus 
Choanephora  and  a  single  species  infundibulifer  on  flowers  of  Hibiscus 
in  East  Indies. 

Family  4.  Chcetocladiace^. — This  is  a  small  family  of  one 
genus  {Chcetocladium)  and  two  species,  {Ch.  Jonesii  and  Ch.  Brefeldii) 
(Fig.  32)  which  live  parasitically  on  Mucor  mucedo  and  Rhizopus  nigri- 
cans. The  terminal  sporangia  of  Thamnidium  are  never  formed  and 
secondary  sporangia  are  reduced  to  the  unisporous  condition  suggesting 
conidiospores  with  pointed  branches  between  them. 

Family  5.  Piptocephalidac§.«. — Three  genera  Piptocephalis, 
Syncephalis -and  Syncephalastrum  are  recognized  in  Die  Natiirlichen 
PflanzenfamiHen.  The  eight  species  of  Piptocephalis  are  parasitic 
on  the  mycelia  of  Mucor,  Pilobolus  and  Chcetocladium  species  (Fig.  37). 
The  haustorial  hypha  flattens  itself  disc-like  on  the  outer  surface  of 
the  host's  hyphge  and  sends  five  rhizoida'l  branches  into  the  host  cells. 
An  erect  dichotomously  branched  conidiophore  bears  conidiospores 
in  globular  clusters  at  the  ends  of  its  principal  branches.  Some 
species  of  Syncephalis  are  parasitic  on  other  fungi;  but  S.  cordata 
grows  on  manure,  presumably  as  a  saprophyte. 

Family  6.  Entomophthorace.e. — The  mycehum  of  the  fungi  of  this 
family  is  more  or  less  richly  developed  and  fives  endozoically  in  animals, 
such    as   flies,    mosquitoes,    aphids,    and    seldom    saprophytically    as 


I04 


MYCOLOGY 


Basidioboliis  on  the  feces  of  frogs.  Non-sexual  reproductions  is  mainly 
by  means  of  unicellular  conidiospores  which  are  discharged  forcibly 
from  the  ends  of  tubular  conidiophores.  Sexual  reproduction  is  by  the 
conjugation  of  two  gametes  dissimilar  in  size,  heterogamic  and  thus  these 
fungi  connect  the  ZYGOMYCETALES  with  the  OOMYCETALES 
where  oogamous  reproduction  is  displayed.  The  zygospores  formed 
in  conjugation  are  spheric,  while  the  azygospores  formed  on  the 
mycelium  without  copulation  are  similar  to  the  zygospores  in  struc- 
ture  and   appearance.     The    family    includes    seven    genera,    includ- 


FiG.  34. — Fly  cholera  fungus  (Empusa  musca).  i,  Fly  enveloped  in  mycelium; 
2,  fungus  between  hairs  of  the  fly;  3,  conidiophores  and  conidiospores;  4,  germina- 
tion of  spores;  5,  formation  of  egg  in  Empusa  sepulchralis.  {After  Thaxter.)  See 
Henri  Coupin,  Atlas  des  Champignons,  Parasite  set  Pathogenes  de  1' Homme  et  des 
Animaux,  1909. 

ing  Empusa  and  Entomophthora,  which  may  be  chosen  as  types  for 
discussion. 

The  mycehum  of  Empusa  musccB  (Fig.  34)  is  parasitic  in  the 
bodies  of  flies,  destroying  them  in  large  numbers  by  an  epidemic  in  the 
fall,  known  as  fly-cholera.  The  short  hyphae  frequently  bud  like 
yeast  cells.  The  conidiophores  break  through  to  the  surface  of  the 
insect's  body,  where  the  conidiospores  18  to  25/x  broad  by  20  to  30/^ 
long  are  forcibly  discharged.  These  spores  bore  their  way  through  the 
chitinous  covering  of  a  healthy  fly  by  means  of  a  germ  tube  and  the 


MOULD    FUNGI  105 

hyphffi  which  enter  the  body  of  the  tly  bud  hke  yeast  cells,  which  are 
carried  to  all  parts  of  the  insect's  body.  Later  the  parasitic  hyphse 
arise  from  the  gemmae.     Resting  spores  are  unknown. 

Entomophthora  is  a  genus  of  fungi  inclusive  of  thirty  species  found 
on  various  insects  in  Europe  and  North  America.  Entomophthora 
sphcerosperma  has  a  richly  branched  nutritive  mycelium,  which  grows 
through  the  body  of  insects.  After  the  death  of  the  host,  the  hyphae 
break  through  the  surface  in  connected  strands  part  of  which  attach 
the  larva,  or  insect's  dead  body,  to  the  substratum  and  part  form  a 
thick  white  mantle  over  the  surface. 

The  conidiophores  are  in  branching  bundles.  The  conidiospores 
are  elongated  ellipsoidal,  5  to  8ju  broad  by  15  to  26ju  long.  Secondary 
and  tertiary  conidia  are  found.  The  resting  spores  produced  as  azy- 
gospores  are  spheric  and  20  to  35^1^  broad  with  a  smooth  yellow  wall. 
It  grows  on  larvae,  especially  frequent  on  the  cabbage  worm  Pieris 
brasskce  in  Europe  and  North  America. 

BIBLIOGRAPHY  OF  THE  ZYGOMYCETALES 

This  is  not  intended  to  be  a  complete  list  of  the  works  dealing  in  whole  or  in 

part  with  the  mould  fungi,  but  only  a  list  of  the  works  which  may  prove  helpful  to 

the  student  of  mycology. 

Rainier,  G.:  Etude  sur  les  Zygospores  des  Mucorinees,  These  pr^sent^e  a  I'l^cole 
de  Pharmacie.  Paris,  pp.  136,  pis.  i-ii;  Observations  sur  les  Mucorinee. 
Annales  des  Sciences  naturelles,  ser.  6,  1-15:  70-104,  pis.  4-6.  Sur  les  zygo- 
spores des  Mucorinees.  Annales  des  Science  naturelles,  vi  ser.,  I:  18,  1883; 
Nouvelles  observations  sur  les  zygospores  des  Mucorinees,  do.,  I:  ig,  1884. 

Blakeslee,  Albert  F.  :  Sexual  Reproduction  in  the  Mucorineae.  Proceedings 
American  Academy  "Arts  and  Sciences,  xl:  205-319  with  4' plates  and  bibli- 
ography, The  Biological  Significance  and  Control  of  Sex.  Science,  new  ser. 
x.xv:  366-384,  March  8, 1907;  Papers  on  Mucors  (a  review).  Botanical  Gazette, 
47:  418-423,  May,  1909;  Heterothallism  in  Bread  Monld,  Rhizopus  nigricans. 
Botanical  Gazette,  43:  415-418,  June,  1907;  A  Possible  Means  of  Identifying 
the  Sex  of  (+)  and  (  — )  Races  in  the  Mucors.  Science,  new  ser.  xxxvii:  880- 
881,  June  6,  1913;  On  the  Occurrence  of  a  Toxin  in  Juice  Expressed  from  the 
Bread  Mould,  Rhizopus  nigricans.  Biochemical  Bulletin  II:  542-544,  July, 
1913;  Conjugation  in  the  Heterogamic  Genus  Zygorkynchiis.  Mycologisches 
Centralblatt  II:  241-244,  1913;  Sexual  Reactions  between  Hermaphroditic  and 
Dioecious  Mucors.  Biological  Bull.,  xxix:  87-102,  August,  1915;  Zygospores 
and  Rhizopus  for  Class  Use.     Science,  new  ser.  xlii:  768-770,  Nov.  26,  1915. 

Brefeld,  O.:  Botanische  Untersuchungen  liber  Schimmelpilze,  Heft  i,  Zygomy- 
ceten,  pp.  1-64,  Taf,  1-6,  1872;  Untersuchungen  aus  den  Gesamtgebiete  der 
Mykologie,  ix,  1891. 


Io6  MYCOLOGY 

Buchanan,  Estelle  1).,  and  Buchanan,  Robert    E.:  Household  Bacteriology, 

1914:  66-72. 
DE  Bary,  a.:  Comparative  Morphology  and  Biology  of  the  Fungi  and  Bacteria, 

1887:  144-160. 
Englee,  a.  and  Gilg,  Ernst.:  Syllabus  der   Pflanzenfamilien,  7th  Edition,  191 2: 

37-38. 
Gortner,  Ross  A.  and  Blakeslee,  A.  F. :  Observations  on  the  Toxin  of  Rhizopus 

nigricans.     American  Journal  of  Physiology,  xxxiv:  354-367,  July,  1914. 
Jorgensen,  Alfred:  Microorganisms  and    Fermentation,  3d    Edition,  1900:  97- 

115- 
Keene,  Mary   L.:  Cytological    Studies    of  the  Zygospores  of  Spordinia  grandis. 

Annals  of  Botany,  xxxviii:  455,  1914. 
Klocker,  Alb.:  Fermentation  Organisms,  1903:  170-186. 
Lafar,  Franz:  Technical  Mycology,  II,  part  i:  1-30,  1903. 
Lendner,  Alf.:  Les  Mucorinees  de  la  Suisse.  Materiaux  pour  la  Flore  Crypto- 

gamique  Suisse  III,  Ease,  i:  1-177,  1908. 
Schroter,  J.:  Mucorineae,  Die  natlirlichen  Pflanzenfamilien,  I,  Teil  i.     Abt.  119- 

142,  1897. 
Stevens,  F.  L.:  The  Fungi  which  Cause  Plant  Disease,  1913:  101-108. 
Swingle,  Deane  B.:  Formation  of  the  Spores  in  the  Sporangia  of  Rhizopus  nigri- 
cans and  of  Phycomyces  nitens.     Bureau  of  Plant  Industry  No.  37,  1903  with 

6  plates. 
Underwood,  Lucien  M.:  Moulds,  Mildews  and  Mushrooms,  1899:  24-28. 
VON  Tavel,  F.:  Vergleichende  Morphologic  der  Pilze,  1892:  25-40. 
Wettstein,  Richard  R.  von:  Handbuch  der  systematischen  Botanik,  1911:  160- 

164. 


CHAPTER  XII 

OOSPORE-PRODUCING  ALGAL  FUNGI 

ORDER  II.  OOMYCETALES 

The  fungi  of  this  order  were  derived  probably  from  some  ancestor, 
or  ancestors,  which  through  the  loss  of  chlorophyll  became  dependent 
on  extraneous  supplies  of  organic  food.  If  we  look  for  such  an  ancestral 
form  among  the  algae,  we  find  that  it  must  have  been  related  to  Vau- 
cheria,  if  not  identic  with  that  filamentous  siphonaceous  green  alga 
with  reproductive  organs,  as  oogonia  and  antheridia.  Vaucheria  is  a 
unicellular  filamentous  sparingly  branched  cell  with  a  thin  cell  wall  and 
multinucleate.  Hence  it  is  sometimes  called  a  coenocyte.  Similarly, 
the  structural  features  of  the  more  primitive  Oomycetales  are  like 
Vaucheria,  but  the  absence  of  chlorophyll  is  distinctive.  The  forma- 
tion of  non-sexual  sporangia  with  the  formation  of  zoospores,  or  swarm 
spores,  known  as  zoosporangia  is  a  feature  of  the  fungi  of  this  order. 
As  there  is  a  pronounced  difference  between  the  male  and  female  sexual 
organs,  oogamous  reproduction  is  the  rule.  The  oogonium  is  compara- 
tively large  and  contains  one  or  more  oospheres,  which  are  fertilized 
by  the  sperm  cell,  which  swim  to  it  by  cilia,  creep  to  it,  or  are  carried 
into  the  oogonium  through  a  fertilization  tube.  Sexual  reproduction  in 
these  fungi  has  been  investigated  cytologically  by  a  number  of  students, 
and  they  have  found  that  the  nuclear  changes  concomitant  with  fertili- 
zation are  characteristic.  Albugo  Candida,  A.  lepigoni,  Peronospora 
parasitica,  Plasmopara,  Pythium  and  Scleras  para  show  a  single  large  cen- 
tral oosphere  with  a  single  nucleus,  while  the  remaining  nuclei  pass  from 
the  gonoplasm  into  the  periplasm.  A  process  is  sent  into  the  oogonium 
from  the  antheridium  and  a  single  male  nucleus  passes  into  the  oogo- 
nium. A  cell  wall  is  developed  about  the  oospheres  and  the  male  and 
female  nuclei  unite,  while  the  periplasm  is  used  in  the  formation  of  the 
spore  wall  (episporium).  The  ripe  oospore  has  a  single  nucleus  in 
Peronospora  parasitica,  while  in  Albugo,  it  becomes  multinucleate  after 
nuclear  division.     A  central  oosphere  (gonoplasm)  surrounded  by  peri- 

107 


Io8  MYCOLOGY 

plasm  occurs  in  Albugo  blitl  and  .1.  portulacce  and  the  oosphere  is 
multinucleate  and  the'  nuclei  present  fuse  in  pairs  with  a  number  of 
sperm  nuclei  which  enter  from  the  antheridium.  The  oospore  which 
arises  is  multinucleate.  This  method  is  considered  by  mycologists  to 
be  the  primitive  one  as  displayed  in  these  two  species,  the  uninucleate 
oospheres  of  the  first-named  species  having  been  derived  from  the  multi- 
nucleate. An  intermediate  position  is  occupied  by  Albugo  tragopogonis, 
where  at  first  the  oosphere  is  multinucleate  but  by  the  degeneration  of 
all  but  one  female  nucleus  becomes  uninucleate.  Claussen^  finds  that 
Sa'prolegnia  monoica  develops  both  antheridia  and  oogonia,  the  latter 
at  first  being  filled  with  protoplasm  and  many  nuclei  which  wander  to 
the  periphery  and  undergo  degeneration  with  a  few  nuclei  left  over. 
These  nuclei  divide  once  mitotically.  Around  these  daughter  nuclei 
the  protoplasm  collects  to  form  the  egg  cells.  Each  egg  has  a  single 
nucleus  near  which  is  the  coenocentrum  of  Davis,  but  which  Claussen 
thinks  is  a  true  centrosome.  The  simple  or  branched  antheridia  form 
germ  tubes  which  enter  the  wall  of  the  oogonium  and  a  single  male 
nucleus  fuses  with  the  nuclei  of  the  egg  cells  to  form  the  oospore. 
Claussen  contrasts  the  life  cycle,  as  determined  by  his  investigations, 
with  those  of  Trow  in  the  following  diagrammatic  presentation: 

Trow  Diploid  Haploid  Diploid 


/      Antheridium — Male  nucleus         \ 

/  \ 

Oospore,  Mycelium  Oospore 

Multinucleate      \  / 

\Oogonium — Egg  cell — Egg  nucleus/^ 

Claussen  Haploid  Diploid. 

Strasburger  considers  that  the  superfluous  nuclei  in  the  oogonia  and 
the  antheridia  are  comparable  with  the  superfluous  egg  nuclei  of  certain 
of  the  brown  seaweeds  belonging  to  the  family  Fucace^.  When  the 
oospores  germinate,  they  either  produce  directly  a  mycelium,  or  give 
rise  to  zoospores.  The  fungi  of  this  order  are  essentially  parasitic, 
being  found  in  this  condition  as  endophytic  parasites,  or  as  endozoic 
parasites  on  fishes  and  insects  and  Euglena. 

1  Claussen,   P.:  Ueber  Eintwicklung  und  Befructung  bei  Saprolegnia  monoica. 
Festschrift  der  Deutsch.  Bot.  Gesellsch.,  xxvi;  144-161  with  2  plates,  1908. 


OOSPORE-PRODUCING   ALGAL   FUNGI  IO9 

Key  to  Families  of  the  Order  Oomycetales 

A.  Zoosporangia,  oogonia  and  antheridia  present;  conidia  absent. 

(a)  Mycelium  well  developed. 

1.  Antheridium  forming  motile  spermatozoids,  which  enter  the 
oogonium.     Family  i.  Monoblepharidace^. 

2.  Antheridium  not  forming  spermatozoids,  fertilization  through 
an  antheridial  tube,  or  beak.     Family  2.  Saprolegniace^. 

(b)  Mycelium  poorly  developed,  sometimes  represented  by  a  single 
cell. 

1.  Fruit  body  as  a  single  cell  or  by  division  forming  a  sporangial 
sorus;  parasites  on  algae,  protozoans,  rarely  on  flowering 
plants.     Family  4.  Chytridiace^. 

2.  Fruit  body  through  division  a  chain  of  cells  which  develop 
sometimes  into  zoosporangia,  sometimes  into  antheridia  and 
oogonia.     Family  5.  Ancyclistace^. 

B.  Conidia  present.     Family  3.  PERONOSPORACEiE. 

The  following  descriptions  of  the  above  five  families  are  presented 
in  order  to  introduce  the  student  to  the  characters  which  fundament- 
ally distinguish  them.  Therefore,  all  generic  keys  are  omitted  because 
the  introduction  of  them  under  each  family  would  increase  the  size  of 
the  book  unduly. 

Family  i.  Monoblepharidace^. — This  family  is  represented  by 
the  genera  M onoblepharis  and  Gonapodya.  The  genus  Monoblepharis 
is  represented  by  two  species  of  which  M.  sphcBrica  is  the  most  com- 
mon. It  is  an  aquatic  fungus  found  growing  saprophytically  on  dead 
animal  and  plant  parts  under  water.  The  hyphae  of  the  mycehum 
are  tubular,  branched  and  unicellular.  The  swarm  spores  (zoospores), 
which  are  formed  much  as  in  Saprolegnia,  have  only  a  single  flagellum. 
The  oogonia  are  either  terminal  in  position  or  interstitial  and  there  is 
no  differentiation  of  an  outer  periplasm,  but  the  whole  protoplasm 
of  the  oogonium  contracts  to  form  an  oosphere.  Later  a  pore  appears 
at  the  apex  of  the  oogonium  through  which  the  uniciliate  spermatozoids 
enter  to  fertilize  the  egg  cell.  The  antheridium  in  M.  sphcBrica  appears 
as  a  penultimate  cell  immediately  below  the  oogonia.  An  opening  is 
formed  at  the  top  through  which  the  spermatozoids  escape.  The 
oosphere  on  fertilization  becomes  an  oospore.     Because  of  the  aquatic 


no  MYCOLOGY 

habit  and  formation  of  motile  spermatozoids,  Brefeld  considers  Mono- 
blepharis  to  be  the  most  primitive  of  the  Oomycetales. 

Family  2.  Saprolegniace^. — The  members  of  this  family,  as 
their  name  indicates,  are  saprophytes  on  both  dead  plants  and  animals 
in  water  with  the  exception  of  the  fungus  which  causes  the  salmon 
disease  and  it  is  both  a  saprophyte  and  a  facultative  parasite.  The 
hyphae  in  the  vegetative  condition  are  relatively  large,  arising  from 
delicate  rhizoids  which  penetrate  the  substratum.  Swarm  spores 
which  are  biciliate  are  formed  in  terminal,  long,  tubular  zoosporangia 
opening  by  an  apical  pore  through  which  the  zoospores  crowd  their 
way  out  into  the  water.  Sometimes,  as  they  escape,  they  collect  into 
ball-shaped  masses  which  are  caused  to  slowly  roll  about  by  the  activity 
of  the  cilia.  The  female  sexual  organs,  the  oogonia,  are  terminal  on 
the  branches  of  the  thallus  hyphae.  Several  oospheres  without  dis- 
tinction of  periplasm  are  formed  inside  of  a  single  oogonium,  and 
sometimes,  as  many  as  thirty  or  forty  are  found.  The  antheridia, 
which  are  club-shaped,  are  formed  on  slender  branches  of  the  mycelium 
which  also  bear  the  oogonia,  or  which  are  distinct  from  those 
which  are  oogonial  bearers.  These  antheridia  approach  the  oogonia 
and  an  antheridial  beak  is  formed  which  penetrates  the  wall  of  the 
oogonium  and  comes  into  contact  with  the  oospheres  by  growing  from 
one  oosphere  to  another.  Sometimes  the  antheridia,  as  in  Saprolegnia 
monilifera,  are  not  produced  at  all  and  the  oogonia  develop  partheno- 
genetic  oospores  which  germinate  after  a  rest  period  of  a  few  days  to 
several  months.  The  series  representing  reduction  in  sexuality  begins 
with  such  forms  as  Saprolegnia  monoica  with  an  oogonium  and  an 
antheridium  which  develops  a  fertihzing  process  through  Achlya 
polyandra,  which  forms  antheridial  branches  which  do  not  touch 
the  oogonia,  to  Saprolegnia  monilifera  without  any  trace  of  antheridia. 
Androgynous  forms  are  those  in  which  the  same  hyphal  branch 
develops  both  antheridia  and  oogonia  and  the  diclinous  species 
like  Saprolegnia  dioica  and  Achlya  oblongata  ar.e  those  in  which  the 
antheridia  and  oogonia  are  borne  on  distinct  branches. 

Saprolegnia  ferax  usually  attacks  only  fishes,  tadpoles  and  the 
spawn  of  frogs.  It  appears  on  aquarium-kept  fishes  on  the  sides  of 
the  body  at  the  tail  end,  or  among  the  gills.  In  the  latter  place,  if 
abundant,  it  frequently  causes  asphyxiation  and  before  this  state  is 
final  the  fish  turns  over  on  its  back  and  rises  to  the  surface.     In  the 


OOSPORE-PRODUCING   ALGAL    FUNGI  III 

experience  of  the  writer,  immersion  of  the  diseased  fish  in  strong  brine 
in  many  cases  brings  about  a  cure,  if  the  growth  of  the  fungus  is  not 
too  great,  Petersen'^  observed  a  sick  bream  in  the  lake  of  Fure  So 
with  a  wound  quite  overgrown  with  Saprolegnia  hyphge  and  he  has 
found  frog  eggs  which  were  attacked,  the  hyphae  growing  in  the  jelly 
around  the  eggs,  penetrating  into  them.  The  fungus  can  be  raised  in 
the  laboratory  on  dead  fishes  by  allowing  tap  water  to  slowly  flow  over 
them  in  a  jar.  A  few  days  are  necessary  to  secure  a  copious  growth. 
Frogs  which  die  under  the  ice  in  winter  for  lack  of  oxygen  float  to  the 
surface  in  the  spring  entirely  covered  by  this  fungus.  It  thrives 
best  in  the  early  stages  of  decay,  for  as  putrefaction  advances  bacteria 
and  infusoria  increase  to  such  an  extent  as  to  check  the  growth  of  the 
fungus.  When  air  insects,  such  as  gnats,  fall  into  lake  or  pond  water 
in  great  numbers,  species  of  Saprolegnia,  Achyla  and  Aphanomyces 
appear  in  great  numbers  and  seem  to  form  a  gray  felt  on  the  surface. 

The  vegetable  materials  on  which  the  Saprolegniace^  mostly  Hve 
are  branches  and  shoots  of  trees,  except  Salix,  owing  to  presence  of 
salicin,  which  fall  into  the  water.  Second  in  importance  are  half- 
rotten  rhizomes  of  Calla,  half-rotten  leaves  and  leaf  stalks  of  Nuphar 
and  Nyniphcea  and  other  parts  of  aquatic  plants  which  float  on  the 
surface.  Species  of  the  genus  Achlya  are  mostly  associated  with  such 
materials.  Achlya  polyandra  have  been  repeatedly  found  by  me  on  the 
fruits  of  Osage  oranges  which  have  fallen  into  the  pond  at  the  Univer- 
sity of  Pennsylvania.  The  most  favorable  environmental  conditions 
seem  to  be  the  absence  of  air  about  the  hyphae,  quiet,  still,  pure  water, 
that  does  not  contain  much  iron  and  a  relatively  open  light  surface. 
Low  temperature  conduces  to  the  formation  of  oogonia,  which  also 
keeps  in  check  other  competing  organisms  (Fig.  35). 

Family  3.  Peronosporace^. — This  family  is  rich  in  parasitic 
forms  which  may  be  accounted  as  the  cause  of  important  diseases  of 
cultivated  plants.  The  hyphae  of  the  mycelia  are  irregularly  and  copi- 
ously branched  and  are  found  mainly  in  the  intercellular  spaces  of  the 
host  tissue  sending  short  branches  called  haustoria  into  the  adjoining 
living  cells.  These  haustoria  maybe  glohulsLV  (Albugo  =  Cystopus), 
club-shaped  (Peronospora  corydalis),  branched  (Plasmopara)  (Fig.  36), 
or   branched   and   snarled    {Peronospora).     Septa   are   absent   except 

1  Petersen,  Henning  E.  :  An  Account  of  Danish  Fresh-water  Phycomycetes. 
Annales  Mycologici,  viii,  No.  5,  1910. 


112  MYCOLOGY 

when  the  reproductive  organs  are  formed.  Non-sexual  spores,  or 
conidiospores,  are  borne  on  conidiophores  which  may  remain  within 
the  host  (Albugo  =  Cystopus),  or  grow  beyond  the  surface.  They  may 
be  either  simple  or  branched.  These  conidiospores  either  germinate, 
as  in  Phytophthora  infestans  and  Peronospora  nivea  by  means  of  zoo- 


Fig.  35. — I,  Zoosporangium  of  Achlya  racemosa;  2,  escape  of  zoospores;  3,  fly- 
covered  by  mycelium;  4,  zoospores  of  fungus;  5,  Achlya  ferax  with  zoosporangia  and 
zoospores;  6,  Achlya  proUfera,  24  hours  after  germination  of  zoospores.  7,  Achlya 
monoica,  with  antheridia  and  oogonia;  8,  Achlya  conlorta.  {After  Henri  Coupin, 
Atlas  des  Champignons  Parasites  el  Pathogenes  de  I' Homme  et  des  Animaux,  pi.  xviii, 
1909.) 


spores  which  escape  or  by  the  protoplasm  escaping  {plasmato parous),  as 
in  Peronospora  densa,  or  by  germ  tubes,  which  in  some  species  {Perono- 
spora lactuca)  appear  at  the  end  of  the  spore  (acroblasfic) ,  or  at  the 
side  of  the  conidiospore  (pleuroblaslic) ,  as  in  Peronospora  radii.  The 
oogonia  and  antheridia,  which  are  also  present,  are   formed   in    the 


OOSPORE-PRODUCING    ALGAL   FUNGI 


113 


tissues  of  the  host.  The  different  kinds  of  nuclear  fusion,  which 
accompany  fertiUzation,  have  been  described  previously.  The  oospore, 
which  is  formed,  acts  as  a  zoosporangium  in  some  cases  for  it  gives 
rise  to  numerous  spores;  or  in  other  cases  it  produces  a  germ  tube. 
In  most  of  the  forms,  the  oogonium  contains  a  mass  of  protoplasm 
known  as  the  oosphere.     This  is  divisible  into  an  outer  clearer  por- 


FiG.  36. — Plasmopora  vilicola.  A,  Conidiophore  with  conidiospores  (nearby 
oospores);  B,  Haustoria;  C,  Swarmspore  formation.  A,  950/1;  B.  C,  600/1.  {After 
Millardcl  in  Die  naliirlichen  Pflanzenfamilien  I.  i,  p.  115), 


tion,  the  periplasm,  and  a  denser  more  granular  central  portion,  the 
gonoplasm.  After  fertilization,  the  oospore  develops  a  thick  wall  of 
two  layers,  an  extine  and  intine,  and  becomes  a  resting  spore.  It 
accumulates  fatty  substances,  which  are  utilized  when  the  spore 
germinates  in  the  spring  after  a  long  winter's  rest.  The  family  has 
had  many  revisions  and  in  order  to  simplify  matters  Pythium  and 
Albugo  (Fig.  37),  which  are  placed  in  separate  families  by  some 
8 


114 


MYCOLOGY 


authors,  are  placed  in  the  family  Peronosporace^.  Details  of  the 
important  forms  which  cause  plant  diseases  will  be  given  in  the  third 
part  of  this  book.  These  fungi  will  be  referred  to  under  each  genus 
following  the  systematic  generic  key  which  is  here  given. 

Generic  Key  of  the  Family.     PERONOSPORACEiE 


Mycelium  of  these  fungi  parasitic  or  saprophytic  in  plant  tissues; 
zoosporangia  as  distinct  organs  producing  biciliate  zoospores. 

Zoospores    formed    out    of    protoplaem 

which  escapes  out  of  the  conidia.  i.  Pythium. 

Zoospores  formed  within  the  zoosporangia. 

2.  Pythiacystis. 

Zoospores  elongate.  3.  N emato sporangium . 

^_^  Mycelial  hyphae  branching   non-septate 

/    ^    usually  coarse,  of  strictly  parasitic  habit. 

Conidiophores  short,  thick,  subepidermal, 
conidia  in  chains.  4.  Albugo 

Conidiophores  longer  superficial,  simple 
or  branched,  conidia  not  in  chains. 
Conidiophores      scorpioid     cymosely 
branched      conidiospores     developing 
swarmspores.  5.  Phylophthora.^ 

Conidiophores  simple,  or  branched 
monopodially;  conidia  sprouting  as  a 
plasma,  or  by  swarm  spores.  Con- 
idiophores regularly  branched. 

Conidiophores  simple  erect  with  a 
swollen  end  (basidia-like)  bearing 
short  sterigma-like  branches  of  equal 
length.  6.  Basidiophora. 

Conidiophores  with  lateral  branches  developed  normally  of 
unequal  length.  Conidiophores  stout,  with  few  branches, 
oospore  united  to  wall  of  oogonium.  7.  Sclerospora. 

Conidiophores  slender,  freely  branched  persistent;  oospore 
free.  [  8.  Plasmopara. 

Conidiophores  with  forking  branches;  conidiospores  sprout- 
ing with  a  germ  tube.     Upper  end  of  conidiospore  with  a 


Fig.  37. — White  rust 
Cystopus  (Albugo)  portula 
cecB,  on  purslane,  Portulaca 


oleracea 
Harbor, 
1915-) 


(Cold       Spring 
L.   I.,    July     24, 


OOSPORE-PRODUCING   ALGAL   FUNGI 


115 


papilla   through   which   the  germ   tube  grows   (acroblastic). 

g.  Bremia. 
Conidiospores  without  papilla;  pleuroblastic.  10.  Peroiwspora. 

The  most  important  species  of  these  genera  from  the  standpoint  of 
the  plant  pathologist  are  the  following  enumerated  below  with  their 
common  English  names  where  such  have  been  given. 


English  name 


Host  plant 


Pythium  de  Baryantim 

Pythiacystis  citriopthora 

Albugo  {Cystopus)  Candida... 
Albugo  (Cystopus)  portulaca; . 

Phytophthora  cactorum 

Phytophthora  infestans 

Phytophthora    phaseoU    (Fig. 

44)- 
Plasmopara  cubensis 


Damping-off  fungus.. .  . 
Brown  rot  of  lemon.. .  . 
White  rust  of  crucifers. 
White  rust  of  purslane. 
Mildew  of  succulents.. . 
Late  blight  of  potato.. . 


Plasmopara  Halstedii 


Plasmopara  viticola  ... 

Bremia  ladiica 

Peronospora  effusa 

Peronospora  parasitica Downy  mildew  of  crucifers! 

Peronospara  Schleideniana. .  .    Onion  mildew 


Downy  mildew  of  beans. 


Seedlings 
Lemon  fruits 
Cruciferous  plants 
Portulaca  oleracea 
Cacti,  etc. 
Potato 
Lima-bean 


Downy     mildew     of    cu-   Cucumber 
cumber. 


and 


Downy  mildew  of  grape. . 
Downy  mildew  of  lettuce. 
Mildew  of  spinach 


Helianthus    annuiis 

H.  tuberosus 
Grape  vine 

Cynara,  Cineraria,  Lactuca 
Spinach 
Cabbage 
Onion 


CHAPTER  XIII 
OOMYCETALES    (CONTINUED) 

Family  4.  Chytridiace.e. — This  family  according  to  some  authors 
is  made  to  include  six  families  which  are  here  reduced  to  six  subfamilies. 
It  includes  fungi  of  short  vegetative  duration,  which  may  be  a  few  days 
in  length.  The  swarm  spores  quickly  give  rise  to  new  generations. 
The  resting  period  is  represented  in  the  case  of  the  endophytic  para- 
sites by  the  time  which  elapses  between  the  growth  of  two  successive 
crops  of  the  host  plants.  The  majority  of  the  species  of  the  family 
are  true  parasites,  partly  endobiotic,  partly  epibiotic,  and  a  few 
are  saprophytes.  Half  of  the  plant  parasites  live  in  fresh-water 
algae,  nearly  as  many  in  flowering  plants,  some  of  which  are  in 
aquatic  plants,  some  in  swamp  plants.  About  ten  species  are  found 
on  marine  algse.  All  species  are  microscopically  small,  yet  they 
cause  galls,  dwarfing,  dropsy  and  crusts  of  the  host  plants.  The 
mycelium  is  absent  or  in  the  form  of  slender  protoplasmic  filaments, 
occasionally  as  distinct  one-celled  hyphae.  The  cell,  which  produces 
the  fruit  body,  frequently  serves  as  the  chief  nutritive  organ.  Later, 
it  divides  to  form  zoospores.  The  true  mycelium  has  weak  develop- 
ment. The  short  germ  tube  merely  serves  as  an  organ  by  which  the 
parasite  gains  entrance  to  the  host  cell,  and  in  the  endophytic  forms,  it 
disappears  quickly,  but  in  the  epiphytic  species,  it  serves  as  an  haustor- 
ium,  sometimes  with  rhizoidal  extensions.  In  the  better-developed 
forms  of  Cladochytrie^,  the  slender  mycelium  serves  to  carry  the 
fungus  from  cell  to  cell  of  the  host.  The  sporangia  are  always  zoo- 
sporangia  which  develop  swarm  spores,  or  zoospores.  They  are  thin- 
walled  and  quickly  mature,  or  they  are  thick-walled  and  form  resting 
sporangia.  Sexual  spores  are  formed  in  only  a  few  types  and  the  differ- 
ence between  antheridia  and  oogonia  is  morphologically  little  pro- 
nounced. The  swarm  spores  have  as  a  rule  a  single  flagellum,  rarely 
do  they  have  no  such  locomotory  appendages.  The  sexually  produced 
oospores  have  the  appearance  of  resting  sporangia  with  the  empty 
antheridium  attached  as  an  appendage.     Few  of  these  fungi  attack  our 

116 


OOMYCETALES  II7 

cultivated  plants,  but  where  the  attempt  is  made  to  grow  alga^  and 
other  water  plants,  the  fungi  of  this  family  occasionally  do  considerable 
damage. 

As  an  example  of  the  first  subfamily  Olpide.e,  may  be  chosen 
Olpidiuni  endogenum,  which  lives  in  the  cells  of  desmids  and  kills 
them.  The  zoosporangium  found  in  desmid  cells  are  oblate  spheroids 
and  develop  a  long  tube  which  projects  out  of  the  desmid  cell  through 
which  the  zoospores  with  a  single  cilia  escape  into  the  water.  O.  ento- 
phytum  is  parasitic  in  such  filamentous  algse  as  Vaucheria,  Clado- 
phora,  Spirogyra.  Olpidiopsis  saprolegnm  lives  in  the  elongated 
cells  of  Saprolegma,YiXod\xcmg  enlargements  in  the  hyphae  of  the  fun- 
gous host.  The  swarm  spore  bores  a  hole  in  the  cell  wall  of  its  host 
and  swells  out  into  a  zoosporangium  which  develops  a  tube  through 
which  the  biciliate  swarm  spores  escape  into  the  water. 

The  subfamily  Synchytrie^  includes  most  of  the  fungi  which 
attack  the  higher  plants.  Such  are  Synchytrimn  decipiens  on  the 
hog  peanut  (Amphicarpea  monoica);  S.fulgens  on  the  evening  primrose 
{Oenothera  biennis);  S.  stellarice  on  Stellaria;  S.  succiscB  on  Succisa 
pratensis;  S.  taraxaci  on  dandelion;  S.  vaccinii  causing  a  gall  on  cranber- 
ries, Pycnochytriiini  globosum  on  violet,  wild  strawberry,  blackberry  and 
maple  seedlings.  P.  myosotidis  occurs  on  certain  members  of  the 
borage  and  rose  families. 

Cladochytrium  tenue  of  the  subfamily  Cladochytrie^  lives  in  the 
subaquatic  tissues  of  the  sweet  flag,  Acorus  calamus,  flag  Iris 
pseudacorus  and  a  grass,  Glyceria  aquatica.  Its  mycelium  is  widely 
distributed  in  the  cells  of  its  hosts.  Spheric  sporangia  18 fx  wide  and 
sometimes  66/x  are  formed  as  intercalary  enlargements  of  the  mycelium, 
or  they  are  formed  at  the  end  of  the  hyphae,  with  a  colorless  supporting 
cell.  They  give  rise  to  a  short  tube-like  mouth  which  breaks  out  of 
the  host  cell.     The  zoospores  are  uniciliate. 

Representing  the  Oochytrie^  is  an  interesting  fungus  first  fully 
investigated  by  Nowakowski,  namely,  Polyphagus  euglencE,  which 
attacks  the  cells  of  Euglena,  a  unicellular  animal.  Its  mycehum  con- 
sists of  a.  central  enlarged  portion  from  which  run  out  in  a  number  of 
directions  branches  which  end  in  extremely  fine  points  which  penetrate 
the  cells  of  Euglena.  The  enlarged  central  portion  develops  a  swollen 
tubular  outgrowth  into  which  its  protoplasm  wanders.  The  contents 
of  this  outgrowth  then  divide  into  numerous  uniciUate  swarm  spores 


Il8  MYCOLOGY 

which  escape  into  the  water.  Under  certain  conditions  a  cyst  appears 
in  place  of  a  zoosporangium.  This  is  thick-walled  and  of  a  yellow 
color  and  enters  a  period  of  rest.  After  the  rest  period,  the  membrane 
of  the  cyst  rupture  and  a  sporangium  appears.  Cysts  may  arise 
by  a  kind  of  sexual  union  where  two  unlike  mycelia  fuse  and  the 
protoplasm  of  both  flows  out  to  form  a  cyst  between  the  original  cells. 
Urophlyctis  pulposa  attacks  leaves  and  stems  of  Chenopodium  and 
A  triplex  species.  U.  alfalfcE  grows  in  the  roots  of  the  alfalfa  in 
South  America  and  Germany. 

Family  5.  Ancyclistace^. — This  is  a  small  family  consisting 
of  fungi  whose  mycelium  is  very  sHghtly  developed  and  not  easily 
distinguished  from  the  fruit  body.  In  one  subfamily  Lagenide^, 
the  mycelium  is  entirely  absent.  In  the  Ancycliste^,  there  is  a 
rich  development  of  the  mycelium  which  forms  lateral  tube-like 
branches,  which  penetrate  other  cells.  The  fruit  bodies  are  sac-hke 
and  give  rise  to  zoospores.  Sexual  organs  are  present  as  antheridia 
and  oogonia,  the  contents  of  the  former  passing  over  completely  into 
the  latter.  The  oospore,  which  is  formed,  is  found  free  in  the  oogonium. 
All  of  the  known  menxbers  of  this  family  are  endophytic  parasites  and 
the  different  stages  of  their  development  are  short-lived. 

Lagenidium  entophytum  lives  in  the  zygospores  of  species  of  Spiro- 
gyra.  L.  Rabenhorstii  parasitizes  the  cells  of  Spirogyra,  Mesocarpus, 
Mougeotia.  L.  pygmatim  lives  in  the  pollen  grains  of  diverse  species 
of  Pinus. 

BIBLIOGRAPHY  OF  OOMYCETALES 

Atkinson,  George  F.:  Damping  Off.  Bull  94,  Cornell  University  Agricultural 
Experiment  Station,  May,  1895;  Notes  on  the  Occurrence  of  Rhodochytrium 
spilanthidis  Lagerheim  in  North  America.  Science,  new  ser.,  xxviii:  691-692, 
Nov.  13,  1908;  Some  Fungus  Parasites  of  Algse.  Botanical  Gazette,  xlviii: 
321-338,  November,  1894. 

Clinton,  G.  P.:  Oospores  of  Potato  Blight,  PhytopMhora  hifeslans.  Report  Conn. 
Agricultural  Experiment  Station.  Part  x.  Biennial  Report  of  1909-1910: 
753~774;  Oospores  of  Potato  Blight.  Science,  new  ser.,  xxxiii:  744-747, 
May  12,  1911. 

Claxjssen,  p.:  Ueber  Eientwicklung  und  Befructung  bei  Saprolegnia,  monoica. 
Ber.  d.  Deut.  Bot.  Gesellsch.,  xxvi:  144,  1908. 

CoKER,  W.  C:  Another  New  Achlya.  Botanical^  Gazette,  50:  381-382,  November, 
1910. 

Davis,  Bradley  M.:  Cytological  Studies  on  Saprolegnia  and  Vaucheria.  The 
American  Naturalist,  xlii:  616-620. 


OOMYCETALES  II9 

DE  Bary,  a. :  Compaialixe  Morphology  and  Biology  of  the  Fungi,  Mycetozoa  and 

Bacteria,  1887:  132-145. 
DuGGAR,  Benjamin  M.:  Fungous  Diseases  of  Plants,  1909:  135-173. 
Engler,  Adolf,  and  Gilg,   Ernst:  Syllabus  der  Pflanzenfamilien,  7th   Edition, 

191 2:  38-42. 
Holder,   Chas.   F.  :  Methods  of   Combating   Fungous  Disease  on  Fishes.     Bull. 

of  the  Bureau  of  Fisheries,  xxviii:  935-936. 
Jones,  L.  R.,  Giddings,  N.  J.  and  Lutman,  B.  F.:  Investigations  of  the  Potato 

Fungus,  Phytophthora infestans.     Bull.  168,  Vermont  Agricultural  Experiment 

Station,  August,  191 2. 
Kerner,  Anton:  The  Natural  History  of  Plants,  1895,  ii:  668-672. 
Magnus,  P.:  Kurze  Bemerkung  iiber  Benennung  und  Verbreitung  der  Urophlyctis 

bohemica.     Centralblatt     f.    Bakteriologie,     Parasitunkunde     u.     infektions- 

krankhciten,  ix:  895-897,   1902;  Ueber    eine   neue   unterirdisch    lebende  Art 

der   Gattung  Urophlyctis.     Ber.  der  Deutschen  Bot.  Gesellschaft.,  xix:  145- 

153,  1901;  Ueber  die  in  den  KnoUigen  Wurzelanswuchsen  der  Luzerne  lebende 

Urophlyctis,  do.,  xx:  291-296,  1902;  Erkrankung  des  Rhabarbers  durch  Perono- 

spora  Jaapiana,  do.,  xxviii:  250-253,  1910. 
Melhus,  I.  E.:  Experiments  on  Spore  Germination  and  Infection  in  Certain  Species 

of  Oomycetes.     Research  Bull.   15,  Agricultural   Experiment    Station,    June, 

1911. 
MiYAKE,  K.:  The  Fertilization  of  Pythium  de  Baryanum.     Annals  of  Botany, 

xv:  653. 
Petersen,  Henning  E.:  An  Account  of  Danish  Fresh-water  Phycomycetes,  with 

Biological  and  Systematical  Remarks.     Annales  Mycologici,  viii:  494-560, 1910. 
RosENBAUM,  J.:  Studies  of  the  Genus  Phytophthora.     Jour.  Agric.  Res.  8:  233-276, 

with  pis.  7  and  key,  191 7. 
Spencer,  L.  B.:  Treatment  of  Fungus  on  Fishes  in  Captivity.     Bull.  Bureau  of 

Fisheries,  xxviii:  931-932,  1910. 
Stevens,  F.  L.:  The  Fungi  "Which  Cause  Plant  Disease,  1913:  66-101. 
Trone,  a.  H.:  On  the  Fertilization  of  Saprolegnieas.    Annals  of  Botany,  xviii:  541. 
VON  Tavel,  F.:  Vergleichende  Morphologic  der  Pilze,  1892:  5-25. 
Wager,  H.:  On  the  Fertilization  of  Peronospora  parasitica.     Annals  of  Botany, 

xiv:  263,  1900. 
Wettstein,  Richard  R.v.:  Handbuch  der  systematischen  Botanik,  191 1:  158-160. 
Wilson,  Guy  West:  Studies  in  North  American  Peronosporales  V.     A  Review  of  the 

Genus  Phytophthora.     Mycologia,  vi:  54-83,  March,  1914. 
ZiRZOW,  Paul:  A  New  Method  of  Combating   Fungus   on   Fishes   in   Captivity. 

Bull,  of  the  Bureau  of  Fisheries,  xxviii:  939-940,  1910. 
ZoPF,  Wilhelm:  Die  Pilze,  1890:  282-313. 
Wager-,  H.:  On  the  Structure  and  Reproduction  of   Cystopus  candidus.    Annals 

of  Botany,  x:  295,  1896. 


CHAPTER  XIV 

HIGHER  FUNGI 

SUBCLASS  MYCOMYCETES 

The  higher  true  fungi  are  characterized  by  a  mycelium  in  which  the 
hyphae,  as  a  rule,  are  permanently  multicellular  by  the  formation  of  trans- 
verse septa  dividing  the  hyphal  length  into  short  cells.  Some  mycolo- 
gists, among  them  Brefeld,  think  it  important  to  call  the  fungi  which 
are  transitional  between  the  Phycomycetes  and  the  Mycomycetes 
proper  by  the  name  MESOMYCETES,  but  the  distinction  between 
these  intermediate  forms  and  the  higher  fungi,  being  at  times  difficult 
to  make,  the  writer  has  thought  it  best  not  to  use  the  name  MESOMY- 
CETES, as  that  of  a  subclass.  The  student  will  see  the  justice  of  this 
viewpoint  as  the  discussion  proceeds. 

Of  unsatisfactory  position  in  the  fungous  system  are  two  families 
of  fungi,  which  Brefeld  includes  in  the  subclass  MESOMYCETES, 
which  will  illustrate  his  point  of  view  as  to  transitional  forms.  Under 
HEMIASCINEiE,  as  a  suborder,  he  includes  the  families  Ascoideace^e 
and  ProtomycetacEtE.  Engler  considers  that  these  families  have  a 
doubtful  systematic  position.  They  show  affinity  to  the  PHYCOMY- 
CETES, and  yet,  they  have  septate  hyphae  and  a  sporangium,  known 
as  an  ascus,  which  contains  an  indefinite  number  of  spores,  hence  their 
closer  affinity  to  the  fungi  of  the  order  ASCOMYCETALES.  The  first 
family  is  represented  by  Ascoidea  ruhescens  which  lives  on  wounded 
beech  tree  trunks,  particularly  in  the  sap  which  flows  from  the  wounds. 
It  forms  a  brown  felt-like  growth.  The  richly  septate  hyphae  cut  off 
laterally  and  terminally  conidiospores  and  sporangia  are  formed  in 
a  series,  so  that  as  the  numerous  derby-hat-shaped  spores  are  dis- 
charged and  the  sporangium  is  emptied  of  its  contents  a  new  sporangium 
forms  inside  of  the  walls  of  the  old  one,  so  that  ultimately  a  sporangium 
may  appear  to  arise  out  of  a  receptacle  with  a  wall  composed  of  three 
or  four  layers.  In  old  cultures,  the  fruit-bearing  hyphae  may  be  united 
to  form  Coremia.     The  genus  Dipodascus  belongs  to  this  family.     The 

I20 


HIGHER    FUNGI  121 

family  PROXOMYCETACE.f:;  is  represented  by  the  {genera  Prolotnyces, 
Monascus  and  Thclebolus.  Protomyccs  is  a  genus  of  fungi  parasitic 
in  the  higher  plants;  for  example,  P.  macrosporus  lives  in  Umbelli- 
FER^,  P.  pachydermus  in  Taraxacum.  The  coprophilous  fungus 
Thclebolus  stercoreus  lives  on  the  excrement  of  rabbits.  It  has  a  large 
rounded  sporangium  surrounded  by  a  cushion  of  hyphge.  Numerous 
spores  suggestive  of  the  moulds  are  formed  within  this  sporangium. 

ORDER  III.  ASCOMYCETALES.— The  fungi  of  this  order  are 
characterized  by  a  mycelium  which  lives  either  saprophytically,  or 
parasitically,  with  animals  or  plants.  It  has  with  few  exceptions  a 
rank,  or  exuberant,  development  sometimes  with  apical  growth.  The 
hyphae  are  septate  and  the  cells  are  uninucleate,  or  plurinucleate.  The 
reproduction  of  the  majority  of  species  is  through  endogenous  spores 
known  as  ascospores,  which  are  formed  in  definite  numbers,  usually 
eight,  sometimes  less  (four,  two,  one),  and  sometimes  more  (sixteen, 
thirty-two,  sixty-four,  etc.)  inside  of  a  sporangium  known  throughout 
the  order  as  an  ascus  (dcr/cos  =  wine-skin,  water  bottle).  Frequently, 
they  are  called  sac  fungi,  because  of  the  sac-like  ascus.  The  asci  are 
found  either  isolated,  or  more  generally,  they  are  in  fruit  bodies  where 
the  asci  are  usually  arranged  along  with  the  paraphyses  between  them 
in  definite  layers,  which  may  be  termed  ascigeral.  The  paraphyses 
may  assist  in  the  discharge  of  the  spores,  but  more  usually  their  func- 
tion is  that  of  packing  in  which  they  serve  also  for  the  protection  of 
the  adjacent  asci.  The  fruit  body  is  an  apothecium,  when  it  is  open 
with  the  ascigeral  layer  wholly  exposed.  Such  apothecia  may  be 
platter-like,  saucer-shaped,  cup-shaped,  or  goblet-shaped,  and  either 
sessile,  or  stalked,  the  length  of  the  stalks  being  a  variable  character. 
The  perithecium  is  a  closed  fruit  body  sometimes  produced  under 
ground  where  it  remains  subterranean.  It  may  be  entirely  closed  with 
no  opening  (cleistocarpous),  or  it  may  open  by  a  pore  at  the  top. 
This  pore  may  be  borne  directly  at  the  top  of  the  rounded  perithecium, 
or  the  perithecium  may  be  drawn  out  into  a  larger,  or  a  shorter  neck, 
so  that  it  becomes  flask-shaped,  or  bottle-like.  A  narrow  canal  may 
lead  through  the  neck,  which  may  be  straight,  or  variously  curved. 
Sometimes  the  paraphyses,  which  extend  through  the  neck  and  out 
of  the  pore,  are  designated  periphyses.  As  accessory  fruit  forms,  we 
find  the  conidiospores,  which  are  of  various  forms,  and  which  are 
borne  singly,  or  in  chains,  at  the  ends   of  vertical   hyphae  (conidio- 


122  MYCOLOGY 

phores),  or  they  are  inclosed  fruit  l)odies  willi  terminal  pores  known 
as  pycnidia   (pycnidium),  and  in  such  the  conidiospores  are  termed 
pycnidiospores,  or  pycnospores.     The  hyphae    also   break    up  into  a 
disconnected  series  of  spores  known  as  chlamydospores,  or  the  whole 
of  the  hypha  set  aside  for  reproductive  purposes  may  break  up  into  a 
connected  series  of  spores,  the  oidiospores.     Where  the  conidiophores 
are  united  together  into  strands,  a  coremium  is  formed.     Sclerotia, 
or  condensed  masses  of  resting  hyphae,  are  not  unusual  in  the  order. 
,  Certain  ascomycetous  fungi  are  lichen  fungi,  as  they  are  parasitic  on 
green  algae  and  with  them  form  the  lichen  thallus,  which  bears  a  certain 
nutritive  relation  with  the  organic  or  inorganic  substratum,  so  that 
we  may  distinguish  the  crustaceous,   foliose  and  fruticose  kinds  of 
Hchen  thalH.     Where  such  hchen  fungi  and  others  of  the  order  ASCOMY- 
CETALES  live  on  the  surface  of  bark,  they  are  epiphleoidal;  where 
beneath  the  surface,  hypophleoidal;  where  they  live  on  rock  surfaces, 
they  are  epilithic;  in  rock  holes,  hypolithic;  and  on  the  surface  of  the 
earth,  they  are  epigeic;  below  the  surface,  hypogeic.     The  growth  on 
the  surface  of  animals  is  ectozoic,  in  animals  endozoic.     The  growth  on 
the  surface  of  leaves  and  other  plant  parts  is  designated  epiphytic  or 
cpiphyllous;  inside  the  plant,  as  endophytic,  or  endophyllous.     Zoospores 
are  never  formed  in  any  of  the  fungi  of  the  order.     A  few  are  aquatic. 
That  sexuaHty  exists  in  forms  of  the  ASCOMYCETALES  has  been 
determined  only  recently  and  these  discoveries  confirm  the  views  of 
de  Bary,  who  claimed  that  the  process  existed  in  this  order,  although 
Brefeld  and  his  disciples  claimed  the  contrary.     Thanks  to  the  epoch- 
making  research  of  R.  A.  Harper,  seconded  by  that  of  Claussen,  J. 
P.  Lotsy,  Baur,  Darbishire,   Guillermond  and  others,  the  fact  that 
sexuality  exists  has  been  proven  indubitably.     The  first  type  displayed 
by  Pyronema,  Boudiera  and  related  genera  is  where  a  multinucleate 
carpogonium    with    a    trichogyne    is   fertilized    by    a    multinucleate 
antheridium.     A  uninucleate  antheridium  unites  with  a  uninucleate 
oogonium  in  the  Erysiphace^.     The  sexual  organs  are  more  or  less 
reduced  in  .many  genera  and  in  some  of   the   ASCOMYCETALES, 
they   are   wanting   completely.     In    the   development   of   the   sexual 
organs  and  in  the  behavior  of  the  egg-cell,  there  is  represented  here  a 
type  of  sexual  reproduction  which  has  its  closest  parallel  in  the  red 
algje  (RHODOPHYCEiE).     There  is  a  suggestive  similarity  between 
the  structure  of  the  sexual  organs  and  the  process  of  development 


HIGHER    FUNGI  1 23 

following  fecundation  in  SphcBrotheca,  Pyronema  and  Collcma,  and  in 
such  red  algae  as  Batr actios permum,  Nemalion  and  Dudresnaya.  A 
sketch  of  the  process  will  not  be  amiss.  The  antheridia  and  oogonia 
arise  in  Pyronema  from  the  apical  cells  of  thick  hyphal  branches, 
which  arise  vertically  from  the  substratum.  These  organs  stand  side 
by  side.  Soon  a  trichogyne  is  formed  on  the  oogonium,  as  a  papillar 
outgrowth,  and  subsequently  it  is  cut  off  from  the  oogonium  proper  by 
a  transverse  wall.  The  antheridium  and  oogonium  are  multinucleate 
from  the  start  and  a  broad  stalk  cell  is  cut  off  from  the  base  of  the 
oogonium.  The  tip  of  the  trichogyne  curves  over  to  meet  the  tips  of 
the  antheridium,  and  the  wall  between  them  is  dissolved  enough  to 
form  a  pore  by  which  the  cytoplasm  of  one  organ  becomes  continuous 
with  the  cytoplasm  of  the  trichogyne  in  which  the  nuclei  have  already 
disintegrated.  The  antheridial  nuclei  migrate  into  the  trichogyne,  and 
while  this  is  happening  the  nuclei  of  the  oogonium  move  to  the  center, 
where  they  become  collected  into  a  dense,  hollow  sphere.  Now  the 
basal  wall  of  the  trichogyne  breaks  down  and  the  antheridial  nuclei 
pass  into  the  oogonium  and  become  mingled  with  those  of  the  egg  cell. 
The  antheridia  and  carpogonial  nuclei  now  become  paired  without 
fusing.  Out  of  the  oogonium  grow  ascogenous  hyphae  and  the  paired 
nuclei  pass  into  them.  The  young  ascus  develops  from  a  penultimate 
cell  of  a  bent  ascogenous  hypha  with  two  nuclei  which  fuse,  after  the 
ascus  has  been  formed  and  this  fusion  represents  a  sexual  process.  The 
end  cell  of  the  ascogenous  hypha  and  the  stalk  cell  are  uninucleate, 
and  these  two  cells  may  fuse  to  form  a  binucleate  cell  out  of  which  a 
penultimate  cell  may  arise.  This  single  nucleus  of  the  ascus  then 
divides  to  form  the  series  of  eight  ascospores  usually  found  in  the  ascus. 
The  synapsis  stage  of  this  single  nucleus  is  immediately  followed  by  a 
reduction  division. 

Claussen^  has  found  that  the  formation  of  the  ascus  is  not  as  simple 
a  process,  as  described  by  Harper,  and  he  has  added  materially  to  our 
knowledge  by  his  reinvestigation  of  Pyronema  confluens  (Figs.  38,  39 
and  40).  He  finds  that  the  conjugate  nuclei  do  not  fuse  in  the  asco- 
gonium  (carpogonium),  nor  in  the  ascogenous  hyphae,  nor  in  the  pen- 
ultimate cell,  nor  when  the  tip  cell  of  the  ascogenous  hook  fuses  with 
the  stalk  cell  to  form  a  binucleate  cell.     He  finds  that  the  penultimate 

1  Claussen,  p.:  Zur  Entwickelungsgeschichte  der  Ascomyceten,  Pyronema  con- 
fluens.    Zeitscrift  fiir  Botanik,  4,  Jahrgang,  Heft:  1-64  with  6  plates. 


124 


MYCOLOGY 


cell  mav 


Fig.  38. — Diagrammatic  representation  of  the 
observed  methods  of  Ascus  formation.  {After 
Claussen,  Ziir  Enlivicklungsgeschicte  den  Ascomy- 
ceten,  Pyronema  conflucns,  Zeilschr.  fiir  Bolanik 
4  Jahrb.,  1912.) 


)enultiniatc,  Up  and  stalk  cells 
and  this  another,  and  during 
this  process  of  proliferation, 
the  nuclei  derived  by  descent 
from  the  antheridial  nuclei 
remain  distinct  from  those 
of  the  ascogonium  (carpogo- 
nium).  Even  the  two  nuclei 
derived  from  the  tip  and 
stalk  cells  show  this  dif- 
erence,  and  their  descendants 
remain  distinct  with  the  pro- 
liferation of  a  new  hook  with 
stalk  cell.  The  series  of  ac- 
companying figures  taken 
from  the  paper  by  P. 
Claussen  will  enable  the 
student  to  understand  the 
process  better  than  a  lengthy 
description. 

The  antheridia  and 
oogonia  of  Sph(Erothe.ca  arise 
as  lateral  branches  of  neigh- 
boring myceUai  filaments. 
The  oogonium  is  cut  off  from 
the  rest  of  the  hypha  by  a 
transverse  septa,  and  pos- 
sesses a  single  nucleus.  The 
antheridial  branch  appears 
quite  near  its  base  and  grows 
upward  pressed  closely  to  the 
side  of  the  oogonium.  The 
antheridial  cell  with  one 
nucleus  is  also  cut  off  by  a 
transverse  septum.  This 
nucleus  now  divides  and  one 
of  the  two  nuclei  passes  into 
the  attenuated  end  of    the 


HIGHER    FUNGI 


125 


antheridium,  which  is  cut  off  by  a  partition  wall.  The  walls 
between  the  two  organs  are  dissolved  and  the  male  nucleus  passes 
through  the  opening  formed  wanders  toward  the  egg  nucleus  with 
which  it  fuses.  Immediately  after  fertihzation,  the  oogonium  begins 
steady  growth,  and  some  of  the  outer  cells  formed  become  the  cover 


Fig.  39. — Diagrammatic    representation    of    the    development    of    the    ascogenous 
hyphal  system.      {After  Claussen.) 

cells  of  the  perithecium.  But  ascogenous  hyphae  are  formed,  which 
contain  two  nuclei,  then  four  nuclei  by  division  with  karyokinetic 
figures.  Two  of  the  nuclei  wander  to  the  curved  side  and  this  is  cut 
off  by  two  partition  walls  to  form  the  binucleated  penultimate  cell, 
which  becomes  the  mother  cell  of  the  ascus.     The  two  nuclei  of  the 


126 


MYCOLOGY 


ascus  now  unite.  The  fusion  or  nucleus  then  divides  to  form  those 
of  the  eight  ascospores,  and  the  walls  of  the  perithecium  grow  to  inclose 
the  asci  thus  formed,  including  the  paraphyses,  which  develop  between 
the  asci. 

All  of  the  typic  ASCOMYCETALES  have  uninucleate  hyphal  cells, 
while  the  ascogenous  hyphse  are  binucleate,  and  in  this  case  the  nucleus 
has  a  double  chromosome  number.  Hence  is  suggested  an  alternation 
of  generations. 

The  life  cycle  of  Pyronema  may  be  displayed  in  a  graphic  form 
beginning  with  the  ascospore  and  ending  with  its  production  again. 
The  diploid,  or  twenty-four  chromosome  condition,  may  be  repre- 
sented by  the  double  lines.  This  life  cycle  is  contrasted  with  the 
well-known  one  of  the  fern  where  a  well-marked  alternation  of  genera- 
tion is  shown. 


Fern 
Spore 


(After  Claussen) 


Pyronema 
Spore 


Prothalluim 

/      \ 

Antheridium      Archegonium 

I.  I 

Spermatozoid         Egg  cell 

I  I 


Mycelium 
Antheridium        Ascogonium 

I  1 

T.  i 

Antheridium        Ascogonium 


Sperm  nucleus  ^Egg  nucleus       (Sperm)  Nucleus     (Egg)  Nucleus 


\ 


/ 


Sporophyte 

il 

Spore  mother  cell 


4  Spores 


Ascogenous  hyphge 

h 

Uninucleate    ascus 


4  Nucleate  ascus 


Brown,  in  his  studies  of  Leotia,  has  shown  that  the  asci  are  formed 
at  the  tips  of  the  ascogenous  hyphae  in  several  different  ways  (Fig. 
41).     In  some  cases,  to  quote  him,  "a  hypha  forms  a  typical  hook, 


HIGHER    FUNGI 


127 


Fig    40. — Diagrammatic    representation    of    the    development    of    the    ascogenous 
hyphal  system  and  of  the  mature  ascus.      (After  Claiissen.) 


128 


MYCOLOGY 


Fig.  41. — 9,  Vegetative  hyphse  giving  rise  to  storage  cell;  10,  paraphyses  grow- 
ing out  from  storage  cells;  11-14,  fusion  of  nuclei  in  storage  cell;  15,  16,  nucleus  with 
two  nucleoli  in  storage  cell;  17,  large  storage  cell  with  single  very  large  nucleus;  18, 
storage  cell  with  very  irregularly  shaped  nucleus;  19,  storage  cell  containing  one 
large  and  two  small  nuclei;  20,  an  irregularly  shaped  storage  cell;  21,  22,  tip  of  as- 
cogenous  hypha  with  two  nuclei;  23,  two  nuclei  in  tip  of  hypha  have  divided  to  four; 
24,  walls  have  come  in,  separating  sister  nuclei;  25,  hook  in  which  there  is  no  wall 
cutting  off  uninucleate  ultimate  cell;  26,  hook  in  which  two  nviclei  have  fused  to 


HIGHER    FUNGI 


129 


consisting  of  a  binucleate  penultimate  and  a  uninucleate  ultimate  and 
antepenultimate  cell.  In  this  case,  the  two  nuclei  of  the  penultimate 
cell  may  fuse  to  form  the  nucleus  of-  an  ascus,  or  they  may  divide  and 
give  rise  to  four  nuclei  of  another  hook.  The  uninucleate  ultimate 
cell  usually  grows  down  and  fuses  with  the  antepenultimate  cell, 
after  which  the  nuclei  of  the  two  cells  may  give  rise  to  the  nuclei  of 
another  book  or  they  may  fuse  to  form  an  ascus.  The  walls  separating 
the  nuclei  may  fail  to  be  formed  without  affecting  the  fate  of  the  nuclei. 
In  this  process  there  is  a  conjugate  division  comparable  to  that  in  the 
rusts.  Frequently  the  ascogenous  hyphae- do  not  become  markedly 
bent,  and  in  this  case,  when  the  two  nuclei  in  the  tip  divide,  a  wall 
may  separate  two  pairs  of  sisters.  Either  of  these  pairs  may  divide 
and  give  rise  to  the  nuclei  of  another  hook  or  fuse  to  form  the  nucleus 
of  an  ascus.  Any  of  the  methods  described  above  by  which  the  number 
of  asci  is  increased  may  be  repeated  many  times.  Large  storage 
cells  are  formed  in  rows  which  give  rise  to  the  paraphyses.  They  are 
at  first  multinucleate  but  the  nuclei  fuse  as  growth  proceeds.  This 
process  continues  until  often  the  cells  contain  a  single  very  large  nucleus 
many  times  the  size  of  the  largest  nucleus  in  the  ascus.  The  nuclei 
are  very  irregular." 

Blackman,  V.  H.  AND  Fraser,  H.  C,  Jr.:  Fertilization  in  Sphjerotheca.     Annals 

of  Botany,  19:  567-569,  1905. 
Brown,  W.  H.  :  The  Development  of  the  Asocarp  of  Leotia.     Botanical  Gazette, 

50: 443-459- 
Claussen,    p.:  Zur    Entwickelung    der    Ascomyceten    Boudiera.     Bot.    Zeit.,    68 

(1905):  Zur  Entwickelungsgeschichte  der  Ascomyceten   Pyronema  confluens. 

Zeitschrift  fiir  Botanik,  4  Jahrgang,  Heft  i:  1-64;  Ueber  neuere  Arbeiten  zur 

Entwickelungsgeschichte  der  Ascomyceten.     Bar.  der.  deutsch.  Bot.  Gesellsch. 

Jahrg.,  1906,  Band  xxiv:  11-38  with  complete  bibliography. 
Engler,  A.  AND  GiLG,  Ernst.:  SyUabus  der  PflanzenfamiUen,  1912:  47. 


form  nucleus  of  ascus,  and  tip  has  fused  with  stalk  of  hook;  27,  ultimate  cell  has 
fused  with  antipenultimate;  nucleus  of  latter  has  migrated  into  former,  which  is 
growing  out  to  give  rise  to  ascus  or  another  hook;  28,  two  nuclei  of  penultimate  cell 
have  fused  to  form  nucleus  of  ascus;  ultimate  cell  has  fused  with  antepenultimate 
and  nucleus  of  latter  has  migrated  into  former,  which  has  grown  out  to  form  another 
hook;  29,  bmucleate  penultimate  cell  has  given  rise  to  hook;  ultimate  cell  has  fused 
with  penultimate,  and  the  two  nuclei  have  fused;  ultimate  cell  has  not  developed 
further;  30,  binucleate  penultimate  cell  has  formed  ascus,  which  fusion  product  of 
ultimate  and  antepenultimate  has  given  rise  to  second  ascus;  31,  diagram  illustrating 
multiplication  of  number  of  asci  by  method  shown  in  26-30;  9-20  Xr400.  21-30  X 
2100.  (Aftey  Brown.  William  H.,  The  Development  of  the  Ascocarp  of  Leotia.  Botanical 
Gazette,  50:  443-359,  Dec,  1910.) 
9 


I30  MYCOLOGY 

Fraser,  H.  C.  J.  AND  Welsford,  E.  T.:  Further  Contributions  to  the  Cytology  of 
the  Ascomycetes.     Annals  of  Botany,  xxii  (1908). 

GuiLLERMOND,  A.:  La  quest,  d.l.  sex  chez.  1.  Asc.  et  les.  rec.  trav.  Rev.  gen.  de 
Bot.,  XX  (1908):  Recherches  Cytologique  Taxonomique  sur  les  Endomycetes. 
Rev.  gen.  de  Bot.,  21:  353-39;  401-419  (1909)  and  a  number  of  papers  on  the 
same  subject  in  vol.  20. 

Harper,  Robert  A.:  Die  Entwicklung  der  Peritheciums  bei  Sphasrotheca  Cast- 
agnei,  Ber.  d.  Deutsch.  Bot.  Gesellsch.,  13:  475-1895;  Kerntheilung  und 
freie  Zellbildung  in  Ascus  Jahrb.  f.  wiss.  Bot.,  30:  249-284,  1897;  Cell  Division 
in  Sporangia  and  Asci.  Annals  of  Botany,  13:  467-524,  1899;  Sexual  Repro- 
duction in  Pyronema  confluens  and  the  Morphology  of  the  Ascocarp.  Annals 
of  Botany,  14:  321-400,  1900. 

MoTTiER,  David  M.:  Fecundation  in  Plants.  Publ.  51,  Carnegie  Institution  of 
Washington,  1904. 

Sands,  M.  C:  Nuclear  Structure  and  Spore  Formation  in  Microsphasra  alni. 
Trans.  Wise.  Acad.  Sci.,  15;  733-752;  Botanical  Gazette,  46:79. 

Ward,  H.  Marshall::  P'ungi,  Encyclopedia  Britannica,  nth  Edition. 

Wettstein,  Richard  R.v.:  Handbuch  der  systematischen  Botanik,  1911:  169-172 


CHAPTER  XV 
SAC  FUNGI  IN  PARTICULAR  (YEASTS,  ETC.) 

Suborder  A.  Protoasciineae.— The  fungi  of  this  suborder  are  charac- 
terized by  the  absence  of  definite  fruit  bodies,  that  is  the  asci  are  not 
enclosed,  but  are  free  and  at  the  ends  of  hyphae.  Usually  they  are  of 
unequal  length.  Four  is  the  typical  number  of  ascospores  in  each 
ascus.     These  are  one-celled  and  may  increase  in  number  by  gemmation. 

Family  i.  Endomycetace^. — This  family  is  a  small  one  of  four 
genera  of  saprophytes  and  parasites.  The  two  species  of  the  genus 
Podocapsa  are  parasitic  on  Mucorace^,  Eremascus  albus,  the  single 
species  of  that  genus  grows  on  spoilt  malt  extract.  The  genus  En- 
domyces  with  five  species  is  represented  by  the  cosmopolitan  Endo- 
myces  decipiens,  which  forms  a  snow-white  parasitic  growth  on  the 
toadstool  Armillaria  meltea.  Its  hyphae  are  branched  richly  and  the 
asci  are  pear-shaped  and  borne  singly  at  the  ends  of  the  branches, 
each  producing  four  helmet-shaped  ascospores,  6  to  S/jl  broad  and  s^u 
high.  Conidiospores  are  more  frequently  foimed  than  ascospores. 
Oidiospores  are  also  found,  as  well,  as  chlamydospores.  Oleina  nodosa 
and  O.  lateralis  are  the  two  species  of  the  fourth  genus.  The  first 
grows  in  ohve  oil. 

Family  2.  ExoASCACEifc.— This  family  includes  parasitic  fungi 
which  cause  abnormalities  of  more  or  less  marked  character  of  the 
leaves,  fruits  and  branches  of  mostly  woody  plants.  The  malforma- 
tions are  in  the  nature  of  witches'  brooms  of  the  smaller  branches, 
leaf  curls,  and  deformed  fruits,  such  as  the  plum  pocket.  Stone  fruits 
are  especially  subject  to  attack  and  in  some  cases  the  stone  formation 
is  suppressed  entirely.  The  myceUum  may  be  deep-seated  and 
perennial,  or  it  may  be  subcuticular,  or  sometimes  found  growing 
between  the  epidermal  cells,  as  in  Magnusiella  flava,  while  in  other 
forms,  the  hyphae  may  be  below  the  epidermis  and  grow  throughout 
the  leaf  tissue.  The  asci  are  generally  formed  on  the  surface  of  the 
host  breaking  through  from  the  more  deep-seated  mycehum  beneath. 
They  are  generally  stalkless  and  arranged  in  close  proximity  to  each 

131 


132 


MYCOLOGY 


other  without  paraphyses,  so  that  they  form  a  velvety  layer  on  the 
surface  of  the  host  plant.  Eight  ascospores  are  generally  found,  as  in 
the  genus  Exoascus,  but  in  Taphr'ma  (Taphria)  the  number  may  be 
increased  considerably  by  budding,  so  that  the  whole  ascus  will  be 


-::#\ 


■^h 


y     ,  ,;  ff 


^^^  ^rrf^f 


Fig.  42. — Exoascus  and  Taphrina.  A-F,  Exoascus  pruni,  A.  Appearance  on 
diseased  twig;  B,  cross-section  of  diseased  fruit;  C,  mycelium  in  tissues  of  host;  D, 
young  asci;  E,  mature  ascus  with  spores;  F,  germination  of  spores;  G,  E,  Exoascus 
alnitorquus;  H,  Taphrina  aurea,  ripe  and  unripe  asci;  J,  Taphrina  Sadebeckii.  See 
Die  naturlichen  Pflanzenfamilien  I.  i,  p.  159. 


crammed  full  of  them  (Fig.  42).     The  ascospores  are  generally  ellip- 
soidal and  always  one-celled  with  colorless,  yellow,  or  orange  contents. 
The  perennial  mycelium  is  responsible  for  the  formation  of  witches' 
brooms  in  a  variety  of  trees  and  woody  plants.     Most  of  them  are  the 


SAC   FUNGI   IN   PARTICULAR  -  1 33 

result  of  the  parasitism  of  species  of  Exoascus.  The  "hexenbesen" 
are  brush-Uke,  or  tufted  masses  of  branches,  which  suggest  the  presence 
of  other  plants  (Uke  the  mistletoe)  parasitically  or  epiphytically 
growing.  They  result  mainly  by  the  infection  of  a  bud  which  de- 
velops a  branch  with  increased  growth.  On  this  branch,  all  dormant 
buds  are  stimulated  to  activity  and  the  whole  infected  system  of 
branches  consists  of  negatively  geotropic  branches.  These  brush- 
like excrescences  are  called  the  thunder-bushes,  and  are -sometimes 
nest-like  in  appearance.  An  anatomic  study  shows  that  the  parenchy- 
matous tissues — pith,  hypodermis,  etc. — are  greatly  increased;  wood 
and  bark  are  traversed  by  abnormally  broad  medullary  rays,  the  ducts 
have  short  members,  the  wood  fibers  wide  lumina,  which  are  sometimes 
thin-walled  and  septate.  The  bast  fibers  are  few,  or  entirely  wanting. 
The  cork  cells  are  enlarged  and  retain  their  protoplasmic  contents  a 
longer  time.  The  form  of  the  witches'  brooms  are  various.  Many 
of  them  are  pendent,  some  are  nest-like,  owing  to  the  death  of  some  of 
the  branches.  In  some  the  branches  are  elongated,  while  some  have 
short  twigs.  The  end  of  the  original  branch  from  which  the  lateral 
branches  developed  usually  dies  and  its  food  substances  are  absorbed 
by  the  hypertrophied  branches.  The  family  includes  three  genera, 
distinguished,  as  follows: 

A.  Asci  found  at  the  end  of  intercellular  mycelial  branches. 

I.  Magnusiella. 

B.  Asci  developed  on  a  more  or  less  subcuticular  ascogenous  mycel- 
ium. 

(o)  Asci  eight-  (exceptionally  four-)  spored.  2.  Exoascus. 

ib)  Asci  many-spored  by  gemmation  of  the  spores.         3.  Taphrina. 

The  genus  Magnusiella  comprises  five  species,  four  of  which  are  found 
in  Europe  and  two  in  America.  Magnusiella  flava  forms  small  pale 
yellow  specks  on  the  leaves  of  the  gray  birch,  Betula  populifolia  in 
North  America.  The  genus  Exoascus  includes  about  thirty  species 
arranged  in  two  subgenera,  the  first  of  which  includes  those  species  which 
deform  fruits,  which  form  witches'  brooms,  and  the  second  those  which 
cause  a  spotting  of  the  leaves  of  various  plants.  It  would  lengthen 
this  book  unduly  to  enumerate  all  of  the  species  of  Exoascus  with  an 
account  of  the  deformities  of  branches  and  fruits  which  they  produce. 
Only  a  few  of  the  more  important  species  will  be  enumerated  here, 


134 


MYCOLOGY 


and  the  diseases  which  they  cause  will  be  described  later.  Exoascus 
pruni  (Fig.  42)  is  the  cause  of  an  important  disease  of  plum  trees, 
producing  the  so-called  plum  pockets.  It  also  attacks  Pruniis  domestica 
and  P.  padus  in  middle  Europe,  and  P.  domestica  and  P.  virginiana  in 
North  America.  Exoascus  communis  attacks  the  fruits  of  several 
American  species  of  Prunus  among  them  P.  maritima.  Exoascus 
alnitorquus  infests  the  pistillate  spikes  and  cones  of  species  of  alder 
(Alnus),  such  as  Alnus  glutinosa  and  A.  incana  in  middle  Europe,  and 
A.  incana  and  A.  rubra  in  North  America,  causing  an  enlargement  of 
the  fruit  scales  into  twisted,  tongue-like,  reddish  outgrowths.  Exoascus 
deformans  is  the  cause  of  peach-leaf  curl.  Exoascus  cerasi  is  responsible 
for  the  formation  of  witches'  brooms  on  the  cherry.  The  genus 
Taphrina  causes  witches'  brooms  and  leaf  spots.  Taphrina  purpuras- 
cens  attacks  the  leaves  of  a  North  American  sumac,  Rhus  copallina, 
causing  a  puckering  of  the  leaves  with  the  formation  of  a  reddish- 
purple  color.  T.  aurea  (Fig.  42)  forms  yellow  blotches  on  the  leaves  of 
several  European  and  North  American  poplars,  viz.,  Populus  nigra  and 
P.  italica  of  Europe,  and  P.  Fremontii,  P.  grandidentata  and  P.  deltoides 
of  North  America.  T.  Laurencia  causes  witches'  brooms  on  a  fern  in 
Ceylon,  Pteris  quadriaurita. 

Suborder  B.  Saccharomycetiineae. — A  true  filamentous  mycelium 
is  absent  in  the  fungi  of  this  suborder.  The  plants  are  single-celled 
and  reproduce  by  budding,  or  gemmation.  Occasionally  under  ex- 
perimental treatment  where  the  culture  media  are  varied,  the  cells 
develop  into  hyphae  and  together  form  a  myceHoid  growth.  Spore 
formation  consists  in  a  single  cell,  developing  one  to  eight  spores. 
It,  therefore,  may  be  looked  upon  as  an  ascus  and  the  spores  are  as- 
cospores.     Many  of  them  cause  fermentation. 

Family  i.  Saccharomycetace^. — Many  species  of  the  genus 
Saccharomyces  are  called  generically  yeasts,  and  are  of  economic 
importance,  because  they  induce  the  alcoholic  fermentation  of  car- 
bohydrate substances.  The  action  is  accompl  shed  through  a  soluble 
enzyme  formed  in  the  protoplasm  of  the  yeast  cell,  and  first  isolated 
by  Buchner  by  grinding  the  yeast  cells  in  sand  and  extracting  the 
ferment  zymase.  The  general  shape  of  yeast  cells  is  oval,  ellipsoidal, 
and  pyriform  (Figs.  43,  44).  The  cell  wall  is  well  defined  and  consists 
of  modified  forms  of  cellulose  which  may  be  called  fungous  cellulose, 
because  it  does  not  react  to  the  reagents  used  for  true  cellulose.     This 


SAC   FUNGI   IN   PARTICULAR 


135 


much  can  be  said  that  the  wall  consists  of  a  carbohydrate,  probably 
some  isomer  of  cellulose.  Lining  the  inner  surface  of  the  cell  wall  is  a 
layer  of  protoplasm  which  may  be  called  the  ectoplasm,  which  probably 
serves  as  an  osmotic  membrane.  The  cytoplasm  fills  the  rest  of  the  cell 
with  the  exception  of  spaces  occupied  by  the  vacuoles  of  glycogen, 
nuclear  vacuoles,  oil  globules,  the  nucleus  and  nuclear  granules.  The 
glycogen  is  gradually  used  up  as  it  probably  serves  as  reserve  food, 
the  same  as  starch  in  the  higher  plants.  These  glycogen  vacuoles 
generally  coalesce  until  one  large  vacuole  may  almost  fill  the  cell. 


J 

6         7       8       12 

Fig.  43.  Fig.  44. 

Fig.   43. — Yeast  cell,  Saccharomyces  cerevisicB.      {After  Marshall.) 
Fig.  44. — Yeast,    Saccharomyces    cerevisicB.      i-io.    Young    cells    with    nucleus, 
showing  its  structure;  6-8,  division  of  nucleus;  11-13,  cells  after  twenty-four  hours" 
fermentation  with  large  glycogenic  vacuole  filled  with  lightly  colored  grains.      {After 
Marshall,  Microbiology,  Second  edition,  p.  62.) 

the  cytoplasm  and  nuclear  bodies  being  pressed  against  the  cell  wall 
and  forming  a  thin  protoplasmic  hning  to  the  inner  cell  wall  surface. 
Wager  1  in  1898  demonstrated  the  nuclear  apparatus  in  a  number  of 
yeast  species.  The  nuclear  apparatus  consists  in  the  earliest  stages  of 
fermentation  of  a  nucleolus  in  close  touch  with  a  vacuole  (Fig.  44,  No.  4) 
which  includes  a  granular  chromatin  network  suggesting  a  similar  struc- 
ture in  the  higher  plants.  The  vacuole  may  disappear  and  then  the 
chromatin  granules  are  scattered  through  the  protoplasm,  or  are  gathered 
around  the  nucleolus,  which  is  present  in  all  of  the  cells,  as  a  perfectly 
homogeneous  body.     Numerous  chromatin  vacuoles  are  often  found 

1  Wager,  Harold:  The  Nucleus  of  the  Yeast  Plant.     The  Annals  of  Botany 
.xii:  400-539- 


136 


MYCOLOGY 


in  young  cells  and  these  ultimately  fuse  to  form  a  single  vacuole  which 
occurs  in  the  cells  during  the  earher  and  the  later  fermentation.  The 
process  of  budding  is  associated  with  the  stretching  of  a  network  of  nu- 
clear granules  and  its  final  constriction  in  the  neck  between  the  mother 
and  the  daughter  cell.  The  nucleolus  moves  to  the  constriction  where 
it  becomes  dumbbell- 
shaped,  one  half  press- 
ing into  the  daughter 
cell  (Figs.  44  and  45). 
There  are  no  stages  of 
karyokinesis  dis- 
played, but  by  the  sim-  w^  f  1,«k  W  /<^ 
pie  process  described  ^^  -"^  ^^^  ^  ^^ 
above  the  daughter 
cell  receives  approxi- 
mately one-half  of  the 
nuclear    substance    of 


r^ 


^ 


y^^r. 


Fig.  45.  Fig.  46. 

Fig.  45. — Young  yeast  cells,  Saccharomyces  ellipsoideus,  with  nuclei  and  division 
of  nuclei.      (After  Marshall,  Microbiology,  Second  edition,  p.  64.) 

Fig.  46. — Yeast,  Saccharomyces  cerevisice,  the  variety  known  as  brewers'  bottom 
yeast;  a,  spore  formation;  h,  elongated  cells.  {After  Schneider,  Pharmaceutical  Bac- 
teriology, p.  144.) 

the  mother  cell.  In  spore  formation,  the  chromation  which  is  scattered 
through  the  cytoplasm  is  absorbed  more  or  less  completely  into  the 
nucleolus  which  elongates  and  divides  by  a  constriction  in  its  middle 
part.  Subsequent  divisions  result  in  the  formation  of  four  nucleoli 
around  which  protoplasm  collects  and  thin  membranes  which  become 
the  walls  of  the  ascospores  which  remain  at  first  small,  but  later  increase 
in  size  (Fig.  46).     The  formation  of  spores  can  be  secured  by  taking 


Q^^ 


SAC   FUNGI  IN   PARTICULAR  137 

a  Sterile  block  of  plaster  of  Paris  with  a  saucer-shaped  hollow  on 
top.  This  block  is  placed  in  sterilized  water  and  the  top  is  seeded 
with  vigorous,  young  well-nourished  yeast  plants  which  develop  spores 
if  kept  at  25°C.,  in  from  twenty-four  to  forty-eight  hours.  The  tem- 
perature at  which  spore  formation  occurs  and  the  time  which  it  takes 
for  sporulation  are  points  which  have  been  obtained  by  experimenta- 
tion for  all  the  more  important  species  of  yeasts.  The  data  which  has 
been  obtained  is  used  in  the  physiologic  diagnosis,  or  identification  of 
the  various  kinds  of  Saccharomycetace^,  which  react  differently 
under  experimental  treatment.  Film  formation  is  also  of  diagnostic 
importance,  where  economic  yeasts  form  floating  films  on  the  nutrient 
liquid  media  in  which  they  are  grown.  The  time 
required  for  the  development  of  the  film  differs,  /^ 
other  conditions  being  equal,  with  the  species  of  ^^  r^\^(^ 
the  yeast  and  is  longer  the  lower  the  temperature 
of  the  culture.  Hansen  obtained  the  following  data 
for  Saccharomyces  cerevisicB ; 

Film  formation  takes  place  at: 

S3°  to  34°C.  in  about    9  to  18  days.  ^    ^/^-    47-— Yeast. 

o  i     "  no,-^    •       .       ^        i  1  Saccharomyces  cerevi. 

20    to  28  C.  in  about    7  to  11  days.  ,-^_    growing    repro- 

13°  to  I5°C.  in  about  15  to  30  days.  duction  by  germina- 

6°  to  7o°C.  in  about    2  to    3  months.  tion,   or  budding;  a, 

single  cells;    b,    bud- 

No  formation  of  film  occurred  above  34°C.  or  below  ding  cells.  {After 
5°C.  Another  point  of  importance  is  that  species  ^IZiJ^X'^'^J'' 
of  Saccharomyces  form  films  so  that  this  process  is 
not  entirely  associated  with  the  fungi  belonging  to  the  so-called  genus 
Mycoderma.  In  fact  some  authors  recognizing  that  Saccharomyces 
cerevisicB  (Fig.  47)  produced  films  have  named  that  yeast,  Mycoderma 
cerevisicB,  and  have  thus  confused  its  identity. 

Hansen  in  a  paper  published  in  1888  classified  the  yeasts  essentially, 
as  follows: 

1.  Species  which  ferment  dextrose,  maltose,  saccharose:  Saccharo- 
myces cerevisicB  I,  S.  Pastorianus  I,  S.  Pastoriamis  II,  S.  Pastorianus 
III,  S.  ellipsoideus  I,  S.  ellipsoideus  II. 

2.  Species  which  ferment  dextrose  and  saccharose,  but  not  maltose: 
Saccharomyces  Marxianus,  S.  exiguus,  S.  Ludwigii  S.  saturnus. 

3.  Species  which  ferment  dextrose,  but  neither  saccharose  nor 
maltose:  Saccharomyces  mali  Duclauxii. 


138  MYCOLOGY 

4.  Species  which  ferment  dextrose  and  maltose,  but  not  saccharose 
Saccharomyces  n.  sp.  obtained  from  stomach  of  bee  by  Klocker. 

5.  Species  which  ferment  neither  maltose,  dextrose  nor  saccharose: 
Saccharomyces  anomalus  var  belgicus,  S.  farinosus,  S.  hyalosporus,  S. 
memhranifaciens. 

The  general  chemic  phenomena  associated  with  the  formation  of 
alcohol  by  fermentation  out  of  sugar  may  be  expressed  by  the  formula: 

CeHioOe  =  2C2H6O  +  2CO2 

Alcohol  Carbon 

dioxide 

The  carbon  dioxide  passes  off  in  bubbles  as  a  gas,  while  the  alcohol 
remains  in  solution. 

The  most  important  yeast  is  the  beer  yeast  Saccharomyces  cerevi- 
sicB  which  is  a  unicellular  plant  of  spheric  or  elliptic  shape  8  to  12/1 
long  and  8  to  10//  broad.  Sometimes  the  cells  formed  by  budding 
remain  connected  to  form  a  chain  consisting  of  the  mother,  daughter, 
granddaughter  and  great-granddaughter  cells.  Spore  formation  is 
characteristic  and  the  size  of  the  spores  varies  from  2.5  to  6/i.  There 
are  usually  four  spores  in  each  cell.  The  following  gives  the  tempera- 
ture conditions  of  spore  formation  in  this  species: 

At    9°C.  no  spores  develop. 

At  11°  to  i2°C.  the  first  indications  are  seen  after  10  days. 

At  3o°C.  the  first  indications  are  seen  after  20  hours. 

At  36°  to  37°C.  the  first  indications  are  seen  after  29  hours. 

At  37.S°C.  no  spores  develop. 

The  temperature  limits  for  film  formation  are  33°  to  34°C.  and  6° 
to  7°C.  There  are  a  number  of  races  of  the  common  beer  yeast,  which 
may  be  separated  into  the  bottom  yeasts  and  the  top  yeasts.  The  bot- 
tom yeasts  are  those  which  live  within  the  hquid  and  mostly  at  the 
bottom  even  from  the  start.  Some  of  these  yeasts  form  spores  with 
difficulty.  The  top  fermentation  yeasts  are  those  which  grow  on  the 
surface  of  the  liquid  and  cause  a  brisk'fermentation  with  a  large  amount 
of  froth,  or  head,  as  exemplified  by  the  Munich  lager-beer  yeasts. 
Yeasts  are  among  the  oldest  of  cultivated  plants,  as  in  biblical  times 
leavened  (yeast-raised)  and  unleavened  bread  were  known.  The 
leaven  was  a  lump  of  dough  kept  from  one  baking  to  the  next.  Un- 
leavened bread  was  simply  flour  mixed  with  water  and  baked,  and  as 
a  result,  a  hard  tough  bread  was  obtained.     The  .use  of  yeast  as  a 


SAC   FUNGI   IN   PARTICULAR 


39 


Starter  began  in  Roman  times,  but  the  art  was  lost  until  the  seventeenth 
century,  when  it  was  regained.  One  of  the  earliest  methods  of  obtain- 
ing yeast  was  salt  raising,  which  consisted  in  adding  to  a  quantity  of 
milk  a  little  salt  sufficient  to  delay  the  growth  of  bacteria,  while  the 
yeast  found  entrance  to  the  milk  through  the  air  and  grew  rapidly. 
This  milk  was  then  mixed  with  dough  for  the  raising  process.  Bakers 
also  sometimes  used  a  brew  called  barms.  Scotch  barms  were  prepared 
by  taking  hops  and  flour  with  other  ingredients  which  were  allowed  to 


^    '^^   ^   ^^^ 
C^^^ 


Fig.  48. — Saccharomyces  ellipsoideus.  A  common  yeast  in  jams,  jellies,  etc. 
Budding  process  is  shown  in  many  of  the  cells  as  also  the  vacuoles.  Fig.  66,  p.  145, 
Schneider,  Pharmaceutical  Bacteriology,  1912. 


ferment    spontaneously,    and    the    fermented    material   was    used    in 
bread  baking  (see  page  667). 

Saccharomyces  ellipsoideus  (Fig.  48)  is  known  as  the  wine  yeast  and 
may  be  classed  as  a  wild  species,  while  the  beer  yeast  is  found  only  in 
cultivation.  The  vegetative  cells  are  ellipsoidal  6/x  long,  single,  or 
united  into  a  row  of  loosely  connected  cells.  The  cells  are  two-  to  four- 
spored.  The  spores  are  spheric  2  to  4/i  broad.  It  is  important  in  the 
fermentation  of  grape  juice,  gaining  entrance  from  the  skin  of  the 
grape  fruit  upon  which  it  lives.  In  the  spore  form,  it  overwinters  in 
the  soil,  being  blown  as  dust  to  the  developing  grape  fruits.     The 


I40  MYCOLOGY 

bouquet,  or  flavor  of  the  wine  seems  to  be  clue  to  the  variety  of  wine 
yeast  used  in  the  fermentation  of  the  juice,  for  every  wine-producing 
region  seems  to  have  its  especial  form  of  wine  yeast  and  the  growth  is 
different.  Some  yeasts,  such  as  those  of  Burgundy  and  Champagne, 
form  a  compact  sediment,  which  quickly  settles  leaving  the  liquid 
clear,  while  others  remain  for  a  long  time  suspended  and  settle  slowly. 
Saccharomyces  ellipsoideus  II  is  a  very  dangerous  disease  yeast,  produc- 
ing turbidity  in  the  liquid  of  bottom  fermentation  breweries. 

Saccharomyces  Pastorianus  I  was  first  discovered  in  the  dust  of  a 
Copenhagen  brewery  and  also  in  diseased  beer.  Its  growth  in  wort 
consists  of  sausage-shaped  cells.  S.  Pastorianus  II  produces  a  feeble 
top  fermentation.  S.  Pastorianus  III  was  found  in  bottom  fermenta- 
tion beer  affected  with  yeast  turbidity. 

Saccharomyces  ilicis  and  5.  aquiJolU  were  found  on  the  fruits  of  the 
holly,  Ilex  aquifolium. 

Saccharom,yces  Vordemanni  is  similar  in  appearance  to  wine  yeast, 
its  cells  being  onion-shaped,  or  pear-shaped.  It  is  present  in  Raggi, 
which  is  employed  in  Java  in  the  manufacture  of  arrack.  It  forms  9 
to  10  per  cent,  alcohol. 

Saccharomyces  pyriformis  was  discovered  by  H.  Marshall  Ward  to  be 
active  in  the  formation  of  ginger  beer  in  conjunction  with  Bacterium 
vermiforme,  for  when  these  organisms  are  added  to  a  sugar  solution 
containing  ginger,  an  acid  beverage  with  considerable  head  is  formed 
known  as  ginger  beer. 

Saccharomyces  exiguus  occurs  in  pressed  yeast,  and  it  is  capable  of 
developing  considerable  alcohol  from  dextrose  and  saccharose  solutions. 
Saccharomyces  anomalus  has  been  found  in  impure  brewery  yeast 
in  Hungary,  also  in  Belgian  beer,  on  green  malt,  on  bran,  in  syrup  of 
Althaea,  in  soil,  and  on  plum  fruits.  It  ferments  wort  readily  forming 
a  gray  film,  a  turbidity  in  the  liquid,  and  an  odor  like  fruit  ether. 
The  spores  are  helmet-shaped,  suggesting  those  of  Endomyces  decipiens, 
which  is  parasitic  on  the  caps  of  A  rmillaria  mellea,  a  toadstool.  Saccha- 
romyces memhranifaciens  grows  in  a  gelatinous  mass  on  the  injured  roots 
of  elm  trees,  in  polluted  water,  and  in  white  wines,  where'it  destroys  the 
bouquet  of  the  wine.  It  completely  consumes  acetic  and  succinic 
acids,  and  quickly  forms  gray  corrugated  films  on  the  surface  of  wort. 
The  organisms  of  Kefir  are  Saccharomyces  cartilaginosus  and  S.  fragilis. 
Kefir  is  a  beverage  prepared  originally  in  the  Caucasus  region  by  fer- 


SAC    FUNGI   IN   PARTICULAR 


141 


menting  milk.  Kefir  grains,  which  include  the  above  yeasts,  a  Torula, 
and  3  bacteria  {Bacillus  caucasicus,  etc.)  are  added  to  the  milk  as  a 
starter.  The  fermentation  of  the  milk  results  in  the  formation  of  alcohol 
lactic  acid  and  carbonic  acid.  Mazum  (Matzoon)  an  Armenian  drink, 
is  prepared  by  adding  a  white,  fatty  cheese-like  mass,  to  milk.  The 
starter  includes  colored  yeasts  Oidium  laclis,  mould  fungi,  a  yellow 
Sarcina,  Bacillus  subtilis,  some  cocci.  Bacterium  acidilactici  a.nd  Saccharo- 
niyces  anomalus.  The  only  species  of  yeast,  which  can  be  recognized 
immediately  by  microscopic  examination,  is  Saccharomyces  Ludwigii, 
with  its  lemon-shaped  vegetative  cells,  on  the  point  of  which  a  wart 
makes  its  appearance,  which  is  cut  off  by  a  septum  from  the  rest  of  the 
cell.  This  species  is  transitional  to  those  included  in  the  genus  Schizo- 
saccharomyces.  The  form  of  Saccharomyces  Ludwigii  suggests  S. 
apiculatus,  which  is  unequally  dumbbell-shaped.  The  genus  Tonda 
according  to  Hansen  includes  yeasts  similar  to  Saccharomyces,  but 
which  do  not  form  endospores,  a  typical  mould  growth,  and  which 
produce  alcohol  in  all  percentages.  They  are  widely  distributed  in 
nature. 

Schroter  in  Engler's  "Die  naturlichen  Pflanzenfamihen"  recognizes 
only  two  genera  in  the  yeast  family,  namely,  Saccharomyces  and  Mono- 
spora.  The  reproductive  cells  of  the  former  have  two  to  eight  (seldom 
one  to  three)  spores  and  the  spores  are  spheric,  or  ellipsoidal,  while  the 
needle-shaped  spores  of  Monospora  are  borne  singly  in  reproductive 
cells,  or  asci.  Hansen^  considers  Monospora  to  be  a  doubtful  form  of 
yeast  {Saccharomyces  douteux),  as  also  the  genus  Nematospora.  He 
recognizes  the  following  genera:  Saccharomyces,  whose  spores  have  a 
single  membrane  and  the  cells  reproduce  hyhxiddrng;  Zygosaccharomyces, 
where  the  asci  are  associated  with  conjugation;  Saccharomycodes,  whose 
spores  have  one  membrane  and  sprout  into  a  promycelium;  Saccharo- 
mycopsis,  whose  spores  have  two  membranes;  Pichia  with  hemispheric 
or  angular  spores  and  Villia  with  citron-shaped  spores.  Lafar  in  his 
book  on  "Technical  Mycology"  (II,  part  2,  page  274)  gives  an  analytic 
summary  of  the  genera  which  he  believes  should  be  recognized.  The 
position  of  such  genera  as  Zygosaccharomyces,  Saccharomycopsis, 
Schizosaccharomyces  with  respect  to  nearly  related  fungi  is  presented 
and    discussed   with    a    diagrammatic    scheme    of    relationship     by 

^  Hansen,  E.  Chr.:  Grundlinien  zur  Systematik  der  Saccharomyceten.     Centr. 
f.  Bak.,  1904. 


142  MYCOLOGY 

Guillermond/  who  suggests  the  probable  evolution  of  such  forms  from 
Eretnascus  and  Endomyces.  Dr.  H.  Will  discusses  in  Lafar's  book 
the  family  Torulace^e,  species  of  which  are  widely  disseminated  on 
field  and  garden  fruits  and  on  plants  of  all  kinds  finding  suitable  condi- 
tions for  their  growth  during  the  decay  of  these  fruits,  and  during  the 
technic  processes  of  fruit  preservation,  such  as  the  making  of  pickles 
and  sauerkraut.  A  number  of  them  will  no  doubt  prove  to  be  budding 
stages  of  other  fungi  for  our  knowledge  of  them  is  decidedly  imperfect. 
The  character  of  the  so-called  pink  yeast,  red  yeast,  and  black  yeast  is 
even  less  well  known.  As  they  are  budding  fungi,  some  have  even 
classed  them  with  the  genus  Saccharomyces.  The  genus  Mycoderma 
was  created  to  include  the  budding  fungi,  which  form  true  films  and 
which  are  formed  rapidly  on  nutrient  liquids,  particularly  on  beer 
and  wine  with  air  between  the  cells,  which  are  usually  short  and  sau- 
sage-shaped. They  are  strongly  aerobic  and  form,  when  exposed  to 
the  air,  a  wrinkled  skin  on  the  surface  of  the  liquid.  Like  the  true  wine 
yeasts,  these  various  species  of  Mycoderma  have  their  natural  habitat 
in  the  soil  and  they  are  carried  to  their  appropriate  nutrient  substances 
by  insects,  rain  or  wind.  They  are  probably  not  true  yeast  plants,  but 
may  represent  growth  conditions  of  other  fungi,  as  related  to  certain 
nutrient  materials.  Curious  chemic  activities  are  possessed  by  species 
of  Mycoderma,  for  example,  the  formation  of  acids  and  their  destruc- 
tion both  at  the  same  time.  Citric  and  succinic  acids  for  example  are 
consumed  by  them. 

1  GuiLLEEMOND,  M.  A.:    Rcchetches  Cytologiques    et   Taxonomiques   sur    les 
Endomycetees.     Revue  Generale  de  Botanique,  21:  401-419,  1909. 


CHAPTER  XVI 
SAC  FUNGI  CONTINUED 

Suborder  C.  Plectasciinese.^This  suborder  includes  fungi  with  a 
well-developed  mycelium  on  which  are  developed  either  on  the  surface 
of  the  substratum  or  within  it,  as  in  the  subterranean  forms,  closed 
perithecia  without  an  opening  at  the  top.  The  wall  of  the  perithecium 
is  sometimes  called  the  peridium.  The  asci  are  developed  on  hyphae 
of  irregular  branching,  and  in  considerable  numbers,  forming  irregular 
layers  of  the  perithecial  interior.  Each  ascus  is  rounded  and  three-  to 
eight-spored.  The  spores  are  one-  to  many-celled.  Condiospores 
occur  in  a  few  of  the  forms,  such  as  Aspergillus,  Meliola  and  Penicillium. 
Many  of  the  fungi  of  this  suborder  are  saprophytic,  but  some  are  de- 
cidedly parasitic,  as  Thielavia  basicola,  which  destroys  the  roots  of  pea 
plants  by  its  parasitic  growth  and  species  of  the  families  Terfeziace^ 
and  Elaphomycetace^,  the  mycelia  of  which  form  mycorrhiza  with 
roots  of  flowering  plants.  Economically,  the  suborder  is  interesting, 
because  it  includes  the  common  blue  and  green  moulds  and  species  of 
Aspergillus  used  in  the  fermentation  industries.  The  fruit  bodies 
of  several  kinds  of  Terfezia  are  used  as  food  by  the  Arabs  of  North 
Africa,  Arabia,  Syria  and  Mesopotamia. 

Family  i.  Gymnoascace^. — The  fungi  of  this  family  are  of  interest, 
because  of  the  structure  of  their  fruit  bodies.  In  the  genus  Gymnoascus, 
the  spheric  asci  arise  on  short  lateral  branches  of  hyphae  which  form  a 
dense  rounded  mass  inclosed  by  loosely  branching  hyphae,  which  form 
a  basket-like  inclosure  of  the  ascus-bearing  portion  Gymnoascus  Reesii 
is  coprophilous.  Some  of  the  shorter  branches  of  this  outer  envelop- 
ment are  sharp-pointed  and  spiny.  Ctenomyces  serratus,  the  single 
representative  of  its  genus,  grows  on  decaying  bird  feathers.  It 
has  branches  with  short  hook-like  extremities.  The  fruit  body  in  this 
fungus  is  similarly  rounded  and  covered  with  hyphae  that  form  an 
open  basket-Hke  peridium. 

Family  2.  Aspergillace^. — This  family  includes  fourteen 
genera,  the  most  important  of  which  are  Aspergillus,  Penicillium  and 

143 


144  MYCOLOGY 

Thlelavia.  The  perithecia  are  never  subterranean.  They  are  usually 
small,  spheric,  usually  closed,  and  their  walls  are  made  up  of  pseudo- 
parenchymatous  hyphge.  They  rarely  open  by  a  pore,  more  usually 
they  break  up  at  maturity  to  allow  the  escape  of  the  ascospores.  The 
inclosed  asci  are  spheric  to  pear-shaped  and  two-  to  eight-spored. 

The  moulds  of  the  genus  Aspergillus  (Figs.  49  and  50)  are  usually 
saprophytic,  and  are  found  upon  decaying  vegetables,  moldy  corn  and 
other  cereals.  After  the  conidiospores  are  formed,  the  color  of  the 
mould  develops  and  various  shades  of  green,  white,  blackish-brown, 
brownish-yellow,  brown  and  reddish  are  found  in  the  different  species 
of  the  genus.  The  recognition  of  this  genus  is  made  easy  by  the  shape 
of  the  conidiophores,  which  are  elongated  unicellular  (unseptate)  and 
terminate  in  a  globular  swelling,  the  top  of  which  is  covered  with  a  large 
number  of  closely  set  stalks,  or  sterigmata,  of  variable  length  and  shape 
on  which  the  conidiospores  develop.  In  the  related  genus  Sterigmato- 
cystis,  the  sterigmata  are  branched  (Fig.  51).  The  conidiospores  are 
spheric,  or  ellipsoidal,  always  unicellular  with  smooth  or  granular 
walls,  and  are  formed  in  long  chains  (concatenation)  from  each  sterigma 
imparting  the  characteristic  color  to  the  whole  growth.  The  perithecia 
are  fragile  spheres  with  thin  walls  which  may  be  yellow  {A.  herbari- 
orum)  dark  red  {A.  pseudo-clavatus) ,  or  even  black  (A.  fumigatus) 
in  color.  The  perithecia  and  asci  are  unknown  in  many  of  the  species, 
so  that  the  classification  of  the  species  cannot  be  based  on  the  characters 
of  that  organ  and  of  the  ascospores.  Only  about  six  to  ten  species  are 
known  to  have  perithecia  out  of  a  possible  total  number  of  120  species 
included  in  the  genus.  This  number  will  probably  be  considerably 
reduced  when  these  moulds  are  better  known.  The  accompanying 
figures  show  some  of  the  specific  differences  of  the  conidiophores  and 
conidiospore  production.  The  .common  green  mould,  Aspergillus 
herbariorum  (=  Aspergillus  glaucus,  Eurotium  Aspergillus  glaucus) 
grows  on  many  substances  such  as  dried  plants  in  the  herbarium, 
(hence  its  specific  name),  on  old  black  bread  (pumpernickel),  on  jellies, 
on  jams,  on  old  leather,  on  herring  pickle  and  other  objects  of  domestic 
use.  At  first  the  mycelium  is  white  and  as  the  young  conidiospores  begin 
to  form  it  turns  to  a  pale  green,  later  becoming  a  dirty  grayish  green, 
while  the  feeding  hyphse  change  color  to  a  pale  yellow  and  finally  a 
brown  color  by  the  deposit  of  pigment  granules.  The  globular  part  of 
the  conidiophore  is  60/x  across  and  crowded  with  simple  sterigmata 


SAC    FUNGI   CONTINUED  I45 

(7M  by  i4m),  bearing  prickly,  spheric  conidiospores  7  to  30^  in  diameter 
which  are  larger  than  any  other  well-known  species.  It  produces 
perithecia  also  with  readiness  and  in  abundance.  The  at  first  pale 
brown-yellow  perithecia,  later  brown,  are  about  100  to  200/i  in  diame- 
ter in  closing  numerous  asci  which  contain  five  to  eight  colorless 
smooth  ellipsoidal  spores,  exhibiting  a  furrow  directed  longitudinally 
and  5  to  8/i  broad  by  7  to  IOf^  long.  The  perithecium  develops  gradu- 
ally from  spirally  coiled  hyphae.     The  hyphae  of  the  screw  are  divided 


Fig.  49. — Aspergillus  oryza  associated  with  yeasts  in  the  making  of  the  Japanese 
beverage  Sake.  Vegetative  hyphae  (a)  and  spore-forming  hyph«  {b.  c,  d)  are  shown. 
Fig.  71,  p.  152.  {Schneider,  Pharmaceutical  Baderiology,  1912,  19.) 

transversely  into  as  many  cells  as  there  are  turns  of  the  screw.  The 
bottom  hyphal  cells  of  the  screw  send  up  two  or  three  branches  of 
irregular  thickness  which  grow  toward  the  apex.  One  of  these  branches 
looked  upon  as  an  antheridium  grows  more  rapidly  than  the  others  and 
its  contents  serve  to  impregnate  the  inclosed  carpogone.  These  outer 
erect  hyphae  then  branch  copiously  to  completely  envelope  the  carpo- 
gone and  the  perithecial  wall  is  thus  formed.  From  the  carpogone  are 
now  formed  the  numerous  ascogenous  hyph;p,  which  branch  plenti- 


146  MYCOLOGY 

fully  and  bear  terminally  asci  of  a  pyriform  shape.  These  contain 
eight  grooved  ascospores.  Aspergillus  herbarioriini,  as  a  domestic 
and  industrial  fungus,  is  selective.  It  does  not  thrive  on  liquid  sac- 
charine media  with  mineral  salts  and  inorganic  nitrogenous  food,  while 
black  bread  and  wort  gelatin  are  suitable  media.  Moderate  tempera- 
tures (8  to  io°C.)  are  best  for  its  growth,  and  it  ceases  growth  entirely 
at  blood  temperatures.  The  temperature  limits  are  7°  to  3o°C.  with 
optimum  at  20  to  25°.  It  grows  on  tobacco,  cigars,  hops,  cotton-seed 
meal,  acid  pickles,  and  smoked  meats.  It  causes  the  blackening  and 
spoiling  of  chestnuts  and  is  found  on  the  kernels  of  various  nuts  even 
before  they  are  removed  from  the  shell  (see  Appendix  VII,  pages  702 
to  721). 

The  rice  mould,  Aspergillus  oryzece  (Fig.  49),  is  of  practical  impor- 
tance as  a  saccharifying  fungus,  and  it  has  been  cultivated  for  centuries 
by  the  Japanese  and  used  by  them  in  the  preparation  of  the  rice  mash 
for  Sake,  as  well  as  in  the  production  of  Miso  and  Soja  sauce.  It  grows 
luxuriantly  and  is  usually  yellow-green  in  color  turning  brown  with  age 
with  large  closely  set  tough  conidiophores  about  2  mm.  tall.  The  tops 
of  its  conidiophores  are  obovate,  or  spheric.  The  sterigmata  are  radially 
arranged  producing  yellowish-green  spheric  conidiospores  (6  to  7/i)  in 
chains.  The  sterigmata  are  larger  than  in  A.  herhariorum  4  to  5^1  by  12 
to  lOjj. .  No  perithecia  have  yet  been  observed.  This  mould  secretes  a 
very  active  diastase  and  it  has  been  used  in  the  making  of  pharmaceutic 
preparations,  such  as  Taka  diastase,  which  is  used  in  the  dose  of  2  to  5 
grains  either  in  tablet,  capsule  or  solution  in  cases  of  indigestion  im- 
mediately after  meals.  It  converts  the  starchy  food  into  dextrin  and 
sugar.  The  discovery  of  this  diastase  in  Aspergillus  was  made  by 
Takamine,  a  Japanese  zymologist,  and  his  product  has  been  used  over 
the  civiHzed  world. 

Aspergillus  Wentii,  which  is  readily  kept  in  culture  on  glucose  or 
beerwort  agar,  is  used  in  the  preparation  of  Tas  Gu  in  Java.  It  appears 
spontaneously  on  boiled  soy  beans  that  have  been  covered  with  leaves 
of  Hibiscus  and  it  causes  a  loosening  and  disintegration  of  the  firm 
tissues  of  the  bean.  The  growth  of  this  species  is  of  a  pale  coffee  color 
with  conspicuous  conidiophores  about  2  to  3  mm.  in  height,  their  thick 
brown  heads  up  to  200/i  in  diameter  are  on  pale  smooth  stalks.  The  end 
of  the  conidiophore  is  globular  75  to  90/x  in  diameter  and  is  covered 
with  slender  simple  sterigmata  (4^  by  15/x)  which  bear  small  globular 
to  elongated  conidiospores,  4  to  5/1  diameter.     The  mycelium  at  first 


SAC   FUNGI   CONTINUED  147 

is  snow-white;  later  it  becomes  reddish  brown.  The  discovery  of 
perithecia  is  yet  to  be  made. 

Aspergillus  flavus  plays  an  important  part  in  the  cocoon  disease  of 
silkworms.  The  stipe  portion  of  its  conidiophore  is  roughened  by 
colorless  granules. 

Aspergillus  luchuensis,  according  to  Inui,  is  used  in  the  preparation 
of  a  beverage  Awamori,  which  resembles  whisky  and  is  used  in  the 
Loochoo  islands. 

Aspergillus  tokelau  is  found  in  Tokelau,  or  Samoan  disease,  attack- 
ing the  natives  of  certain  of  the  Pacific  islands.  An  important  patho- 
genic species,  which  causes  an  epidemic  disease  of  pigeons  and  lives  in 
the  human  ear  and  the  lungs  of  various  birds,  is  Aspergillus  fumigatus, 
which  was  the  cause  of  a  false  tuberculosis  of  a  calf  in  Philadelphia. 
An  autopsy  by  Ravenel  and  the  writer  showed  the  lung  tissue  of  the 
calf  penetrated  by  the  myceUal  hyphae  of  the  fungus,  and  its  conidio- 
phores  bearing  the  conidiospores  in  a  fan-Hke  manner  were  seen  project- 
ing into  the  lung  cavities  almost  completely  filling  them.  It,  therefore, 
grows  well  at  blood  temperature,  and  if  its  conidiospores  are  introduced 
into  the  arterial  circulation  of  animals  they  germinate  and  produce 
serious  illness,  which  may  terminate  fatally.  It  also  acts  injuriously 
in  certain  fermentation  processes  carried  on  at  high  temperatures  as 
certain  lactic  acid  fermentations.  It  attacks  tobacco,  decaying 
potatoes,  bread,  malt  and  beerwort.  It  has  dwarf  conidiophores  o.i 
to  0.3  mm.  long,  with  club-shaped  globules  10  to  20/x  thick,  upright 
sterigmata  6  to  15/1  long  and  with  long  chains  of  conidiospores  (2  to  3^)- 
Nut-brown  globular  perithecia  are  found,  250  to  350M  in  diameter,  in- 
closing oval  thin-skinned  asci  (9  to  i4ju)  with  eight  red  lenticular  tough- 
walled  spores  (4  to  4.5^)-  As  a  parasite  of  the  human  skin  it  was  called 
Lepidophyton.  The  green  mould,  which  usually  grows  on  malt,  is 
Aspergillus  clavatus  causing  a  moulding  of  the  substratum.  The  largest 
species  of  the  group  is  Aspergillus  giganteus,  which  looks  at  first  super- 
ficially hke  a  Mucor,  but  later  owing  to  its  grayish-green  conidiospores 
it  is  readily  separable  from  the  mucor  vegetation.  Its  sterigmata  seem 
to  be  hollow,  communicating  with  a  pore-like  opening  with  the  center 
of  the  conidiophore.  No  perithecia  have  been  found.  Other  species 
are  .4.  nidulans  (Fig.  50),  which  can  be  cultivated  readily,  A.  varians 
and  A.  ostianus,  the  latter  distinguished  by  an  ochraceous  pigment. 
The  black  mould  Aspergillus  niger  more  properly  Sterigmatocystis  niger 


148 


MYCOLOGY 


(Fig.  51)  has  a  copious  literature.     Lafar  cites  forty  workers  of  recent 
date,  who  have  studied  it.     The  physician  finds  it  as  an  occupant  of 


Fig  so — Aspergillus  nidulans.  A,  Mycelium  with  conidiophores;  B,  branched 
conidiophore,  C,  spore  chains  at  end  of  conidiophore ;  D,  small  conidiophores;  E, 
young  fruit  showing  development  of  covering;  jp,  hyphae  with  swollen  ends;  G, 
hypha  from  interior  of  fruit-body;  H,  hyphae  with  young  asci;  J,  developing  perithe- 
cium.      (See  Die  jtaliirlichen  Pflanzenfamilien  I.  i,  p.  302.) 


the  human  ear  in  a  disease  otomycosis.  It  is  associated  with  the  cork 
disease  which  imparts  a  taste  to  bottled  wine.  It  grows  well  in  acid 
substrata,  as  gall-nut  extract,  tannic  acid  and  has  a  decided  capacity 


SAC   FUNGI   CONTINUED 


149 


for  producing  oxalic  acid.  It  has  stiff  slender  conidiophores  several 
millimeters  in  height.  The  terminal  part  can  be  studied  only  after 
the  bleaching  or  removal  of  the  dark  masses  of  conidiophores. 


Fig.  51. — Slerigmatocyslis  niger  {Aspergillus  niger)  showing  conidiophores  and  coni- 
diospore  formation  with  stages  in  germination  of  spores.      {After  Henri  Coupin.) 

The  genus  Thielavia  is  represented  by  a  common  pathogenic  species, 
T.  basicola,  whose  life  history  and  pathogenic  character  will  be  de- 


150  MYCOLOGY 

scribed  later.  It  attacks  the  roots  of  a  large  series  of  plants  including 
the  tobacco,  at  least  105  species  of  plants  being  attacked  according  to 
the  latest  account.^  The  parasitic  mycelium  is  intercellular,  abun- 
dantly septate  and  hyaline.  It  produces  conidiospores,  which  are 
abjointed  acrogenously  from  the  conidiophore,  and  are  not  as  was 
supposed  formerly  endospores  formed  by  free  cell  division  within  an 
endoconidial  cell.  The  first  conidiospore  is  liberated  by  the  differentia- 
tion of  its  walls  into  an  inner  wall  and  a  sheath  and  by  the  rupture  of 
the  latter  at  its  apex.  The  later  conidiospores  grow  out  through  the 
sheath  of  the  first  and  are  freed  by  a  spHtting  of  their  basal  walls.-  This 
same  process  is  probably  that  of  all  "  endoconidia  "  in  fungi. 

Family  3.  Elaphomycetace^. — The  fruit  bodies  of  the  fungi  of 
this  family  are  subterranean  with  a  distinct,  mostly  thick  peridium 
whose  surface  is  marked  by  a  more  or  less  strongly  developed  rind.  The 
asci  borne  within  the  closed  fruit  body  are  irregularly  arranged  and 
united  into  large  groups,  which  are  separated  by  radially  arranged  vein- 
like masses  of  sterile  hyphae.  The  asci  are  spheric,  or  pyriform,  and 
mostly  eight-spored.  The  whole  spore-bearing  interior  of  the  fruit 
body,  when  ripe,  is  transformed  into  a  powdery  mass  with  the  sterile 
hyphae  remaining  as  a  number  of  capillitia-Hke  threads.  There  is  no 
spontaneous  opening  of  the  fruit  body  at  maturity.  The  family  in- 
cludes a  single  genus,  Elaphomyces,  which  comprises  about  twenty-two 
species,  found  mostly  in  northern  Italy,  in  Germany  and  France,  a  few 
in  England,  northern  Europe  and  North  America.  Such  species,  as 
Elaphomyces  papillalus,  E.  atropurpureus  from  the  oak  and  chestnut 
woods  of  northern  Italy,  E.  mutabilis  with  a  silvery-white  mycelium 
growing  in  the  oak,  beech  and  birch  woods  of  northern  Italy,  France 
and  Germany,  E.  citrinus  with  an  orange-yellow  mycelium,  also  from 
northern  Italy,  all  have  delicate  thin  rinds  which  become  wrinkled 
when  dry,  and  belong  to  the  section  Malacodermei.  The  section  Sclero- 
dermei  includes  those  species  with  compact  brittle  rind,  which  is  not 
wrinkled  when  dry.  Here  belong  E.  maculatus  with  strongly  de- 
veloped, green  myceUum,  surface  of  fruit  body  blackish  brown  with 
greenish  markings,  found  in  the  oak  forests  of  northern  Italy,  French 

1  Johnson,  James:  Host  Plants  of  Thielavia  basicola.  Journ.  Agric.  Res., 
vii:  289-300,  Nov.  6,  19 16. 

^  Brierley,  William  B.:  The  Endoconidia  of  Thielavia  basicola;  Zopf,  W., 
Vnnals  of  Botany,  xxix:  483-491,  with  i  plate,  October,  1915. 


SAC   FUNGI   CONTINUED  151 

Jura  and  the  Tyrol.  E.  cerviims,  which  is  found  under  oaks,  beeches 
and  pines  in  Europe  and  North  America,  has  a  fruit  body  the  surface 
of  which  is  brownish  yellow,  or  reddish  brown,  and  is  covered  with 
numerous  pyramid-shaped  projections.  The  inner  layer  of  the  peri- 
dium  of  this  species  is  not  veined  like  E.  variegaius,  another  widely 
distributed  species  throughout  Europe.  The  fruit  bodies  of  the  last 
two  species  are  frequently  parasitized  by  Cordyceps  ophioglossoides 
and  C.  capitatus  (see  ante,  Fig.  21). 

Family  4.  Terfeziace^. — The  fruit  bodies  of  the  fungi  of  this 
family  are  more  or  less  deeply  subterranean,  tuber-like,  infrequently 
galleried  {Hydnobolites).  The  fruit  bodies  differ  from  those  of  the 
preceding  family  in  that  the  interior  spore-bearing  portion  does  not 
break  down  into  a  powdery  mass,  hence  there  is  no  so-called  capillitium, 
and  as  in  that  family  the  fruit  body  does  not  open  spontaneously. 
The  terfas,  or  kames,  of  arid  Mohammedan  countries  belonging  to  the 
genera  Terfezia  and  Tirmania  were  known  to  the  Greeks  and  Romans. 
The  species  of  Terfezia  are  found  under  and  associated  with  the  roots 
of  the  herbaceous  or  shrubby  forms  of  Artemisia,  Cistus  and  Helian- 
themum.  A  North  African  terfa,  Terfezia  conis,  is  found  in  the  moun- 
tain forests  of  pine  and  cedar  and  in  the  sands  of  Sardinia  from  March 
to  April.  The  desert  terfas  include  T.  Boudieri,  T.  Claveryi,  T. 
Hajizi  and  Tirmania  ovalispora.  Duggar,^  an  American  mycologist, 
has  gathered  these  fungi  at  the  base  of  Artemisia  herba-alba  found 
growing  in  the  sandy  soil  of  small  oueds,  or  stream  beds,  in  southwestern 
Algeria.  They  are  located  by  the  breaking  of  the  soil  surface  and  are 
dug  out  -by  the  Arabs  with  a  pointed  stick.  They  form  a  valuable 
food,  as  they  are  rich  in  protem. 

Family  5.  Tuberace^. — General  reference  has  been  made  to  the 
members  of  this  family  in  a  description  of  the  special  ecology  of  the 
EUMYCETES.  The  mycelium  of  the  truffles  is  well  developed  and 
septate,  producing  mostly  subterranean,  tuber-like  fruit  bodies,  which 
have  more  or  less  numerous  chambers  lined  with  the  ascigeral  tissue 
supported  by  sterile  hyphae.  The  asci,  which  are  arranged  irregularly 
in  the  ascigeral  tissue,  are  one  to  eight-spored.  The  ascospores  are 
unicellular,  and  in  the  truffles  {Tuber)  usually  spiny.  The  mycelium 
is  subterranean  and  is  connected  with  the  roots  of  coniferous  and 
broad-leaved  trees  forming  the  so-called  mycorrhiza.     The  simplest 

'  DuGGAR,  B.  M.:  Mushroom  Growing,  191 5:  207-217. 


152 


MYCOLOGY 


Vj 


'm^^^m^- 


Fig.  52. — A,  Tuher  ceslivum  frtiit-body;  B,  Tuber  magnatiim  fruit-body;  C ,  Tuber 
brumale  f.  melanosporum,  section  through  fruit-body;  D,  Tuber  excavalum,  section  of 
fruit-body;  E,  Tuber  ceslivum  f.  mese7!tericuni,  piece  of  fruit-body  near  pcridium  en- 
larged; G,  piece  of  Tuber  excavation  enlarged;.  H,  Tuber  rufum,  fruit-body  magnified 
showing  asci  and  ascospores;  J,  Tiihrr  lirumalc,  ascia  with  spores;  K,  Tuber  magnalum, 
ascus  with  spores.      {See  Die  natiirlidicu  Fjhnizenfamilien  I.  i,  p.  287.) 


SAC    PUNGI    CONTINUED  1 53 

fruit  body  in  the  subfamily  Eutuberine.^  is  found  in  Genea  liispidula 
where  it  forms  a  hollow  sphere  with  definite  opening.  Generally,  it  is 
provided  with  a  system  of  tubes,  passageways  or  galleries,  which  vary 
in  their  arrangement  in  the  different  genera.  These  galleries  are  hollow 
in  some,  in  others  filled  with  hyphje,  constituting  the  vencs  externce. 
The  sterile  supporting  hyphte  between  these  passageways  constitute  the 
vena  inferncB.  In  the  subfamily  Balsaminace^,  the  fruit  body  has  a 
single,  hollow  chamber,  or  numerous  hollow  closed  cavities.  The 
ascigeral  layers  constitute  the  walls  of  these  chambers. 

The  fungi  of  the  genus  Tuber  (Fig.  52)  are  of  the  most  interest 
economically,  as  several  species,  such  as  T.  CBstivum  (Spring),  T. 
brumale,  T.  melanosporum  (^Winter),  T.  uncinatum  (Autumn),  T.rufum 
are  edible,  and  are  known  as  truffles  (Fig.  52).  These  species  occur  in 
deciduous  woods  of  north  Italy,  France  and  Germany  and  elsewhere 
in  Europe.  They  are  gathered  for  food  by  men  (rabassier),  who  make 
a  livelihood  by  selling  the  truffles  for  immediate  use,  or  for  canning 
purposes.  As  the  fruit  bodies  emit  a  characteristic  odor,  they  are 
located  by  the  aid  of  specially  trained  dogs,  and  pigs,  whose  keen  scent 
enables  them  to  find  the  underground  fruit  bodies.  As  they  are  dug 
up,  the  animal  is  rewarded  by  his  master  with  some  other  attractive 
morsel  of  food,  and  the  newly  discovered  truffle  is  placed  in  a  leathern 
pouch  slung  over  the  shoulder  of  the  rabassier.  The  tin  cans  in  which 
the  tfuffles  (Tuber  melanosporum  in  Perigord  mainly)  are  preserved 
for  shipment  to  all  parts  of  the  world  are  usually  labeled  with  a  state- 
ment as  to  the  contents  of  the  can,  and  with  a  hunting  scene,  where  the 
man  and  his  truffle  dog  prominently  figure. 

Near  here  should  be  placed  the  family  Myriangiaceae  repre- 
sented by  the  genus  Myriangium  with  three  species  of  wide  distribu- 
tion.    This  family  has  been  monographed  by  von  Honel.^ 

ivoN  Honel:  Sitzungsber.  Math.  Naturw.  Klasse  k.  Akad.  Wiss.  Wien., 
118,  Abt.  i:  349-376,  1909- 


CHAPTER  XVII 
MILDEWS  AND  RELATED  FUNGI 

Suborder  D.  Perisporiineae. — The  mycelium  of  the  fungi  which 
belong  to  this  suborder  is  filamentous,  superficial,  light-  or  dark- 
colored,  rarely  forming  a  stroma.  The  fruit  bodies  are  superficial, 
spheric  to  egg-shaped  without  a  pore  and  break  up  irregularly.  Peri- 
thecia  are  usually  dark-colored  and  in  many  cases  surrounded  by 
accessory  hyphae,  or  suffulcra.  The  asci  are  spheric,  egg-shaped,  or 
elongated,  and  range  within  the  closed  perithecia  from  one  to  many 
in  number.  Paraphyses  are  usually  absent.  The  following  families 
are  recognized: 

A.  Perithecium  spheric,  poreless  or  breaking  irregularly  at  the  top. 

(a)  Aerial  mycelium  white,  perithecium  with  appendages  or  suffulcra ; 
accessory  spores  belonging  to  the  genus  Oidium. 

I.  Erysiphaceae. 

(b)  Aerial  mycelium  absent,  or  dark-colored,  perithecia  without 
appendages  or  suffulcra,  accessory  spores  not  belonging  to 
Oidium. 

2.  Perisporiace^. 

B.  Perithecium  peltate  flat,  opening  at  top  by  a  round  pore. 

3.    MlCROTHYRIACE^. 

Family  i.  Erysiphace^. — The  fungi  of  this  family  are  popularly 
called  "white"  or  "powdery  mildews."  During  the  summer  their 
conidial  fructifications  (Oidium)  are  found  on  hops,  maples,  peas, 
roses  and  vines  imparting  to  the  surface  of  the  host  a  dusty  appearance, 
due  to  the  white  conidiospores.  Later  in  the  summer,  the  globular 
dark  brown,  or  black,  perithecia  appear  and  these  are  provided  usually 
with  appendages,  or  suffulcra,  which  are  frequently  branched  in  a  way 
characteristic  of  the  different  genera  of  the  family.  The  white 
mycelium  upon  which  the  fruit  bodies  arise  is  truly  parasitic,  for  short 
haustoria  are  formed  which  pierce  the  wall  of  the  epidermal  cells,  and 
swell  out  into  a  bladder-like  form  for  absorptive  purposes.     The  haus- 

i.'54 


MILDEWS    AND    RELATED    FUNGI  1 55 

toria  are  confined  to  the  epidermal  cells  in  all  of  the  genera  of  the 
family  except  Phyllactinia,  which  forms  special  hyphal  branches  which 
enter  the  stomata,  penetrate  the  intercellular  spaces  of  the  leaves  and 
finally  send  haustoria  into  the  cells  of  the  loose  parenchyma.  With 
the  exception  of  these  haustoria,  the  mycelium  of  the  "powdery 
mildews"  is  entirely  superficial.  The  conidial  forms  of  the  different 
fungi  of  the  family  were  classified  formerly  under  the  name  of  Oidium, 
but  with  a  more  detailed  knowledge  of  their  life  history,  this  name  has 
been  relegated  to  the  synonymy.  The  conidiospores,  which  are  formed 
in  great  numbers,  are  carried  by  the  wind,  or  by  snails  in  the  case  of 
Erysiphe  polygoni  on  plants  of  Aquilegia  and  are  capable  of  immediate 
germination  on  reaching  the  epidermis  of  a  suitable  host  plant,  the 
germ-tube  penetrating  the  outer  wall  of  some  epidermal  cell.  True 
sexual  reproduction  has  been  discovered  in  some  of  the  mildews  by 
R.  A.  Harper,  thus  verifying  the  earlier  observations  of  de  Bary. 
Sphcerotheca  Castagnei  serves  to  illustrate  the  process.  The  oogonium 
and  antheridium,  which  are  formed  where  two  neighboring  hyphse 
approach,  each  contains  a  single  nucleus.  The  cell  wall  between  these 
organs  is  dissolved  at  the  time  of  fertilization  and  the  male  and  female 
nuclei  unite  and  a  fresh  wall  is  laid  down  between  the  two  organs. 
Now  the  wall  of  the  future  perithecium  begins  to  form  by  the  develop- 
ment of  a  number  of  upright  hyphal  branches  around  the  oogonium, 
forming  a  pseudo-parenchymatous  tissue,  while  other  branches  later 
absorbed  grow  into  the  interior  of  the  developing  perithecium,  while 
the  outer  wall  cells  become  flattened  and  darker  in  color.  The  fol- 
lowing growth  takes  place  in  Sphcerotheca,  which  develops  only  a 
single  ascus.  The  carpogonium  elongates,  divides  and  a  curved  row 
of  five  or  six  cells  is  formed.  The  penultimate  cell  of  this  row  contains 
two  large  nuclei,  while  the  other  cells  of  the  row  have  one  nucleus  each. 
The  young  ascus  develops  from  this  penultimate  cell  in  which  the  two 
nuclei  fuse  followed  by  a  rapid  increase  in  size  of  the  ascus,  which  presses 
against  the  inner  wall  cells  of  the  perithecium  and  absorbs  them. 
The  nucleus  of  the  ascus  finally  divides  three  times,  producing  the 
nuclei  of  the  eight  ascospores,  which  subsequently  are  formed  by  free 
cell  formation.  From  the  half-grown  perithecium  there  arise  apical, 
equatorial  or  basal  hyphae  which  grow  out  as  the  appendages,  or 
suffulcra,  which  in  Phyllactinia  are  acicular  and  bulbous  at  the  base 
(^ig-  53))  in  Uncinula  hooked  at  the  apex  and  in  PodosphcBra  and  Micro- 


156 


MYCOLOGY 


Fig.   53. —  Mildew  of    chestnut  leaves  due  to  Phyllaclinia  corylei  with  ascus  and 
perithecium  to  left.      (Martic  Forge,  Pa.,  Nov.  2,  igiS-) 


MILDEWS    AND    RELATED    FUNGI 


157 


sphara  (Fig.  54)  dichotomously  branched.  These  appendages  prob- 
ably assist  in  the  distribution  of  the  perithecium,  serving  to  attach 
the  perithecia  to  plants,  if  wind-borne,  or  to  the  bodies  of  insects  by 
which  they  are  carried  to  other  plants.  The  number  of  asci  found  in  a 
perithecium  and  the  number  and  character  of  the  spores  in  the  asci 
vary  generically  (see  Appendix  VIII,  pages  721-726). 

As  the  fungi  of  this  family  are  especially  suitable  for  systematic 
study,  a  key  is  given  not  only  of  the  principal  genera,  but  also  of  the 


anth^ 


Fig.  54. — Lilac  mildew,  Microsphara  alni.  A,  Perithecium  with  appendages; 
B,  perithecia  showing  asci  (a);  C,  ascus  with  ascospores;  D,  conidiophore  (cph), 
bearing  conidiospores  {c.s.);  E,  beginning  of  fertilization;  anth,  antheridium;  car, 
carpogonium;  F,  later  stage  of  fertilization  showing  the  fusion  of  two  nuclei  (/). 
(From  Gager  with  E  and  F  after  R.  A.  Harper.) 


principal  species  of  the  different  genera.  These  keys  (p.  721)  have  been 
taken  from  a  monograph  of  the  Erysiphace^  by  Ernest  S.  Salmon,  pub- 
lished in  1900,  as  vol.  ix  of  the  Memoirs  of  the  Torrey  Botanical  Club,  to 
which  the  mycologic  student  is  referred  for  detailed  descriptions  of  the 
various  species.  The  material  for  the  systematic  study  is  easily  kept 
in  the  dry  condition  and  the  perithecium  can  be  studied  in  situ  on  the 
dried  leaf  or  other  plant  parts,  and  later  treated  with  weak  alcohol 


158  MYCOLOGY 

to  remove  the  air,  washed  and  mounted  permanently  stained,  or 
unstained  in  acetic  acid  with  a  ring  of  asphalt,  or  in  glycerine  jelly 
for  a  study  of  the  asci  and  ascospores.  For  a  study  of  the  distribution 
of  the  haustoria  and  for  a  detailed  examination  of  the  sexual  organs,^ 
small  pieces  (2  by  4  qcmm.)  of  hop  leaves  on  which  myceha  of  the 
mildew  (Sphcerotheca)  are  found  in  various  stages  of  development 
should  be  fixed  in  weaker  Flemming's  solution,  as  described  by  Zim- 
mermann  on  page  178  of  his  "Botanical  Microtechnique,"  and  then 
hardened  in  alcohol  and  carried  through  to  paraffin.  The  sections 
should  be  cut  5  to  7.5^  thick  stained  with  safranin  (one  to  one  and 
one-half  hours),  gentian-violet  (one-half  to  one  hour),  and  orange 
G.  (quickly),  then  treated  with  absolute  alcohol,  cleared  in  oil  of  cloves 
and  mounted  in  balsam. 

The  material  for  systematic  study  should  be  handed  to  members  of 
the  class  in  mycology,  mounted  and  then  studied  as  unknowns  by  the  use 
of  the  generic  and  specific  keys  given  in  Appendix  VIll,  pages  721-726. 

Family  2.  Perisporiace^. — The  aerial  mycelium  of  these  fungi 
is  superficial  black,  filamentous,  or  wanting,  or  rarely  as  a  firm  stroma. 
The  perithecia  are  situated  on  the  aerial  myceUum,  or  on  the  stroma. 
They  are  black,  +  spheric,  rarely  elongated,  poreless,  or  weathering  ir- 
regularly at  the  apex  and  without  appendages.  The  wall  is  mostly 
membranous,  or  brittle.  The  asci  are  clustered  and  mostly  elongated. 
The  shapes  of  the  spores  are  various.  Paraphyses  are  usually  wanting, 
and  are  present  in  only  a  few  cases. 

The  genus  Scorias  has  been  described  incidentally  in  a  foregoing  page 
(72).  It  is  represented  in  America  by  a  single  species,  spongiosa, ^h.\c\\ 
lives  on  beech  twigs  and  leaves  associated  with  some  species  of  wooly 
aphis,  or  on  the  ground  where  the  droppings  of  the  aphis  in  the  form 
of  honey-dew  have  collected.  Its  mycelium  is  greenish-black,  much- 
branched,  rigid,  septate  and  the  hyphae  are  glued  together  by  an 
abundant  mucilaginous  substance  forming  a  loose  spongy  mass,  bearing 
an  abundance  of  pyriform,  coriaceous  perithecia,  which  enclose  narrow, 
thick-walled,  eight-spored  asci.  Elongate  pycnidia  and  perithecia  are 
also  frequently  seen. 

Family  3.  Microthyriace^. — The  mycelium  of  the  fungi  of  this 
family  is  superficial  and  dark  in  color.     The  perithecia  are  superficial 

1  Harper,  R.  A.:  Die  Entwickelung  des  Peritheciums  bei  Sphcerotheca  Castagnei, 
Bericht.  der  Deutsch.  Bot.  Gesellsch.,  xiii,  Heft.  10:  475-481,  1895. 


MILDEWS    AND    RELATED    FUNGI 


159 


shield-shaped,  unappendaged,  black,  membranous  to  carbonous 
formed  of  radiating  chains  of  cells.  The  asci  are  four-  to  eight-spored , 
short  and  associated  with  paraphyses.  Two  fungi  which  attack  the 
cofifee  plant  are  the  most  important  pathogenic  species  of  the  family: 


Fig.  55. — A-D,  Nectria  cinnabarina.  A,  Stroma  of  conidia  and  fruit-bodies  of 
fungus;  B,  stroma  in  section;  C,  ascus;  D,  mycelium  with  conidiospores;  E,  F,  Neclria 
dilissima;  F,  conidia  layer;  G,  H,  Nectria  sinaplica;  G,  ascus;  H,  pycnidia-like  layer. 
J,  Nectria  inaiirita;  K,  Neclria  oropensoides  coremium.  {See  Die  natiirlichen  Pflanz- 
enfamilien  I.  i,  p.  35 7-) 

Scolecopeltis  aeruginea  and  Microthyrium  cofcB.     There   are    twenty- 
one  genera,  and  more  than  300  species  not  well  understood. 

Suborder  E.  Pyrenomycetiinaee.— The  mycelium  is  always  present 
in  these  fungi.     The  perithecia  are  either  located  upon  the  substratum, 


i6o 


MYCOLOGY 


or  in  the  substratum,  and  are  mostly  spheric.  A  wall  (peridium)  is 
present  inclosing  the  clustered  eight-spored  asci  which  arise  from  the 
interior  basal  part  of  the  perithecium.  The  perithecium  opens  by  an 
apical  mouth  or  pore  and  is  either  isolated  or  imbedded  in  a  stroma 
which  takes  manifold  forms.  The  formation  of  conidiophores  and 
conidiospores  varies  in  the  different  families  and  genera.     Sometimes 

a  distinct  conidial  layer  is  formed;  at 
other  times  the  conidiospores  are 
formed  in  pycnidia.  The  suborder 
includes  many  saprophytic  and  para- 
sitic fungi  found  upon  plants  and 
animals. 

Family  i.  Hypocreace^. — The 
perithecium  of  these  fungi  is  spheric 
and  opens  terminally  by  a  definite 
pore.  In  color,  it  may  be  pale, 
sprightly  colored,  or  colorless,  never 
black.  Hypomyces  with  sprightly 
colored  perithecia  arises  from  a  thick 
crust-hke  stroma.  It  lives  parasitic- 
ally  on  a  number  of  different  fleshy 
fungi.  For  example,  Hypomyces 
lactifluorum  transforms  a  species  of 
Lactarius  into  a  cinnabarred  growth 
roughly  resembling  a  toadstool  and 
without  gills,  while  the  original  color 
of  the  host  is  completely  lost  in  the 
higher  color  produced  by  the  parasite. 
Nectria  without  stroma  has  its  peri- 
thecia developed  on  the  surface  of  the 
substratum.  N.  cinnabarina  is  a  par- 
asite on  various  deciduous  trees  (Fig. 
55).  Its  conidial  form  known  as  Tubercularia  vulgaris  produces  flesh- 
colored  eruptions  through  the  bark  of  various  host  plants.  Nectria 
ditissima  grows  on  the  beech.  Polystigma  has  a  crust-like  stroma  on 
the  leaves  of  trees  of  the  genus  Prunus,  while  Epichloe  typhina  con- 
fines its  parasitic  attack  to  grasses  upon  which  it  develops  orange- 
yellow  stroma.     The  genus  Cordyceps  consists  of  species  which  live 


Fig.  56. — Ergot  {Claviccps  pur- 
purea) on  rye  head.  {After  Clinton, 
G.  P.,  Rep.  Conn.  Agric.  Exper.  Stat., 
1903-) 


MILDEWS    AND    RELATED    FUNGI 


[6l 


Fig.  57. — A,  Balansia  claviceps  on  ear  of  Paspalum;  B-L,  Claviceps  purpurea; 
B,  sclerotium;  C,  sclerotium  with  Sphacelia;  D,  cross-section  of  sphacelial  layer;  E, 
sprouting  sclerotium;  F,  head  of  stroma  from  sclerotium;  G,  section  of  same;  H, 
section  of  perithecium;  J,  ascus;  K,  germinating  ascosnore:  ^.  conidiosnores  pro- 
duced on  mycelium.      (See  Die  nalurlichen  Pflanzenfamilien  I.  i,  p.  371.) 


l62  •  MYCOLOGY 

parasitically  on  insects  and  their  larva  and  some  in  subterranean  fungi. 
The  myceHum  kills  the  insect  or  larva  and  mummifies  it.  Out  of  the 
host  grow  conidiophores  (Isaria)  in  early  stages  of  development,  and 
later  stalked  stroma,  in  which  on  enlarged  terminal  portions  the  per- 
ithecia  with  asci  and  ascospores  are  found.  C.  militaris  and  C.  cinerea 
occur  on  insects,  or  insect  larvae.  C.  sinensis  is  found  on  caterpillars 
in  eastern  Asia,  while  C.  ophioglossoides  grows  on  the  fruit  bodies  of 
species  of  Elaphomyces  (see  ante,  page  70)  (Fig.  21).  Claviceps  is  a 
genus  of  fungous  parasites  found  in  the  developing  caryopses  of  various 
grasses.  Its  conidial  stage  was  formerly  known  as  Sphacelia.  Claviceps 
purpurea  and  C.  microcarpa  are  important  species  and  their  life  his- 
tories will  be  described  in  the  third  part  of  this  book.  As  ergot,  the 
sclerotia  of  Claviceps  purpurea  are  used  in  medicine  (Figs.  56  and  57). 
Fifty-seven  genera  and  three  doubtful  ones  are  recognized  and  described 
in  Engler's  Die  natiirlichen  Pflanzenfamilien. 

Family  2.  Dothideace^. — This  family  comprises  twenty-four 
genera  among  the  most  important  of  which  is  Plowrightia  (Fig.  22) 
and  Phyllachora.  The  fruit  bodies  of  these  fungi  is  spheric  with  definite 
mouth  and  without  distinct  peridium,  as  they  are  found  imbedded  in  a 
black  stroma.  Plowrightia  includes  twenty  species  of  fungi,  which 
form  stroma  in  the  interior  of  host  plants,  and  which  break  through  to 
the  surface,  and  form  pimples  in  the  center  of  which  the  opening  to 
the  perithecium  is  found.  The  spores  are  egg-shaped,  two-celled, 
hyaline,  or  bright-greenish.  Plowrightia  ribesia  is  found  on  dried 
twigs  of  species  of  currants  Ribes  in  Europe  and  North  America. 
P.  virgultorum  occurs  on  brick  in  northern  and  middle  Europe,  P. 
Mezerei  grows  on  dead  branches  of  Daphne  in  middle  Europe  and  Italy. 
P.  insculpta  is  found  on  dried  branches  of  Clematis  vitalba  in  Bel- 
gium, France,  Germany  and  Italy  and  P.  morbosa  is  the  cause  of  black- 
knot  of  the  cherry  and  plum  (Prunus)  and  will  be  described  subsequently. 
Phyllachora  is  a  large  genus  of  some  200  species  found  mostly  on  the 
leaves  of  various  plants;  P.  graminis  is  the  commonest  species  of  cos- 
mopolitan distribution  on  grasses  and  sedges.  The  warty  spot  of  clover 
is  Phyllachora  trifolii. 

Family  3.  Sordariace^. — The  perithecia  in  this  family  are 
superficial,  or  deeply  sunken  in  the  substratum  and  often  break  through 
at  maturity.  The  stroma  is  usually  absent,  but  when  it  occurs  the 
perithecia  are  sunken  with  projecting  papilliform  beaks.     The  perithecia 


MILDEWS    AND    RELATED    FUNGI  1 63 

are  thin  and  membranaceous  to  coriaceous,  slightly  transparent  to 
black  and  opaque.  The  asci  are  usually  very  delicate,  surrounded 
by  long  paraphyses,  or  intermingled  with  them.  The  dark-colored 
spores  are  one-  to  many-celled,  surrounded  by  a  hyaline  gelatinous 
envelope,  or  ornamented  with  hyaline  gelatinous  spicula.  The 
SoRDARiACE^  are  entirely  saprophytic  and  grow  on  manure,  hence, 
they  are  coprophilous  fungi.  Special  mechanical  devices  are  shown  by 
the  asci  for  eruptive  spore  discharge  and  the  distance  to  which  the 
spores  are  shot  may  be  between  5  and  9  cm.^ 

Family  4.  Ch^etomiace^. — This  is  a  small  family  of  two  genera, 
ChcBtomium  and  Bommerella,  which  are  found  on  waste  paper,  manure 
and  on  small  living  fungi,  which  resemble  the  fungi  of  the  family 
PerisporiacecB,  if  the  mouth  to  the  perithecium  is  wanting.  Bom- 
merella has  three-cornered  ascospores.  The  perithecia  of  such  forms 
as  ChcBtomium  spirale  and  C.  crispatum  are  provided  apically  with 
masses  of  spirally  wound  ha^'rs. 

Family  5.  Sph^riace^. — This  important  family  includes  parasitic, 
or  saprophytic  fungi  showing  exceptional  diversity  on  dead  parts. 
They  have  rounded  perithecia  with  definite  opening.  The  peridium  is 
evident,  mostly  dark-colored,  membranous  to  leathery  never  fleshy, 
usually  free  from  the  substratum,  or  more  or  less  depressed.  A 
stroma  may  or  may  not  be  present.  Some  authors  include  a  number 
of  families  which  perhaps  may  be  subordinated  here  and  ranked  as 
subfamilies.  Rosellinia  quercina  is  a  disease  of  oak  seedlings.  Myco- 
sphcerella  fr agarics  is  the  cause  of  leaf  spot  of  strawberry;  M.  strati- 
formans  produces  leaf-splitting  blight  of  sugar  cane.  Gulgnardia 
Bidwellii  is  a  most  important  parasite,  being  responsible  for  the  black 
rot  of  the  grape  and  G.  vaccinii  causes  cranberry  scald.  Apple 
scab  and  pear  scab  are  due  to  the  attack  of  Venturia  pomi  and  Venturia 
pyrina.  A  serious  disease  of  sycamore  leaves  in  the  spring  known  as 
anthracnose  is  caused  by  Gnomonia  veneta. 

Family  6.  Valsace^. — The  stroma  of  these  fungi  is  black  and  is 
formed  in  the  substratum  which  is  more  or  less  altered.  The  peri- 
thecia have  a  regular  border  and  take  various  forms  in  the  different 
genera.  The  asci  are  cylindric  and  long-stalked,  alternating  with 
paraphyses.     Pycnidiospores  are  formed  in  pycnidia  and  conidiospores 

1  Griffiths,  David:  The  North  American  Sordariace^.  Memoirs  of  the 
Torrey  Botanical  Club,  xi,  No.  i,  May  7,  1901. 


1 64  MYCOLOGY 

on  definite  conidiospores.  Of  the  ten  genera  of  the  family,  the 
genera  Valsa  and  Diaporihe  are  the  most  important.  Both  genera 
include  about  400  species,  which  are  most  saprophytic  in  wood  and  the 
bark  of  woody  plants.  Valsa  oxystoma  is  the  cause  of  the  disease  and 
death  of  the  branches  of  Alnus  viridis  in  alpine  regions;  Diaporthe 
farinosa  grows  on  the  branches  of  the  linden,  Tilia  americana  in  North 
America  and  D.  eucalypti  on  Eucalyptus  globulus  in  California. 

Family  7.  Melogrammatace.e. — The  stroma  are  mostly  like  those 
of  the  genus  Valsa  and  rarely  like  those  in  Diatrype.  They  are  hemis- 
pheric and  are  formed  beneath  the  bark  and  later  break  through  to  the 
surface,  where  they  are  more  or  less  isolated.  The  perithecia  are 
imbedded  in  the  stroma.  Conidial  fructifications  are  formed  on  the 
surface  of  young  stroma,  or  pycnidiospores  are  produced  in  pycnidia. 
The  most  important  genus  of  this  family  is  Endothia,  which  is  repre- 
sented by  the  Chestnut-blight  fungus  E.  parasitica,  which  lives  in  the 
cambium  and  inner  bark  of  chestnut  trees  causing  a  final  girdling  of 
the  branch  and  the  death  of  the  part  beyond  the  girdled  area.  It  has 
caused  untold  injury  to  the  forest  groves  of  America,  where  the  chest- 
nut tf-ee  abounds,  and  its  morphology  and  its  ravages  will  be  described 
subsequently. 

Family  8.  Xylariace^e. — The  stroma  of  these  fungi  is  developed 
strongly  and  is  frequently  upright  and  branched.  The  perithecia 
are  borne  in  the  branched  club-shaped  portions  of  the  fruit  bodies. 
Early  in  their  growth  the  surface  is  covered  with  conidiospores.  The 
ascospores  are  unicellular  and  blackish-brown.  The  genus  Num- 
mularia,  which  includes  forty  species,  is  represented  typically  by 
N.  Bullardi,  which  causes  black  charcoal-like  eruptions  on  thick 
branches  of  the  beech,  Fagus.  Ustulina,  with  nine  species,  includes 
U.  vulgaris  found  on  old  stems  of  broad-leaved  trees  and  Hypoxylon 
with  about  200  species  is  confined  mostly  to  damp  wood  and  old 
tree  stumps.  Xylaria  digitata,  one  of  the  200  species  of  that  genus, 
grows  on  old  wood,  and  X.  polymorpha  on  old  tree  stumps.  This 
family  completes  the  list  of  pyrenocarpous  fungi. 

Suborder  F.  Discomycetiineae.^ — The  discomycetous  fungi  have  a 
filamentous  mycelium.  Reproduction  is  by  the  union  of  two  hyphal 
branches  either  of  similar  size,  or  differentiated  into  oogonia  and  anthe- 
ridia.  The  fertilized  egg  cell  either  develops  directly  into  an  ascus, 
or  it  develops  ascogenous  hyphas  from  which  the  asci  are  formed. 


MILDEWS   AND   RELATED   FUNGI  1 65 

The  apogamous  formation  of  fruit  also  occurs  in  this  suborder.  The 
asci  are  united  into  definite,  usually  fiat  layers,  which  are  in  open 
fruit  bodies  known  as  apothecia.  Conidiospores  are  also  found  in 
some  of  the  forms  and  the  conidiophores  are  of  diverse  character. 
The  asci  are  usually  eight-spored.  The  fungi  of  this  suborder  are 
either  parasitic,  or  saprophytic  in  habit,  and  a  few  of  the  fleshy  members 
of  the  family  Pezizace^  are  edible. 

Family  i.  Hysteriace^e.^ — The  apothecium  is  elongated  and  the 
opening  is  a  long  wide  cleft  between  the  approaching  walls  of  the 
apothecium,  so  that  the  ascigeral  layer  is  exposed  at  the  time  of  the 
spore  discharge. 

Some  species  of  the  genera  Lophodermium  and  Hypoderma  are 
dangerous  parasites  of  leaves;  for  example,  L.  pinastri  attacks  pine 
leaves;  L.  nervisequum  attacks  the  spruce  tree;  while  Hypoderma 
hrachysporum  is  found  on  the  white  pine,  Pinus  strobus.  Such  genera 
as  Lophium,  Hysterium,  and  Glonium  include  species  which  are  sapro- 
phytic on  bark  and  wood. 

Family  2.  PHACioiACEiE. — The  apothecium  is  rounded,  seldom 
elongated  and  its  walls  are  separated  through  a  star-shaped  opening, 
rarely  a  cleft-like  opening,  so  that  the  ascigeral  layer  is  fully  open  at 
maturity.  The  family  includes  such  parasites  as  Nemacyclus  niveus 
on  coniferous  needles;  Rhytisma  acerinum,  which  produces  black  tar- 
like blotches  on  maple  leaves;  and  R.  salicimim,  which  causes  similar 
black  areas  on  willow  leaves.  Several  species  of  Trochila  are  found 
on  the  leaves  of  different  plants. 

Family  3.  Pyronemace^. — ^The  fruit  body  is  placed  on  fine 
hyphge  or  on  a  felt-like  cushion  of  hyphae.  At  first  it  is  spheric;  later, 
it  is  flatly  expanded.  The  hypothecium  is  occasionally  feebly  de- 
veloped, at  other  times  it  is  strongly  so.  The  peridium  is  poorly  formed, 
or  entirely  absent.  The  most  interesting  genus  is  Pyronema.  P. 
confliiens  has  a  fruit  body  i  mm.  across,  and  of  a  yellow  or  reddish 
color.  It  is  often  found  in  spots  where  fires  have  been  kindled  in  the 
woods.  The  structure  of  the  apothecium  and  the  method  of  its  forma- 
tion following  the  sexual  union  of  an  antheridium  and  oogonium  have 
been  described  by  Harper^  and  the  essential  details  have  been  given 
on  a  former  page  of  this  book  {ante^  pages  123  and  126). 

^  Harper,  R.  A. :  Sexual  Reproduction  in  Pyronema  confluens  and  the  Mor- 
phology of  the  Ascocarp.     Annals  of  Botany,  14:  231-400,  1900 


i66 


MYCOLOGY 


Family  4.  Ascobolace^. — The  apothecia  of  the  fungi  of  this 
family  are  unstalked.  They  are  superficial  and  grow  up  on  manure. 
The  peridium  is  mostly  thin,  or  wanting,  and  the  hypothecium,  which 
is  well  developed,  consists  of  rounded  parenchyma-Uke  cells.  In 
Ascoholus,  the  ascospores  are  discharged  from  the  asci  by  a  squirting 


Fig.  58. — A,  B,  Lachnea  ^culellala.  A,  Habit,  B,  ascus  with  paraphysis;  C,  D, 
Lachnea  hemispharica;  C,  habit;  D,  ascus  with  paraphysis;  E,  Sarcosphara  arenosa 
habit;  F,  G,  Sarcosphara  coronaria;  F,  ascus;  G,  habit;  H,  Sarcosphcera  arenicola 
ascus  with  paraphysis.      {See  Die  nalurlichen  Pjlanzenfamilien  I.  i,  p.  i8i.) 


action,  and  this  is  accomplished  probably  by  the  pressure  of  the  cell 
wall  upon  the  cell  sap.  The  end  of  the  ascus  breaks  open  suddenly,  the 
ascus  collapses,  and  the  eight  spores  are  discharged  simultaneously 
along  with  the  cell  sap.  In  Ascoholus,  which  is  related  to  Pyronema, 
the  ascogonium  is  at  first  multicellular,  but  all  the  cells  empty  their 


MILDEWS    AND    RELATED    FUNGI 


167 


contenls  into  a  single  large  one,  from  which  the  ascogenous  hyphiB 
then  arise. 

Family  5.  Pezizace^. — ^The  apothecia  of  this  family  are  saucer- 
or  cup-shaped,  sessile  or  stalked,  arising  from  a  mycelium  which  is 
found  in  the  substratum.  The  peridium  and  hypothecium  consists 
of  rounded  cells  and  they  are  of  fleshy,  or  leathery  consistency.  The 
asci,  which  are  usually  eight-spored,  are  separated  by  distinct  para- 
physes.  The  spores  are  usually  hyaline.  Lachnea  and  Peziza  are 
the  most  important  genera.  Lachnea  scutellata  (Fig.  58)  has  a 
scarlet  to  vermilion-red  cup,  whose  margin  is  beset  with  a  fringe  of 


Fig.  59. — Saucer-shaped  fruit-bodies  oi  Peziza  re  panda.      (Photo  by  W.  H.  Walmsley). 

large  brown  bristles.  It  grows  on  wet  sticks  and  logs  in  damp,  or  wet 
places,  especially  at  the  water's  edge.  L.  hemisphcerica  has  a  cup  i  to  4 
cm.  wide  with  a  bluish-white  to  gray  disk  and  with  brownish  outside 
bristles  which  fringe  the  margin  of  the  apothecium.  It  grows  on  much- 
decayed  wood.  Peziza  aurantia,  which  is  found  in  the  fall  in  woods, 
and  is  edible,  has  a  bright  orange  cup  i  to  5  cm.  wide,  powdery  outside. 
At  first,  it  is  cup-shaped,  then  saucer-shaped  and  irregular.  It  is 
stemless,  or  nearly  so.  The  spores  are  clear,  elliptic  and  strongly 
netted.  A  woodland  form,  P.  coccinea,  is  scarlet  in  color  and  suggests 
a  wine  glass  in  its  stalked  apothecium.  P.  badia  grows  on  the 
ground  in  grassland  and  woodland,   and  is  also  edible.     It  has    a 


i68 


MYCOLOGY 


dark  brown  to  paler  brown  apothecium,  i  to  4  cm.  across  and  almost 
stemless.  P.  ceruginosa  is  a  stalked,  green  form  whose  mycelium  pene- 
trates the  wood  of  beeches  and  oaks  and  imparts  to  them  a  copper- 
green  color,  which  makes  it  valuable  for  the  manufacture  of  the  famous 
"Tunbridge  ware."  The  attempt  has  been  made  to  extract  the  pig- 
ment, or  to  manufacture  it  synthetically  for  use  as  a  shingle  stain,  but 
without  much  success.  P.  Willkommii  produces  on  larch  trees  a  disease 
known  as  larch  canker.  Other  species  of  Peziza  grow  on  bark  (Fig.  59), 
horse  and  cow  manure,  and  are,  therefore,  typically  coprophilous. 
Family  6.  HelotiacE/E. — The  apothecia  in  these  fungi  are  super- 
ficial from  the  beginning  and  rarely  arise  by  break- 
ing through  the  substratum.  Sometimes  they  de- 
velop from  a  sclerotium  {Sclerotinia).  In  texture, 
they  are  waxy,  leathery  and  thick,  and  stalked,  or 
unstalked,  smooth  or  hairy.  The  asci  are  eight- 
spored.  The  spores  are  round,  elongated,  or  fila- 
mentous, and  one  to  eight-celled,  hyaline.  The 
paraphyses  are  filamentous.  The  fringe  cup, 
Sarcoscypha  floccosa,  has  a  slender,  white,  hairy 
stem,  I  to  3  cm.  long  by  2  to  3  mm.  wide,  and 
bearing  an  apothecium  4  to  10  mm.  wide  with  a 
scarlet  disk,  so  that  the  whole  fruit  body  is  goblet- 
shaped.  The  outside  of  the  cup  is  covered  densely 
with  long  white  hairs  forming  a  fringe  at  the  margin. 
The  spores  are  clear  and  elliptic  20  by  11//.  The 
-Scleroiinia  fringe-cup  fungus  grows  on  decaying  twigs  from 
spring  to  autumn.  Sclerotinia  is  the  most  impor- 
tant genus  economically.  It  includes  about  forty 
species.  The  apothecium  arises  from  a  sclerotium.  Sclerotinia  haccarum 
forms  sclerotia  in  the  fruits  of  Vaccinium  myrtillus;  S.  urnula  (Fig.  71) 
in  those  of  Vaccinium  vitis-idcea.  Sclerotinia  Fuckeliana  forms  sclerotia 
on  the  grape-vine.  Its  conidial  form  was  long  known  as  Botrytis  cinerea. 
Sclerotinia  sclerotioriim  (Fig.  60)  is  parasitic  and  pathogenic  on  a  number 
of  cultivated  plants,  such  as  beets,  and  bears  its  sclerotia  forming  on  the, 
subterranean  parts  of  these  host  plants.  The  black  disease  of  hyacinth 
bulbs  is  connected  with  the  growth  of  Sclerotinia  hulhosum.  Apples, 
pears  and  stone  fruits  are  attacked  by  S.  fructigena.  S.  libertiana. 
causes  lettuce  drop.     S.  trifoUorum  is  responsible  for  the  stem  rot  of 


(After 


MILDEWS    AND   RELATED   FUNGI  1 69 

clover.  Other  fungi  without  sclerotia  are  parasitic  and  destructive. 
Such  are  Dasyscypha  Willkommn,  the  cause  of  larch  canker.  D. 
Warburgiana  is  parasitic  on  cinchona  in  the  tropics.  Such  genera  as 
Coryne,  Helotium,  Lachnum  and  Rutstroemia  are  saprophytic  on  wood. 

Family  7.  Mollisiace^. — ^The  fungi  of  this  family  differ  from 
those  of  the  preceding  largely  in  texture,  the  former  being  tougher  with 
hyphal  cells  modified  in  a  fibrous  manner.  The  spores  are  hyaline. 
Pseudopeziza  is  the  only  important  germs  with  its  apothecium  formed 
beneath  the  epidermis,  which  is  subsequently  ruptured  with  the  pro- 
trusion of  a  shallow  fruit  body.     The  asci  show  eight  unicellular  spores. 

Pseudopeziza  medicaginis  is  the  cause  of  alfalfa  leaf  spot.  Ps. 
ribis  causes  anthracnose  of  currants. 

The  remaining  famiUes  of  the  suborder  are  Family  8,  Celidiace^, 
Family  9,  Patellariace^.,  Family  10,  Cenangiace^. 

Suborder  G.  Helvelliineae. — This  suborder  includes  fungi  with 
a  well-developed  mycelium  which  is  filamentous  and  largely  functional 
for  nutritive  purposes.  From  this  mycelium,  which  penetrates  the 
substratum,  arises  a  fleshy,  waxy  or  gelatinous  fruit  body,  which  usually 
possesses  a  stalk  upon  which  is  raised  an  expanded  portion;  sometimes 
club-like,  in  other  forms  constituting  a  distinct  pileus.  The  expanded 
part,  which  may  be  smooth  and  gelatinous,  wrinkled  or  with  variously 
contorted  folds,  or  of  deep  pits  separated  from  each  other  by  anastomos- 
ing ribs,  is  covered  with  the  ascigeral  layer,  which  consist  of  asci  and 
paraphyses  standing  on  end-like  pahsade  tissue.  The  asci  are  typically 
eight-spored,  rarely,  two-spored,  and  open  at  the  apex  through  the 
removal  of  a  lid,  or  through  a  tube-like  mouth.  The  ascospores  are 
unicellular,  or  multicellular. 

FAivnLY  I.  Geoglossace^. — The  fruit  body  is  fleshy,  waxy,  or 
gristly,  and  is  separable  into  a  stalk,  or  stipe,  and  an  enlarged  fertile 
portion,  the  pileus,  which  is  club-shaped  or  knobbed,  and  its  color  is 
some  shade  of  yellow,  green,  or  black.  The  asci  are  club-shaped, 
opening  by  a  pore  at  the  apex.  This  family  includes  twelve  genera, 
and  it  has  been  carefully  monographed  by  Massee.^ 

Geoglossum  hirsutum  is  an  American  ground  form  with  pileus  flat 

and  black,  2  to  3  cm.  long  and  i  to  2  cm.  wide.     It  is  wrinkled  and 

hairy  (Fig.  61).     The  stem  is  6  to  8  cm.  tall,  black  soUd  and  hairy. 

■'Massee,  George:  A  Monograph  of  the  Geoglosseae.     Annals  of  Botany,  ii; 

225-306  with  2  plates,  1897. 


lyo 


MYCOLOGY 


The  spores  are  brown,  very  long  and  many-celled,  loo  to  120  by  4  to 
7/1.  G.  glutinosum,  another  American  species,  grows  on  the  ground 
among  the  grass.  It  is  black  and  smooth  with  the  ascigerous  portion 
one-third  the  entire  length  of  the  fruit  body  and  in  shape  oblong- 
lanceolate,  slightly  viscid.  The  upper  portion  passes  imperceptibly 
into  the  stalk.  The  spores  are  eight  in  number,  arranged  parallel  to 
each  other  with  obtuse  ends  and  three-septate,  65  to  75  by  5  to  6m, 
and  brown  in  color. 

Leotia  chlorocephala  is  a  fungus  found  in  West  Virginia,  New  Jersey 
and  Pennsylvania.  It  is  cespitose 
in  habit  and  grows  in  mixed  woods 
on  moist  ground,  from  July  until 
late  frosts.  It  is  green  and  has  a 
gelatinous  appearance.  The  pileus 
is  depressed  globose,  more  or  less 
wavy  and  with  an  incurved  border, 
in  color  a  dark  verdigris-green.  It 
is  ecUble.  Another  species,  L.  lubrica, 
is  found  on  the  ground  in  woods  from 
North  CaroUna  and  Minnesota  to 
Massachusetts.  It  is  yellowish,  olive- 
green  with  an  irregular  hemispheric, 
inflated,  wavy  cap. 

Family  2.  HELVELLACEiE. — The 
fruit  body  in  these  edible  .fungi  is 
fleshy  and  divided  into  a  hollow  stalk 
and  ascigerous  expanded  portion. 
The  upper  part  is  cap-Hke  and 
covered  externally  by  the  ascigeral 
layer.  The  asci  are  club-shaped  and  open  by  the  lifting  off  of  a  distinct 
hd.  The  spores  are  ellipsoid,  colorless,  or  bright  yellow  and  smooth. 
Five  genera  are  included  in  the  family:  Morchella,  Gyromitra,  Verpa, 
Cidaris  and  Helvella.  This  family  includes  the  largest  of  the  sac  fungi. 
Some  species  of  Gyromitra  weigh  over  a  pound  and  forms  of  Morchella 
may  grow  a  foot  tall.  The  cap  of  Morchella  is  more  or  less  deeply  ridged , 
crosswise  and  lengthwise  and  has  a  delightful  odor.  The  broad  stem 
Morel,  Morchella  crassipes,  has  a  cap  4  to  10  cm.  tall  and  3  to  6  cm. 
wide  at  the  base,  in  color  tan  to  tan-brown,  with  deep  pits  and  wavy  to 


Fig.  61. — Geoglossum  liirsiUum. 
A,  Appearance  of  fungus;  B,  asci  with 
paraphyses;  C,  spore.  A,  natural 
size;  B,  300/1;  C,  400/1.  {Die  naliir- 
lichen  Pflanzenfamilien  I.  i,  p.  165.) 


MILDEWS    AND    RELATED    FUNGI  171 

irregular  ridges,  the  whole  cap  being  more  or  less  conic.  The  stem  is 
3  to  12  cm.  by  2  to  6  cm.,  white  and  hollow.  The  spores  are  elliptic, 
clear,  smooth,  20  to  22  by  10  to  12/x.  M.  esculenta,  the  common 
Morel,  has  a  cap  3  to  7  cm.  tall  and  2  to  4  cm.  wide,  of  a  yellowish- 
brown  to  brown  color,  covered  with  very  regular  ribs  with  a  blunt 
edge.  The  spores  are  smooth,  elliptic,  clear,  14  to  22^  by  8  to  14/i. 
It  grows  on  the  ground  in  woods  and  forest  openings,  and  is  a  delicious 
morsel. 

Gyromitra  has  a  more  irregular  cap  more  or  less  inflated  and  folded, 
the  edge  united  in  places  with  the  stem.  G.  esculenta  has  a  rounded 
lobed  pileus,  irregular,  gyrose-convolute,  smooth  and  bay-red.  Its 
stem  is  stout,  stuffed,  or  hollow.  The  ascospores  are  elliptic,  yellow- 
ish, 20  to  22M  long.  It  grows  in  wet  ravines,  or  springy  places  in  the 
vicinity  of  pine  groves,  or  pine  trees.  G.  brunnea  is  brown  in  color  and 
is  figured  by  Clements  in  his  "Minnesota  Mushrooms,"  page  143. 

Verpa  digitalijormis  grows  on  ground  in  woods.  It  has  a  brown,  or 
dark  brown,  smooth,  bell-shaped  cap  with  a  long  finger-like  stem, 
beneath,  hence  the  specific  name.  Verpa  bohemica  is  the  "ribbed 
verpa"  and  is  delicious  eating. 

The  cap  in  the  genus  Helvetia  hangs  loosely  over  the  stem  and  it  is 
saddle-shaped  more  or  less  lobed.  The  stem  is  ribbed.  The  ascigeral 
layer  is  confined  to  the  upper  side  of  the  cap.  All  of  the  species  are 
edible.  Helvella  crispa  is  a  common  species  and  has  been  collected  in 
West  Virginia,  Pennsylvania  and  New  Jersey.  It  is  white  or  whitish 
in  color,  while  H.  lacunosa  is  gray  to  almost  black. 

Family  3.  Cyttariace^. — This  family  is  represented  by  the 
single  genus  Cyttaria  with  a  tuber-like  stroma  in  which  the  apothecia 
are  sunken.  The  stroma,  which  arises  on  the  antarctic  beech,  Notho- 
fagus,  in  South  America  and  Tasmania,  is  stalked.  The  asci  are  cyhn- 
dric  and  eight-spored.  The  spores  are  ellipsoidal  and  hyaline.  The 
paraphyses  are  filamentous,  breaking  down  into  mucilage.  The  cylin- 
dric  asci  bear  elliptic  hyaline  spores.  Six  species  have  been  described 
from  Patagonia,  Tasmania  and  Terra  del  Fuego. 

Family  4.  Rhizinace^. — The  fruit  bodies  of  the  fungi  of  this 
small  family  are  stalkless  and  they  are  fleshy  and  waxy  in  consistency. 
Four  genera  are  included. 

Suborder  H.  Laboulbeniineae. — We  owe  our  knowledge  of   these 
eccentric  or  singular  fungi  to  four  botanists:  J.  Peyritsch,  G.  Lindau, 


172  MYCOLOGY 

Roland  Thaxter  and  J.  Faull.  They  are  parasitic  on  insects,  mostly 
beetles,  which  live  in  moist  situations  and  are  long-lived  and  hiber- 
nating. They  are  often  highly  specialized,  as  to  the  parts  of  the 
insect  on  which  they  grow,  occurring  only  on  certain  joints  of  the  legs 
and  on  certain  legs  of  the  host.  The  vegetative  mycelium  is  very  much 
reduced,  consisting  of  one  to  a  few  cells,  which  are  attached  to  the  body 
of  the  insect  and  their  usually  minute  size  renders  them  difficult  of 
study.  The  host  is  not  destroyed  nor  even  inconvenienced  by  these 
fungi  which  appear  as  minute,  usually  dark-colored,  yellowish  bristles 
or  bushy  hairs  projecting  from  the  chitinous  integument  of  the  insect. 
Stigmatomyces  BcbH  lives  parasitically  on  house  flies.  The  bicellu- 
lar  spore  with  its  mucilaginous  coat  becomes  attached  at  its  lower  end. 
The  upper  cell  develops  an  appendage  which  bears  a  number  of  unicel- 
lular flask-shaped  antheridia  from  which  the  naked  spermatia  are  shed. 
The  lower  cell  divides  into  four  cells  which  represent  the  female  repro- 
ductive organ,  where  the  carpogonium,  or  egg  cell  develops  a  trichogyne 
to  which  the  spermatia  become  attached.  The  three  fundamental  parts 
of  which  these  plants  are  composed  are  a  main  body,  the  receptacle; 
one  or  more  spore-producing  portions,  the  perithecia;  and  lastly,  one  or 
more  appendages  which,  in  the  majority  of  cases,  are  associated  with 
the  formation  of  the  male  sexual  organs.  The  receptacle  is  that  por- 
tion of  the  fungus  on  which  the  appendages  together  with  the  perithe- 
cia, or  their  stalk  cells,  are  inserted.  The  sterile  appendages,  which 
form  dense  tufts  and  sometimes  are  more  conspicuous  than  the  main 
plant  itself,  serve  to  protect  the  delicate  trichogyne  which  is  subse- 
quently developed.  Sometimes,  the  primary  appendage  develops  a 
spine-Uke  process.  The  male  organs  and  male  elements  in  the  Laboul- 
BENiACE^  may  be  designated  as  antheridia  and  antherozoids,  the  former 
consisting  of  a  single  antheridial  cell  or  a  group  of  such  cells,  the  latter 
of  a  single  naked,  or  thin- walled  cell,  so  that  the  antherozoids  are  pro- 
duced either  endogenously  or  exogenously.  Among  the  antheridia 
which  produce  endogenous  antherozoids  we  may  distinguish  the 
simple  and  the  compound.  A  simple  antheridium  discharges  its 
antherozoids  through  its  special  pore  or  opening,  the  compound  an- 
theridium consists  of  several  antheridial  cells  each  of  which  dis- 
charges its  contents  into  a  common  cavity  from  which  they  es- 
cape. The  female  organs  are  formed  from  a  segment  of  the  lower 
cell  of   the  receptacle  rarely  from   the   terminal  cell.     The  perithe- 


MILDEWS   AND   RELATED   FUNGI  1 73 

cium,  as  in  many  other  Ascomycetales,  originates  from  a  cell  of  the 
receptacle  situated  below  the  female  organ.  The  procarp  consists  of 
three  distinct  parts:  the  trichogyne,  the  trichophoric  cell  and  the  part 
lowest  the  carpogenic  cell,  which  is  fertilized  and  undergoes  further 
development.  FaulP  has  shown  in  two  species  of  Laboulhenia  that  after 
the  procarp  is  mature  the  carpogonium  and  trichophoric  cell  become 
continuous.  Meanwhile,  the  nucleus  of  the  carpogonium  is  succeeded 
by  two  which  are  apparently  daughters  of  the  carpogonial  nucleus,  and 
almost  simultaneously  the  trichophoric  nucleus  undergoes  division. 
Later,  a  uninucleate  trichophoric  cell  and  a  uninucleate  inferior  sup- 
porting cell  are  septated  off  from  the  now  four-nucleated  fusion  cell. 
After  further  nuclear  divisions  a  binucleate  superior  supporting  cell  and 
sometimes  a  binucleate  inferior  supporting  cell  are  cut  off.  The  binu- 
cleate ascogonium  now  begins  to  bud  off  asci,  or  divides  into  two  asco- 
genic  cells,  each  of  which  contains  a  pair  of  nuclei.  Up  to  this  stage  no 
nuclear  fusions  have  been  observed.  The  nuclei  of  an  ascogenic  cell 
divide  conjointly,  a  daughter  of  each  passing  into  a  young  ascus.  This 
process  is  repeated  at  the  birth  of  every  ascus.  The  pair  entering  the 
ascus  soon  fuse.  The  fusion  nucleus  divides  by  a  reduction  mitosis 
after  a  period  of  growth  and  the  number  of  chromosomes  is  the  same 
as  in  other  mitoses.  There  are  two  other  mitoses  prior  to  spore  forma- 
tion, and  both  are  homotypic.  The  spores  are  delimited  by  the  method 
characteristic  of  the  ordinary  sac  fungi.  Each  ascus  in  Stigmatomyces 
BcBfi  produces  four  spindle-shaped  bicellular  spores.  In  other  genera 
eight  two-celled  spores  are  formed.  It  is  to  be  noted  in  closing  that  the 
sexual  organs  of  these  curious  fungi  are  similar  to  those  of  the  red 
seaweeds,  Floride^.  Thaxter^  has  done  more  than  any  other  botanist 
to  make  this  order  known  systematically. 

Phylogeny  oj  Ascomycetales. — Atkinson  in  a  philosophic  discussion  of 
the  phylogeny  of  the  Ascomycetales  suggests  six  series  or  lines  of 
development  and  his  suggestions  are  incorporated  in  the  accompanying 
chart. 

I.  Apocarp  line  from  Dipodascus-\\ke  forms  and  by  reduction. 

1  Faull,  J.  H. :  The  Cytology  of  the  Laboulbeniales.  Annals  of  Botany, 
XXV :  649-654,  July,  191 1.  The  Cytology  of  Laboulhenia  chsetophora  and  L. 
gyrinidarum.     Annals  of  Botany,  xxvi:  355-358,  with  4  plates,  April,  191 2. 

-  Thaxter,  Roland:  Contributions  toward  a  Monograph  of  the  Laboulbeniaceae 
part  I,  1896;  part  II,  1908,  Mem.  Amer.  Acad,  of  Arts  and  Sci. 


174  MYCOLOCxY 

2.  Plectocarp  line  from  Dipodascus-like  forms,  perhaps  similar  to 
Monascus. 

3.  Perispore  line  arising  from  Monascus-Ukc  prototype,  before  split- 
ting of  archicarp,  or  from  Aspergillace^. 

4.  Pyrenocarp  line  arising  near  Monascus-like  prototype,  Laboul- 
BENiALES  side  near  base,  and  some  of  the  Mycothyriales  as  reduced 
from  Sph^riales. 

Those  who  adhere  to  the  behef  that  the  AscomycAtales  have 
descended  from  the  red  algae  interpret  their  belief  in  three  ways:  first, 
sac  fungi  with  highly  developed  trichogyne  of  the  Collema  type  with  cer- 
tain red  algae  of  existing  forms;  second,  sac  fungi  with  highly  developed 
trichogyne  of  the  Polystigma  type  with  hypothetic  algae  with  trichogyne 
representing  the  common  original  stock  of  both  groups;  and  third,  sac 
fungi  with  simple  generalized  copulating  gametes  of  the  Gymnoascus 
type  with  hypothetic  algae  having  a  simple  procarp  representing  the 
stock  from  which  both  groups  started.  It  will  be  noted  that  Atkinson 
believes  that  the  fungi  of  the  Ascomycetales  have  been  derived  from 
the  simple  Phycomycetes,  and  that  thePROXOASCOMYCETES  are  der'ved 
by  descent  and  degeneration  from  such  a  primitive  form  as  Dipodascus, 
Endomyces  Magnusii  being  the  nearest  known  form  to  the  generalized 
condition  seen  in  Dipodascus.  The  Euascomycetes  are  derived  from 
fungi  similar  to  Monascus  and  Gymnoascus  with  generalized  archicarp. 
Six  distinct  lines  as  previously  noted  arise  from  these  primitive  forms. 
Atkinson  gives  a  chart  which  is  purely  provisional,  and  which  suggests 
the  probable  relationship  of  the  principal  groups  to  each  other  and  to  a 
probable  common  ancestor. 

GENERAL  BIBLIOGRAPHY  OF  THE  ASCOMYCETALES 

Atkinson,   Geo.  F.  :  Phylogeny  and  Relationships  in  the  Ascomycetes.     Annals 

of   the  Missouri    Botanical  Garden,  ii:    315-376,  February-April,  1915. 
Barker,  B.  T.  P. :  The  Morphology  and  Development  of  the  Ascocarp  in  Monascus, 

with  2  plates.     Annals  of  Botany,  xvii:  167,  1903. 
Blackman,  H.  H.  and  Welsford,  E.  J. :  The  Development  of  the  Perithecium  of 

Polystigma  rubrum.     Annals  of  Botany,  xxvi:  761,  191 2,  with  2  plates. 
Brown,  Horace  T.:  Some  Studies  in  Yeast.     Annals  of  Botany,  xxviii:  197,  1914- 
Carruthers;  D.:  Contributions  to  the  Cytology  of  Helvella  crispa,  with  2  plates. 

Annals  of  Botany,  xxv:  243,  191 1. 
Clements,  F.   E.:  Minnesota  Plant  Studies:  iv,   Minnesota  Mushrooms,    1910: 

138-151- 


MILDEWS    AND    RELATED    FUNGI  1 75 

Conn,  H.  W.  :  Bacteria,  Yeasts  and  Moulds  in  the  Home,  1903,  with  293  pages. 
DuGGAR,  B.  M.:  Mushroom  Growing,  1915,  pages  188-224,  dealing  with  European 

Truffles,  Terfas  and  Morels. 
Ellis,  J.  B.  and  Everhart,  J}.  M.:  The  North  American  Pyrcnomycetes,  1892, 

pages  793,  with  41  plates. 
Engler,   a.:  Die   Natiirlichen   Pllanzenfamilien,   I.   Teil,    i    Abt. :    142-505    with 

separate  parts  by  Ed.  Fischer,  G.  Lindau  and  J.  Schroeter. 
Faull,   J.   H.:  The   Cytology   of   the  Laboulbeniales.     Annals  of   Botany,    xxv: 

649-654,  July,  191 1. 
Faull,  J.  H.:  The  Cytology  of  Laboulbenia  chajtophora  and    L.   Gyrinidarum. 

Annals  of  Botany,  xxvi:  325-355,  with  4  plates,  April,  191 2. 
Eraser,  H.  C.  I.  and  Ullsford,  E.  J.:  Further  Contributions  to  the  Cytology  of 

the  Ascomycetes,  with  2  plates.     Annals  of  Botany,  xxii:  331,  1908. 
Eraser,  H.  C.  I.  and  Brooks,  W.  E.  St.  T.:  Further  Studies  on  the  Cytology  of 

the  Ascus.     Annals  of  Botany,  xxiii:  537,  1909. 
Eraser,  H.  C.  I.  and  Gwynne-Vaughan  Mrs.  D.  T.:  The  Development  of  the 

Ascocarp  in  Lachnea  Cretea,  with  2  plates.     Annals  of  Botany,  xxvii:  553,  1913. 
Grant,  James:  The  Chemistry  of  Bread  Making,  191 2:  125-152. 
Griffiths,  David:  The  North  American  Sordariacese.     Memoirs  Torrey  Botanical 

Club,  xi,  1901. 
Jorgensen,    Alfred:  Microorganisms    and    Fermentation,     transl.     3d    Edition 

by  Alex.  K.  Miller  and  A.  E.  Lennholm,  1900,  with  318  pages. 
Kohl,  Dr.  F.  G.:  Die  Hefepilze  ihre  Organisation,  Physiologic,  Biologic  and  Sys- 

tematik  ihre  Bedeutung  als  Giirungsorganismen,  1908. 
Klocker,   Alb.:  Fermentation  Organisms:  A  Laboratory  Handbook,   transl.   by 

G.  E.  Allan  and  J.  H.  Millar,  1903,  with  391  pages. 
Lafar,  Dr.  Franz:  Technical  Mycology,  transl.  by  Charles  T.  C.Salter.      II,  Part 

I:  99-189:  Part  II:  191-481. 
Massee,  George:  A  Revision  of  the  Genus  Cordyceps.     Annals  of  Botany,  ix:  i, 

with  2  plates. 
Massee,   George:    A  Monograph  of   the    Geoglosseae.     Annals  of  Botany,   11: 

225-301,  1897. 
Massee,  George:  The  Structure  and  Affinities  of  the  British  Tuberacese,  with  i 

plate.     Annals  of  Botany,  xxiii:  243,  1909. 
Massee,  George:  Text-book  of  Fungi,  1906:  261-313. 
Salmon,  E.  S.  :  On  Endophytic  Adaptation  Shown  by  Erysiphe  graminis.     Annals 

of  Botany,  xix:  444. 
Salmon,  E.  S.  :  On  Oidiopsis  taurica,  an  Endophytic  Member  of  the  Erysiphaceae. 

Annals  of  Botany,  xx:  187,  1906. 
Salmon,  Ernest  S.  :  A  Monograph  of  the  Erysiphaceae.     Memoirs  Torrey  Botan- 
ical Club,  ix,  1900,  pages  287,  with  9  plates. 
Stevtens,   F.   L.:  The   Fungi   Which  Cause  Plant  Disease,   1913:  113-297,   with 

bibliography. 
Thaxter,   Roland:  Contributions  toward  a  Monograph  of  the   Laboulbeniaceie, 

part  I,  Mem.  Amer.  Acad.  Arts  &  Sci.,  1896;  part  II,  do.,  1908. 


1^5  MYCOLOGY 

Thon,  Charles:  Cultural    Studies  of    Species  of    Penicillium.     Bull.   ii8,  U.  S. 

Bureau  Animal  Industry,  1910. 
Wager,  Harold:  The  Nucleus  of  the  Yeast  Plant.     Annals  of  Botany,  xii:  499- 

540,  with  2  plates,  1898. 
Wf.ttstein,  Dr.  Richard  R.  von:  Handbuch   der  Systematischen   Botanik   (2d 

Edition),  iqii:  168-192. 


CHAriER  XVIII 

BASIDIA-BEARING  FUNGI  (SMUTS) 

ORDER  BASIDIOMYCETALES 

The  fungi  of  this  order  have  mostly  a  strongly  developed  mycelium, 
multicellular  and  at  times  with  apical  growth.  Sexual  reproduction  is 
entirely  absent,  yet  in  the  rusts,  we  find  certain  nuclear  fusions  which 
are  looked  upon  by  some  mycologists  as  of  a  sexual  nature.  The 
characteristic  method  of  reproduction  is  non-sexual  by  means  of  conidia, 
which  in  the  most  primitive  forms  are  of  indefinite  number, 
while  in  the  most  highly  differentiated  forms  the  conidiospores  are 
definite  in  number  two  to  eight,  and  are  borne  on  special  conidio- 
phores  known  as  basidia  (basidium-ia).  In  many  forms,  the  basidia 
are  arranged  in  definite  parts  of  fleshy  fruit  bodies  and  in  special  layers 
known  as  hymenia  (hymenium-ia).  Besides  the  conidiospores  other 
kinds  of  spores,  known  as  chlamydospores,  are  formed.  Zoospores  are 
entirely  absent.  The  fungi  of  the  order  are  either  saprophytes,  or 
parasites,  and  occasionally,  they  are  facultative  saprophytes,  or  faculta- 
tive parasites.    None  of  them  live  in  the  water  (nicht  wasserbewohnend) . 

The  Basidiomycetales  do  not  follow  the  Ascomycetales  in  the  direct 
line  of  evolution  of  the  fungi.  They  may  be  considered  to  parallel  the 
sac  fungi.  The  group  is  supposed,  in  this  regard,  to  represent  the  results 
of  extreme  simplification;  the  sexual  organs,  if  ever  present,  have  in 
the  phylogenetic  history  of  these  fungi  long  since  disappeared  and 
simple  nuclear  fusions  function  in  all  probability  in  lieu  of  the  sexual 
act. 

Key  to  Suborders  of  the  Basidiomycetales  (After  Stevens) 

Chlamydospores  at  maturity  free  in  a  sorus,  produced  intercalary, 
from  the  mycelium;  basidiospores  borne  on  a  promycelium  and  resem- 
bling conidiospores.     i.  Hemibasidii. 

Chlamydospores  absent,  or  when  present,  borne  on  definite  stalks. 

Basidia  septate,  arising  from  a  resting  spore,  or  borne  directly  on  a 
hymenium.     2.  Protobasidii. 

Basidia  non-septate,  borne  on  a  hymenium.     3.  Eubasidii. 
177 


178  MYCOLOGY 

Suborder  Hemibasidii. — The  conidiophore,  or  more  correctly  the 
basidium,  arises  from  the  chlamydospore  and  bears  an  indetinite 
and  usually  large  number  of  basidiospores.  All  cells  of  the  mycelium 
and  the  spores,  as  far  as  known,  are  unicellular.  The  position  of  this 
suborder  in  the  family  tree  of  the  fungi  is  uncertain.  The  majority 
of  the  funguses  are  strictly  parasitic  on  the  higher  plants,  and  their 
mycelia  live  in  the  tissues  of  the  same,  mostly  as  intercellular  parasites, 
certain  hyphae  known  as  haustoria  penetrating  the  interior  of  the  host 
cells.  Infection  of  the  host  takes  place,  as  a  rule,  very  early  and  in 
some  cases  at  the  time  of  seed  formation,  so  that  the  parasitic  mycelium 
keeps  pace  with  the  growth  of  the  host  plants  and  at  definite  times  and 
places,  such  as  anthers,  ovaries  and  the  like,  which  are  mostly  de- 
formed, the  spore-bearing  portion  of  the  fungous  parasite  appears. 
The  spores,  which  are  formed  in  such  places,  are  known  as  chlamydo- 
spores,  and  the  mass  of  spores  and  diseased  host  parts  are  mostly 
black  and  soot-like.  The  chlamydospores  give  rise  to  a  promycelium, 
which  cuts  off  basidiospores.  The  basidiospores  give  rise  either  to 
conidiospores,  or  they  infect  some  host  plant,  if  deposited  upon  it  at 
the  susceptible  time.  Brefeld  first  suggested  the  name  Hemibasidii  for 
the  UsTiLAGiNACE^  and  Tilletiace^  which  he  considered  as  repre- 
senting the  link  connecting  the  lower  fungi  and  the  true  BASIDIO- 
MYCETALES.     Two  famiUes   are   recognized  by  mycologists,  viz., 

USTILAGINACE^  and  TlLLETIACE^. 

Family  i.  Ustilaginace^e. — ^The  fungi  of  this  family  are  all  para- 
sitic. They  can  be  recognized  readily  by  the  outbreaks  of  dusty 
material  that  they  produce  on  certain  parts  of  their  hosts,  when  they 
reach  their  reproductive  stage.  An  important  genus,  Ustilago,  the 
type  genus  of  the  family,  derives  its  name  from  ustio,  a  burning.  The 
smut  of  wheat  is  called  locally  in  England  "bunt  ear,"  "black  ball," 
"  dust  brand"  and  "  chimney  sweeper."  All  of  these  names  are  indica- 
tive of  the  sooty-black  character  of  the  spores.  There  are  two  chief 
phases  in  the  development  of  a  smut  fungus,  the  mycehal  phase  and 
the  spore  phase.  The  hyphae  of  the  mycelium  mostly  push  between 
the  cells  through  the  intercellular  spaces  and  form  short  special  branches, 
or  haustoria,  which  enter  the  host  cells  and  absorb  from  them  nutritive 
material.  The  mycelium  may  be  locahzed,  or  it  may  be  spread  gen- 
erally throughout  the  host.  Where  the  mycelium  gains  entrance  to 
the  host  through  the  germinating  seeds,  it  remains  in  the  vegetative 


BASIDIA-BEARING    FUNGI    (SMUTS)  1 79 

condition  and  without  external  manifestation  of  infection  until  in  its 
fruiting  stage,  when  it  breaks  through  the  tissues  of  the  host,  appear- 
ing at  the  surface.  In  perennial  plants,  the  mycelium  may  live  in  the 
perennial  parts,  each  year  extending  into  the  new  growth.  Eventually, 
the  mycelium  becomes  conspicuous  in  certain  organs  of  the  plant.  It 
may  develop  abnormal  growths,  or  cause  swellings  in  the  stem  leaves, 
flowers  (anthers,  ovaries),  or  fruits  of  the  host.  Here  the  hyphae  break 
up  into  chains  of  spores,  which  develop  thicker  walls  than  the  hyphal 
cells  from  which  they  arose  and  are  known  as  chlamydospores  (xXayuus, 
xXctfxvdos  =  a  cloak  +  (rwopa  =  a  seed).  The  hyphal  cells  between  the 
spores  undergo  almost  complete  gelatinization,  which  gelatinized  cells 
are  used  probably  to  nourish  the  developing  spores,  as  at  maturity  the 
spores  lie  loosely  surrounded  in  part  by  the  diseased  cells  of  the  host 
ready  to  be  discharged  as  the  adjoining  hyphal  and  host  cells  dry  up 
and  completely  disappear.  The  chlamydospores,  which  make  up  the 
smutty,  or  sooty  masses,  are  usually  thick-walled  and,  being  small, 
4  to  35^t,  they  are  easily  disseminated.  They  are  usually  spherical,  or 
spheroidal,  but  may  be  ovoid,  eUipsoidal  or  even  oblong.  They  are 
simple,  i.e.,  consisting  of  single  cells,  but  they  may  be  united  into  spore 
balls,  which  may  have  an  external  coating  of  sterile  cells.  The  galls 
of  the  chlamydospores  may  be  smooth,  or  echinulate,  or  reticulate  with 
a  network  of  ridges,  or  wings.  Their  color  may  be  yellowish,  reddish 
or  olive-brown,  violet,  or  purplish,  and  the  dark-colored  spores  in  mass 
may  appear  to  be  black  or  dark  amber-brown.  Sori  are  masses  of  the 
spores  that  break  out  singly,  or  in  clusters,  on  the  various  organs  of 
the  hosts.  These  clusters  are  protected  by  their  coverings  of  the  tissue 
of  the  host.  The  sori  may  be  dusty  and  easily  broken  up,  while  in 
other  species,  they  may  be  hard  and  the  spore  mass  is  gradually 
disintegrated. 

The  wind  is  undoubtedly  one  of  the  principal  agents  in  the  dissemi- 
nation of  the  smut  spores,  but  it  was  found  that  no  smut  spores  could 
be  demonstrated  in  spore  traps  set  up  at  the  University  of  Manitoba 
by  BuUer  farther  distant  from  the  infected  fields  than  250  yards.  Man 
distributes  the  spores  through  unclean  agricultural  methods,  such  as 
using  old  grain  bags  over  and  over  again,  and  in  sowing  seed  to  which 
the  smut  spores  are  attached.  The  threshing  machine  is  an  active 
agent  in  the  spread  of  smut  spores,  and  the  farmer  should  see  that  his 
machine  is  carefully  cleaned  from  one  operation  to  another. 


i8o 


MYCOLOGY 


Fig.  62. — Germination  of  smut  spores,  a,  Chlamydospores;  b,  basidium;  5, 
basidiospores;  d,  infection  threads;  e^  detached  pieces  of  mycelia;  /,  knee-joints,  i. 
Germination  of  Ustilago  avenae  in  1/  50  per  cent,  acetic  acid  24  to  48  hours  after  being 
placed  in  liquid.  2.  Same  as  in  i  but  in  distilled  water.  3.  Germination  of  Ustil- 
ago levis  in  Cohn's  modified  solution  at  end  of  24  hours.  4.  Same  as  3  but  at  end  of 
2  or  3  days.  5.  Germination  of  Ustilago  Iritici  in  Cohn's  modified  solution.  6.  Ger- 
mination of  Ustilago  striafortnis  from  red  top  in  1/  .50  per  cent,  acetic  acid  at  end  of 
2  days.  7.  S'ame  as  6  except  in  Cohn's  modified  solution.  {After  Bull.  57,  Univ. 
III.  Agric.  Exper.  Stat.,  March,  igoo.) 


BASIDIA-BEARING    FUNGI    (SMUTS)  l8l 

Experiments  to  determine  the  vitality  of  smut  spores  have  shown 
that  those  of  the  stinking  smut  of  wheat,  covered  smut  of  barley  and 
oat  smut  are  long-Hved  under  favorable  conditions  for  seven,  or  eight 
years,  and  in  a  dry  condition  are  resistant  to  frost.  Where  vegetative 
reproduction  occurs,  as  in  the  loose  smuts,  the  spores  lose  their  vitality 
after  five  to  six  months.  It  has  also  been  determined  that  stinking 
smut  spores  passing  through  the  bodies  of  animals  lose  their  power  of 
germination  in  a  great  majority  of  cases.  Only  those  passing  through 
pigs  retain  their  vitaHty  a  longer  time.  The  presence  of  occasional 
viable  spores  in  the  manurial  offal  of  animals  suggests  a  danger  of 
the  spreading  of  smut  diseases  through  manure  applied  to  fields  as 
fertihzers. 

Germination  (Fig.  62). — The  spores,  when  placed  in  a  drop  of 
water,  send  out  a  single  hyaline  thread  several  times  the  length  of 
the  spore,  and  this  thread,  or  promycelium,  becomes  divided  into  four 
cells  by  cross-partitions,  or  septas.  Usually  the  apex  of  these  four  cells 
produce  one  or  more  elongated  thin-walled  spores,  the  basidiospores, 
or  sporidea.  These  basidiospores  are  pinched  ofif  at  the  base,  and 
others  are  formed  to  take  their  place.  When  the  basidiospores  reach 
the  proper  host,  whether  in  the  seed,  seedling,  partly  grown  or  mature 
condition,  it  forms  on  germination  an  infection  hypha,  which  bores 
through  the  surface  and  enters  the  interior  of  the  host.  Once  inside  a 
mycelium  is  formed. 

Modes  of  Infection. — (i)  Certain  smut  spores,  as  those  of  the 
stinking  smut  of  wheat,  covered  smut  of  barley,  naked  and  loose  smuts 
of  oats  and  others,  adhere  to  the  outside  of  the  grains  and  are  sown 
along  with  the  grain.  In  the  soil  germination  takes  place  and  the  spore 
produces  a  short  stout  mycelium,  which  develops  secondary,  or  even 
tertiary  spores,  which  by  means  of  infection  threads  attack  the  young 
grain  seedlings  as  they  grow  upward  through  the  soil.  This  mode  of 
infection  is  called  seedling  infection.  (2)  In  the  so-called  loose  smuts 
of  wheat  and  barley,  the  chlamydospores,  which  are  mature  at  the  time 
of  flowering  of  these  commercial  grasses,  fall  upon  the  female  organs 
of  the  wheat,  or  barley,  and  germinating  the  infection  hypha  pushes 
its  way  into  the  developing  grain  where  it  remains  dormant  as  a  deli- 
cate mycelium.  The  normal  development  of  the  grain  is  not  inhibited, 
so  that  when  it  is  planted  as  seed,  the  mycelium  begins  to  grow  with 
the  seedling  and  keeps  pace  with  the  future  growth  of  its  host  until 


I 82  MYCOLOGY 

the  maturity  of  the  spores  at  the  time  the  wheat,  or  barley,  come  into 
bloom.  This  mode  of  infection  is  known  as  flower  infection.  A  third 
method  is  shown  by  the  corn  smut  which  may  infect  its  host  at  any 
time  by  entering  the  young  and  tender  parts  of  the  plant.  A  knowledge 
of  these  facts  is  important,  for  the  treatment  of  seeds  will  be  efficacious 
with  smuts,  which  infect  seeds,  while  it  would  be  useless  with  infection 
accomphshed  by  the  second  and  third  methods. 

Grain  smuts  cause  a  considerable  loss  to  the  farmer  every  year. 
Oat  smut,  it  has  been  estimated,  causes  a  loss  of  $10,000,000  per  annum 
in  the  United  States.  Smut  explosions  have  been  recorded  recently.  ^ 
In  the  wheat-growing  regions  of  the  Pacific  Northwest  in  the  summer  of 
1 914,  300  threshing  machines  were  blown  up  or  burned  by  smut  ex- 
plosions. Passing  into  the  cylinder  of  the  threshing  machine,  the  smut 
balls  were  broken  up  and  the  highly  combustible  smut  dust  oily  and 
dry  filled  the  interior  of  the  separator.  It  is  when  this  condition  ob- 
tains, that  the  explosions  and  flames  occur.  The  smut  dust  was  prob- 
ably ignited  by  static  electricity  in  the  cyHnder  of  the  threshing  machine. 
The  drier  the  conditions,  the  more  static  electricity  is  formed,  and  the 
easier  it  is  to  ignite  the  smut. 

The  family  Usttlaginace^  includes  eleven  American  genera.  Only 
three  genera  out  of  the  seven  will  be  considered  in  this  book.  They  are 
Ustilago,  Sorosporium  and  Tolyposporiiim.  The  genus  UsHlago,  of 
which  there  are  about  seventy-two  American  species,  is  distinguished 
from  the  other  two  less  important  genera  by  its  single  spores  which 
form  dusty  masses  at  maturity  without  any  kind  of  inclosing  membrane. 
Sorosporium  has  its  spores  agglutinated  into  balls  which  form  more  or 
less  dusty  masses.  The  spore  balls  are  usually  evanescent  and  the 
spores  are  very  dark.  The  spores  are  agglutinated  into  balls  in  Toly- 
posporium,  forming  more  or  less  dusty  spore  masses.  The  spore  balls 
are  rather  permanent,  the  spores  adhering  by  folds,  or  thickenings  of 
the  outer  coat. 

Family  2.  Tilletiace^. — The  name  Tilletia  which  is  that  of  an 
important  genus  (Fig.  63)  of  the  family  is  derived  from  Matthieu  Tillet, 
who  published  a  book  in  Bordeaux,  France,  in  1755.  The  sori  form 
dusty  spore  masses,  which  break  out  to  the  surface,  or  are  imbedded 
permanently  in  the  plant  tissues,  often  without  causing  any  malforma- 

1  AsHLOCK,  J.  L.:  Smut  Explosions.  The  Country  Gentleman,  April  10,  1915, 
P-  703- 


BASIDIA-BEARING    I'UNGI    (SMUTS) 


183 


Fig.  63. — Bunt  or  stinking  smut  of  wheat  (Tilletia  Irilici).  a.  Whole  head  af- 
fected with  smut;  h,  smutted  grains;  c,  normal  grains;  d,  smutted  grain  broken  to 
show  spores;  e,  normal  grain  divided  in  the  middle;  /,  chlamydospores  enlarged;  g, 
germination  of  a  spore.  {Draivings  by  Pool,  Venus  A.,  from  Bull.  135,  Set.  Ser.  141, 
Univ.  of  Tex.,  Nov.  15,  1909.) 


184  MYCOLOGY 

tion  of  these  parts.  In  germination,  a  promycelium  is  formed,  which 
usually  gives  rise  to  a  terminal  cluster  of  elongated  basidiospores,  or 
sporidia,  which  sometimes  bear  whorls  of  secondary  basidiospores. 
Sometimes  the  primary  sporidia  fuse  in  pairs,  and  these  with  or  without 
fusing  may  give  rise  to  infection  hypha?;  or  in  nutrient  media  to  a 
mycehum  bearing  dissimilar  secondary  sporidia  (aerial  conidia).  As 
in  the  preceding  family  the  hyphae  break  up  into  chlamydospores  which 
break  through  the  host  tissue,  as  a  sooty  mass  of  dust.  When  these 
chlamydospores  germinate,  they  give^  rise  to  an  undivided  basidium 
with  basidiospores  borne  at  the  apex  not  on  the  side,  as  in  the  preced- 
ing family.  This  is  the  principal  morphologic  difference,  as  the  two 
groups  of  smut  fungi  approach  each  other  so  closely  t^iat  in  external 
appearance  they  resemble  each  other.  Brefeld  described  the  structure 
and  life  history  of  Tilletia  tritici  {T.  caries),  the  bunt  of  wheat  very 
carefully.  In  England,  this  disease  of  the  wheat  plant  is  called  in 
various  districts  pepper  brand,  smut  balls,  bladder  brand,  stinking 
smut,  stinking  rust  (Fig.  63)  In  the  fields,  it  is  difficult  to  distinguish 
diseased  from  sound  wheat,  as  there  is  little  to  indicate  the  presence  of 
the  hidden  parasite,  but  it  excites  an  abnormal  development  of  chloro- 
phyll, so  that  the  spikes  of  the  affected  plants  are  usually  greener  than 
the  healthy  ones.  The  brand  spores  are  found  in  all  the  grains  of  a  single 
ear.  The  burst  grains  are  shorter  and  wider  than  healthy  ones  and 
pointed  toward  the  base.  When  cracked,  a  black  dust  is  discharged, 
which  under  the  microscope  is  seen  to  consist  of  reticulate-walled  spores 
of  an  olive-brown.  They  germinate  readily  and  even  after  eight  and  a 
half  years,  they  have  been  known  to  grow.  On  rubbing  the  black 
powdery  mass  between  the  fingers,  the  smell  of  herring  brine  is  given 
off,  and  this  decayed  fish  odor  has  originated  one  of  the  common 
names,  that  of  stinking  smut.  A  curved  unicellular  basidium  arises 
from  the  chlamydospore  on  its  germination.  This  produces  a  bundle 
of  elongated  condiospores,  or  basidiospores,  according  to  one's  bias. 
Sickle-shaped  secondary  conidiospores  arise  from  the  primary  kind. 
The  primary  conidiospores  may  unite  by  bridge-like  connections  so 
that  two  united  spores  look  like  the  letter  H.  Wheat  becomes  infected 
in  the  seedling  state,  the  spores  being  sown  with  the  grain,  and  the 
infection  hypha  which  enters  the  host  forms  a  mycelium  which  grows 
along  with  the  host  until  the  spores  break  out  again. 

Tilletia  is  the  most  important  genus.     In  it  the  sori  may  occur  in 


BASIDIA-BEARING   FUNGI    (sMUTS)  1 85 

various  parts  of  the  host,  usually  in  the  ovaries,  where  are  formed  a 
dusty  dark  spore  mass.  The  spores  are  simple,  separate  and  originate 
singly  at  the  ends  of  special  hyphse,  which  almost  disappear  through 
gelatinization.  The  spores  varies  in  size  from  i6/x  to  35/1.  Fifteen  out 
of  the  fifty-three  species  recorded  by  Saccardo  have  been  found  in 
North  America.  The  important  species  are  Tilletia  fcetens  bunt  or 
stinking  smut  of  wheat;  Tilletia  tritici  on  wheat;  Tilletia  horrida 
in  the  ovaries  of  cultivated  rice;  Tilletia  anthoxanthi  in  the  ova- 
ries of  the  sweet  vernal  grass,  Anthoxanthum  odoratum;  and  Tilletia 
Maclagani  on  a  wild  grass,  Panicum  vigatum.  Urocystis  cepulcB  is  the 
onion  smut;  Urocystis  occulta  on  the  stems  and  sheaths  of  rye;  Urocystis 
violcB  on  the  stems,  rootstocks,  petioles  and  leaves  of  violets,  Entyloma 
crastophilum  levis  on  such  grasses  as  Agrostis,  Poa,  E.  Ellisii  forms  pale 
white  spots  on  spinach  leaves  in  New  Jersey.  Entyloma  lineatum  grows 
on  wild  rice,  Zizania  aquatica;  Entyloma  thalictri  on  the  meadow  rice, 
Thalictrum  polygamum;  Entyloma  lobelice  or  Lobelia  inflata;  Entyloma 
nymphcece  on  the  leaves  of  Nuphar  advena  and  Nymphcea  odorata. 

The  species  of  Doassansia  mostly  grow  on  plants,  such  as:  S  a  git- 
tar  ia,  Potamogeton,  etc.,  growing  in  moist  situations.  Ten  species 
occur  in  North  America. 


BIBLIOGRAPHY  OF  THE  SMUTS 

Arthur,  J.  B.:  Rapid  Method  for  Removing  Smut  from  Seed  Oats.  Bull.  103, 
vol.  xii,  Agric.  Exper.  Stat.  Purdue  University,  March,  1905. 

Clinton,  G.  P.:  The  Smuts  of  Illinois  Agricultural  Plants.  Bull.  57,  Agric.  Exper. 
Stat.  Urbana,  March,  1900. 

Clinton,  G.  P.:  North  American  Ustilagineas.  Journal  of  Mycology,  8:  128-156, 
October,  1902 

Clinton,  George  P.:  North  American  Ustilagines,  Proceedings  Boston  Society 
of  Natural  History,  31:  504,  1904. 

Clinton,  George  P.:  The  Ustilaginea?,  or  Smuts,  of  Connecticut.  Bull.  .5, 
State  Geological  and  Natural  History  Survey,  1905. 

Clinton,  George  P.:  Ustilaginales  (Ustilaginaceae,  Tilletiaceae).  North  American 
Flora,  7,  part  I:  1-82,  Oct.  4,  1906. 

DiETEL,  P.:  Hemibasidii.  Die  naturhchen  Pflanzenfamilien,  I.  Teil,  Abt.  i, 
1900:  2-24. 

DuGGAR,  B.  M.:  Fungous  Diseases  of  Plants,  1909:  370-383. 

Eriksson,  Jakob:  Fungoid  Diseases  of  Agricultural  Plants,  191 2:  44-62. 

Garrett,  A.  O.:  The  Smuts  and  Rusts  of  Utah.  Mycologia,  II:  265-304,  No- 
vember, 1910. 


1 86  MYCOLOGY 

Gusspw,  H.  T.  Smut  Diseases  of  Cultivated  Plants.     Their  Cause  and  Control, 

Bull.  73,  Division  of  Botany,  Central  Experimental  Farm,  Ottawa,  Canada, 

March,  1913. 
Henderson,  L.  F.  :  Smuts  and  Rusts  of  Grains  in  Idaho.     Bull.  11,  Agric.  Exper. 

Stat.,  Idaho,  1898. 
Hitchcock,  A.  S.  and  Norton,  J.   B.  S.:  Corn  Smut.     Bull.  62,  Exper.  Stat., 

Kansas  State  Agricultural  College,  December,  1896. 
Massee,  George:  Text-book  of  Fungi;  1906:  313-325. 
Massee,  George  and  Ivy:  Mildews,  Rusts  and  Smuts:  a  Synopsis  of  the  Families, 

Peronosporaceae  Erysiphaceae,  Uredinacefe  and  Ustilaginacea?,  1913:  182-205. 
Smith,  Worthington  G.:  Diseases  of  Field  and  Garden  Crops,  1884:  245-262. 
Stevens,  F.  L.:  The  Fungi  Which  Cause  Plant  Disease,  1913:  298-323. 
Swingle,  Walter  T.:  The  Grain  Smuts:  How  They  Are  Caused  and  How  to 

Prevent  Them.  .  U.  S.  Farmers'  Bull.  75,  1898. 
Underwood,  L.  M.:  Moulds,  Mildews  and  Mushrooms,  1899:  81-85. 
VON  Tavel,  F.:  Vergleichende  Morphologic  der  Pilze,  1892:  109-120. 
von  Tubeuf,  K.:  Pflanzenkrankheiten,  1895:  289-340. 
VON  Wettstein,  Richard  R.  :  Handbuch  der  Systematischen  Botanik,  1911:  193- 

195- 


CHAPTER  XIX 
RUST  FUNGI 

Suborder  Uredine^. — -Usually  in  systematic  works  placed  as 
ORDER  UREDINALES.  The  fungi  belonging  to  this  suborder  are 
characterized  by  basidia  which  are  divided  either  by  transverse  or 
longitudinal  septae.  In  this  character,  they  are  contrasted  with  the 
EUBASIDII,  which  have  unseptate  basidia.  Including  the  rusts  this 
suborder  embraces  some  of  the  most  important  disease-producing 
fungi,  the  study  of  which  concerns  the  mycologist. 

The  uredineous  fungi  are  those  which  are  strictly  parasitic  and 
which  in  some  cases  are  so  specialized,  that  their  growth  is  confined  to 
the  species  of  a  single  host.  Those  fungi  in  which  the  different  stages 
of  the  life  cycle  are  passed  on  the  same  host  are  known  as  autoecious, 
while  those  which  grow  on  two  or  more  hosts  are  known  as  heteroecious. 
The  plant  on  which  the  final  stage  is  passed  is  called  the  final  host, 
while  the  other  plant  on  which  some  of  the  stages  occur  is  designated 
the  alternate  host.  So  speciahzed  is  the  nutrition  of  the  rust  fungi, 
that  they  never  have  been  grown  on  culture  media  off  the  host 
plants  on  which  they  live.  Hence,  they  are  obligate  parasites.  The 
myceUum  is  septate,  much-branched,  usually  ramifying  between  or  in 
the  walls  of  the  cells  and  sending  haustoria  into  the  cell  cavities. 
The  reproductive  spores  are  borne  in  more  or  less  definite  clusters,  or 
sori,  below  the  surface  of  the  host,  or  rarely  singly,  and  the  spores  are 
set  free  by  the  breaking  open  of  the  overlying  tissues  of  the  hosts. 

Five  different  kinds  of  spores  may  be  found  in  the  uredineous  fungi, 
but  they  are  not  all  present  in  every  genus  (Fig.  64).  The  final  spore 
form  is  known  as  the  teliospore,  or  teleutospore,  which  determines  the 
name  which  is  to  be  appHed  to  the  parasite.  Such  spores  are  borne 
in  a  sorus  known  as  a  teUum.  When  these  teliospores  germinate,  they 
produce  a  four-celled  promycelium  known  as  a  basidium,  and  this 
abstricts  sporidia,  or  more  properly  basidiospores,  which  are  minute, 
thin-walled  spores  without  surface  sculpturings.  These  are  succeeded 
by   spermogonia    (spermogonium),    which   are   now   called   by   most 

187 


I 88  MYCOLOGY 

American  mycologists,  pycnia  (pyciiium),  in  which  spermatia,  or 
pycniospores,  are  formed.  Pycnia  indicate  the  nature  of  the  life  cycle 
and  furnish  positive  characters  for  identification.  Arthur  has  shown 
that  if  pycnia  and  urediniospores  are  found  arising  from  the  same 
mycelium,  aecidia  do  not  occur  in  the  cycle;  and  if  pycnia  and  telio- 
spores  are  found  there  are  neither  uredinia  nor  secia  in  the  life  cycles. 
These  pycnospores  are  accompanied  or  succeeded  by  aeciospores 
(aecidiospores),  which  appear  in  the  cluster  cups,  or  aecia  in  long  chains. 
The  peridia  of  the  different  kinds  of  aecia  are  variable,  and  hence 


Fig.  64. — Spore  forms  of  wheat  rust,  Pucainia  graminis.  A,  Section  through 
barberry  leaf  showing  pycnia  on  upper  surface  and  secia  on  lower;  B,  two  uredinio- 
spores; C,  germinating  urediniospore ;  D,  teliosorus  showing  several  teliospores;  E, 
single  two-celledjteliospore ;  F,  germinating  teliospore  with  four-celled  basidium  and 
two  basidiospores;  G,  basidiospore  growing  on  barberry  leaf.     {Adapted  from  deBary.) 

mycologists  have  described  four  different  kinds  of  form  genera:  Cceoma 
=  peridium  absent;  Mcidiiim  =  cup-shaped  and  peridium  toothed; 
Roestelia  =  peridium  elongate  and  fimbriate;  Peridermium  =  peri- 
dium irregularly  split  and  broken.  Urediniospores  (uredospores) 
succeed  the  aeciospores  and  they  appear  in  sori  known  as  uredinia 
Curedinium).  Amphispores  are  special  forms  of  urediniospores  formed 
in  arid,  or  semi-arid  climates  and  usually  have  a  thick  cell  wall  and  a 
persistent  pedicel.  They  are  in  the  nature  of  a  resting  spore.  Meso- 
spores  are  exactly  of  the  same  nature  as  the  two-celled  teliospores,  but 
they  arise  merely  by  the  omission  of  the  last  nuclear  division,  and  hence. 


O  I  II     III     an  Eu-form 


RUST   FUNGI  189 

have  only  one  cell.  These  different  kinds  of  spores,  representing  stages 
in  the  life  histories  of  the  different  genera  and  species  of  rusts  are 
designated,  as  follows:  O  =  pycnium;  I  =  aecium;  II  =  uredinium; 
III  =  telium.  The  determination  of  the  presence  or  absence  of  these 
spores  in  the  various  life  histories  has  been  made  for  a  large  number  of 
rusts,  and  we  are  now  in  a  position  to  tabulate  the  results  of  this  study 
and  to  give  names  to  the  different  forms  of  rust  life  cycles  which  have 
been  found.     We  call  a  fungus  possessing: 

Auteu-form,  if  all  four  kinds  are  found  on  one  plant 

(Ex.  Puccina  Asparagi  on  Asparagus  officinalis). 
Hetereu-form,  if  O,  I  occur  on  one  species  and  II,  III 

}     on  another  (Ex.  Puccinia  gramiitis  is  on  wheat  and 

I    barberry). 
O  I  III     an    opsis-form   (Ex.  Gymnos porangimn  Jutiiperi-virginiance,  O,  I  on 

apple,  and  III  on  red  cedar). 
O      II     III     a  Brachy-form  (Ex.  Puccinia  suaveolens  on  Canada  thistle). 
[O]  III     a   Micro-form  pycnia   (spermogones)  sometimes  absent   (Ex.   Puc- 

cinia ribis  on  currant). 
A  Lepto-form  is  one,  of  whatever  kind,  in  which  the  teliospores 
grow  as  soon  as  mature  without  any  period  of  rest,  as  Puccinia  malva- 
cearuni  on  hollyhock.  W.  B.  Grove  in  his  "British  Rust  Fungi," 
page  40,  gives  a  diagram  which  represents  all  of  the  possible  life  cycles 
of  the  different  forms  of  rust  fungi.  It  is  reproduced  here  (Fig.  65). 
As  a  fungus  which  shows  a  complete  life  history  passed  on  two  dis- 
tinct host  plants,  we  will  take  the  black  rust  of  cereals,  Puccinia 
graminis  (Fig.  64),  first  carefully  studied  by  the  German  botanist, 
Anton  de  Bary,  in  1864-65.  It  infests  all  the  common  cereals,  wheat, 
rye,  barley  and  oats,  also  many  grasses.  It  appears  on  the  wheat 
plant,  when  the  host  is  about  ready  to  produce  its  spikes  of  flowers.  It 
appears  on  the  leaves  and  culms  of  the  wheat  plant,  as  orange-red 
lines,  which  represent  cracks  in  the  epidermis  of  the  host  exposing  the 
sori,  or  uredinia  filled  with  rust-red  spores,  urediniospores.  These 
summer  spores  are  yellowish  and  their  surface  spinulose  with  four  equa- 
torial germ  pores.  These  urediniospores  may  follow  each  other  on 
several  crops  during  the  early  summer.  This  summer  stage  is  succeeded 
by  the  autumn  stage  in  which  the  sori  become  filled  with  stalked, 
'  two-celled,  dark-colored  spores  with  thick  walls.  The  common  name 
of  this  stage  is  "black  rust."  Wintering  in  the  open  these  two-celled 
teliospores  germinate.  Each  of  the  two  cells  may  sprout  out  a  pro- 
mycelium,  or  only  one  may  do  so.     This  basidium  (promycelium)  is 


I  go 


MYCOLOGY 


upright  and  divided  transversely  into  four  cells,  each  of  which  cuts  off 
a  basidiospore.  These  basidiospores  are  blown  to  the  leaves,  twigs,  or 
fruits  of  the  barberry  where  a  mycelium  is  formed.  Later  pycnia 
(spermogonia)  appear  on  the  upper  side  of  its  leaf.  These  are  accom- 
panied by  round,  fringed  depressions,  the  cluster  cups  or  ascia,  which 
appear  in  the  spring  on  the  lower  side  of  the  leaves.  The  agciospores 
are  arranged  in  chains.  These  spring  spores,  aeciospores,  are  carried  to 
the  wheat  plant  where  they  induce  the  characteristic  rusted  appearance 


basidium 


teleutospore 


basidiospore 


uredospore 

mycelium 
secidiospore 

fusion-cell 

Fig.    65. — Relations  of  various  spore  forms  of  rusts  to  each  other.      {After  Grove,  W. 
B.,  The  British  Rust  Fungi,  19 13,  40.) 


of  the  cereal.  The  wheat  plant  is  not  killed  by  the  attack  of  the  fungus 
which,  however,  prevents  the  reserve  foods  from  being  properly  stored 
in  the  grains;  hence,  they  are  mushy  and  unfit  for  storage,  or  for  bread- 
making  purposes.  It  has  been  recently  shown  that  in  Australia  and  the 
plains  of  India,  where  the  barberry  is  unknown,  the  black  rust  of  wheat 
does  serious  damage.  Three  methods  are  open  to  the  wheat  rust  to 
winter  over:  (i)  The  fungus  may  winter  by  its  urediniospores,  (2)  by  a 
perennial  mycelium,  (3)  by  Eriksson's  mycoplasm.  Arthur,  in  Amer- 
ica, and  others  have  shown  that  it  winters  by  its  urediniospores,  or 


RUST    FUNGI  191 

amphispores,  as  they  have  been  termed  by  some,  but  in  conversation 
with  Arthur  he  insisted  that  the  perennating  spores  are  typical  uredinio- 
spores,  so  that  the  postulation  of  a  perennial  mycelium,  or  a  hibernating 
fungous  protoplasm  in  the  cells  of  the  grain  (mycoplasm)  is  unneces- 
sary. Eriksson  has  proved  that  in  Sweden  six  forms  of  Puccinia 
graminis  may  be  distinguished;  which  he  enumerates  as  follows: 

A.  Not  distinctly  fixed  (occasionally  going  over  to  other  forms  of 
grass):  (i)  f.  sp.  tritici  on  wheat  (seldom  on  rye,  barley  and  oats). 

B.  Distinctly  fixed  (firmly  confined  to  the  indicated  species):  (2) 
f.  sp.  secalis  on  rye,  barley  and  on  couchgrass,  Agropyron  repens,  Ely- 
mus  arenarius,  Bromus  secaUnus  and  others;  (3)  f.  sp.  avenae  on  oats 
arid  on  Avena  elatior,  Dactylis  glomerata^  Alopecurus  pratensis,  Milium 
efusuni  and  others;  (4)  f.  sp.  poae  on  Poa  compressa  and  P.  pratensis; 
(5)  f.  sp.  airae  on  Aira  ccespitosa  and  ^4.  hottnica;  (6)  f.  sp.  agrostis  on 
Agrostis  canena  and  A.  stolomfera.  An  oat  plant  infected  with  this  rust 
can  in  its  turn  infect  wheat,  rye,  barley  and  so  forth.  The  black  rust 
of  cereals  is  the  classic  example  of  an  heteroecious  rust. 

The  asparagus  rust,  Puccinia  asparagi,  may  be  used  to  illustrate  the 
life  history  of  an  autoecious  species.  All  the  spore  forms  are  pro- 
duced on  stems  and  twigs.  The  aecia  appear  in  long,  light  green  cush- 
ion-like areas,  which  are  short  cylindric  with  a  white  peridium.  The 
aeciospores  are  orange-colored  and  the  wall  is  hyaline.  The  pycnia 
appear  in  yellow  clusters  followed  by  the  aeciospores  in  early  sum- 
mer. The  uredinium  is  filled  with  yellowish-brown,  thick-walled  uredi- 
niospores  w'ith  three  or  four  germ  pores.  The  black  rust  stage  (telium) 
appears  later  in  the  season,  when  the  two-celled  stalked  teliospores  push 
out  from  beneath.  The  whole  life  cycle  is  passed  on  the  asparagus 
plant. 

Cytology  of  the  Rusts. — According  to  the  earlier  researches  of 
V.  H.  Blackman  (1904),  A.  H.  Christman  (1905),  O.  H.  Blackman  and 
Miss  H.  C.  Fraser  (1906),  Edgar  W.  Olive  (i9o8),Kurssanow  (1910)  and 
Dittschlag  (191 6),  supplemented  by  the  research  of  other  botanists,  a 
flood  of  light  has  been  thrown  on  the  nuclear  behavior  in  the  rusts,  and 
accordingly  on  their  sexuality,  or  non-sexuality.  Blackman  discovered 
in  Phragniidium  violaceum  (Fig.  66),  that  in  the  formation  of  the 
aecidium,  there  was  a  fusion  of  two  cells  by  which  the  nucleus  of  one 
passed  over  into  the  adjoining  cell.  In  the  formation  of  spores  the 
paired  nuclei  of  the  fusion  cell  divide  side  by  side  and  simultaneously 
(conjugate  division)  so  that  we  find  that  the  basal  cell,   the  aecio- 


192 


MYCOLOGY 


pores  and  intercalary  cells  all  have  two  nuclei,  which  are  not  sister 
nuclei.  The  upper  cell,  cut  off  from  the  fusion  cell,  is  the  secio- 
spore  mother  cell;  the  lower  grows  a  little  longer  and  then  divides  again 
in  the  same  way,  and  thus  a  vertical  series  of  aeciospore  mother  cells  is 
formed,  the  oldest  at  the  top.     Each  of  the  aeciospore  mother  cells. 


Fig.  66. — A,  Chain  of  young  jeciospores  of  Puccinia  caricis;  a,  fusion  tissue; 
b,  basal  (fusion)  cell  with  conjugate  nuclei;  c,  asciospore  mother-cell;  d,  intercalary 
cell;  e,  young  aeciospore;  B,  germinating  teciospore  of  P.  caricis;  C,  teliospore  of  P. 
caricis;  D,  formation  of  teliospores  of  P.  falcaria  {after  Dittschlag);  E,  development 
of  aecium  {after  Blackman)  of  Phragmidium  violaceum;  e,  epidermal  cell;  s,  sterile 
cell;  below  these  cells  a  nucleus  is  seen  migrating  into  the  adjacent  cell  /;  F  and  G, 
conjugation  of  two  female  cells  to  form  basal  cell  of  aeciospore  chain  {after  Ditlschlog). 
In  G  the  first  conjugate  division  is  just  completed.  {Adapted  frotn  Grove,  British 
Rust  Fungi.) 

as  soon  as  it  is  formed,  cuts  off  by  conjugate  division  a  small  cell  below, 
called  the  intercalary  cell;  this  sooA  disorganizes  and  disappears,  while 
the  other  portion  remains  as  the  aeciospore.  The  succeeding  uredinio- 
spores  have  two  nuclei  in  the  conjugate  condition  and  this  is  continued 
over  into  the  cells  of  the  young  teliospores  (Figs.  67  and  68).     Before 


RUST   FUNGI  193 

the  teliospore  reaches  maturity,  the  nuclei  fuse,  and  the  uninucleate 
condition  then  continues  again  until  the  formation  of  the  gecia.  In  the 
micro-  and  lepto-iorms,  which  have  no  aecium  or  uredinium,  we  find  that 
the  association  takes  place  at  points  in  the  ordinary  mycelium,  but 


Fig.  67. — Portion  of  a  section  of  cedar  apple  about  5  mm.  below  a  teliosorus. 
Note  (i)  Binucleate  intercellular  mycelium;  (2)  the  haustoria  in  various  stages  of 
development;  (3)  the  doubling  of  nucleoli  in  the  nuclei  of  some  of  the  parenchyma 
cells  of  the  host.  Material  collected  on  March  31.  {After  Reed,  H.  S.,  and  Crabill, 
C.  H.,  Techn.  Bull.  9,  Va.  Agric.  Exper.  Stat.,  May,  1915.) 

always  before  the  formation  of  the  teliospores.  Whether  the 
association  of  nuclei  in  the  ordinary  mycelium  takes  place  by  the 
migration  of  a  nucleus  from  one  cell  to  another,  or  whether  two  daughter 
nuclei  become  conjugate  in  one  cell  has  not  been  settled  definitely. 
The  pycnospores  are  probably  abortive  male  cells.  They  have  never 
13 


194 


MYCOLOGY 


Fig.  68. — Portion  of  a  teliosorus  of  cedar  apple  in  February  showing  mycelia 
stroma  and  the  binucleate  condition  of  the  cells  of  young  teliospores.  (After  Reed, 
H.  S.,  and  Crahill,  C.  H.,  Techn.  Bull,  g,  Va.  Agric.  Exper.  Stat.,  May,  IQ15.) 


teleutospore 


basidiospores 


uredospoTe. 


SPOEOPHYTE 

(2?i  generation) 


uredospore 


aecidiospore 
intercalary  cell 


GAMETOPHYTE 

(n  generation) 


spermatium 

$  gamete 


gametes 


fusion-cell 


Fig.  69. — Diagram  of  the  alternation  of  generations  of  a  typical  rust.     {After  Grove, 
W.  B.,  The  British  Rust  Fungi,  1913,  27.) 


RUST   FUNGI 


195 


been  known  to  germinate,  and  the  large  size  of  their  nuclei  suggests  that 
we  arc  dealing  with  male  cells. 

The  mature  tcliospore,  which  may  be  looked  upon  as  a  spore 
mother  cell,  has  a  single  fusion  nucleus.  "The  fusion  nucleus  is  large, 
round  and  (when  unstained)  perfectly  clear  and  homogeneous,  but  for 
its  nucleolus,  so  that  it  looks  like  a  vacuole;  it  occupies  almost  invari- 
ably the  middle  of  a  cell.  The  dense  chromatin  mass  is  loosened  out 
into  a  kind  of  spireme  which  becomes  shorter  and  thicker;  the  nuclear 
membrane  then  disappears,  and  the  spireme  thread  splits  longitudi- 
nally, though  the  splitting  is  often  indistinct.  It  then  divides  trans- 
versely into  segments  which  become  arranged,  or  strung  out,  on  a 
spindle  (sometimes,  but  more  rarely,  in  an  equatorial  plate) ;  then  the 
daughter  nuclei  are  formed  at  the  poles,  and  the  next  division,  which 
is  homotypic,  follows  immediately"  (Harper  and  Holden,  1903; 
Blackman,  1904).  These  nuclei  are  found  in  each  of  the  four  cells 
which  form  the  basidium,  and  ultimately,  they  pass  into  each  of  the 
four  basidiospores  which  are  uninucleate  and  haploid. 

The  alternation  of  generations  which  has  thus  been  determined  by 
the  various  cytologic  studies  of  recent  years  may  be  displayed  in  a 
diagram  adapted  from  Grove  (Fig.  69). 

The  same  life  cycle  may  be  represented  in  another  way. 

Basidiospore 


Gametophyte 
(w  generation) 


Sporophyte 
(2«  generation) 


Mycelium 


Pycnium 


Female  cells       Pycnospores 


Fusion  cell 

II 
.^ciospore  mother  cell 

.    ^  \ 

iEciospore       Intercalary  eel 

Urediniospore  (repeated) 

Teliospore 


Jicium 


0000 
4  Basidiospores 


196  MYCOLOGY 

EndophyUum  sempervivi  which  attacks  the  house  leek,  Semper- 
vivum,  and  causes  its  rosette  of  normally  spreading  leaves  to  stand 
erect,  shows  a  somewhat  different  condition,  which  has  led  to  the  sup- 
position that  it  represents  the  primitive  life  cycle  of  the  higher  ure- 
dineous  fungi.  Its  life  history  has  been  investigatecl  by  Hoffman 
(191 1).  The  spores  mature  on  the  house-leek  leaves  in  April  and 
May.  They  germinate  at  once  in  the  secidioid  telium  and  a  four- 
celled  basidium  is  formed;  hence,  the  spore  looks  like  an  seciospore 
and  partakes  of  the  nature  of  a  teliospore  and  may  be  called  an  secio- 
teliospore.  Each  basidium  produces  four  basidiospores  on  long  sterig- 
mata,  and  they  are  blown  to  the  leaf  of  a  house  leek,  where  they 
begin  growth  at  once  by  boring  through  the  cuticle,  and  the  mycelium 
then  grows  through  the  intercellular  spaces  of  the  host  sending  haus- 
toria  into  the  cells,  growing  down  to  the  base  of  the  leaf  and  into  the 
axis  up  to  the  growing  point,  where  it  perennates  until  the  following 
spring,  when  it  enters  the  freshly  formed  leaves,  which  become  yellow, 
longer  and  more  erect. 

Pycnia  are  formed  in  March  and  April  followed  by  aecio-telia, 
which  repeat  the  cycle.  Hoffman  has  established  the  most  interest- 
ing point  about  this  rust,  that  the  aecio-teliospore  chain  arises  from  a 
cell  produced  by  the  fusion  of  two  adjacent  cells  of  the  spore  bed 
after  the  manner  described  by  Christman  except  the  conjugating  cells 
were  not  in  any  definite  plane.  The  binucleate  secio-teliospores  then 
become  uninucleate  by  the  fusion  of  the  conjugate  nuclei.  The  for- 
mation of  the  basidiospores  from  these  oecio-teliospores  probably 
follows  a  reduction  division. 

Kunkel  (191 4)  has  shown  that  a  study  of  the  binucleate  seciospores 
of  CcBoma  nitens  during  germination  shows  that  they  become  uninu- 
cleate previous  to  the  production  of  the  promycelia.  The  normal  ger- 
mination of  the  aecio-teliospore  consists  in  the  pushing  out  of  a  germ  tube 
into  which  the  protoplasmic  contents  of  the  spore  passes.  The  nucleus 
which  travels  out  into  the  tube  divides  producing  two  nuclei  which  may 
divide  again  immediately  and  cell  division  may  follow  at  once,  but  in 
other  cases  the  four  nuclei  of  the  promycelium  (basidium)  may  be 
present  before  cross  walls  are  formed.  Ultimately,  four  cells  are  found 
filled  with  protoplasm  and  uninucleate.  The  basidiospore  arises  as  an 
enlargement  of  the  sterigma  and  the  nucleus  enters  when  it  is  one-half 
developed.  Cceoma  nitens  although  like  EndophyUum  sempervivi  in 
some  respects  is  more  primitive,  since  it  possesses  a  simpler  aecium. 


RUST   FUNGI  197 

Phylogeny  of  the  Uredine^  (Uredinales) 

In  looking  for  the  primitive  types  of  rust  fungi,  it  has  been  assumed 
by  some  mycologists,  that,  as  the  rusts  are  a  specialized  group  of  para- 
sites, the  most  primitive  forms  will  be  found  on  hosts  which  are  lowest 
in  the  phylogenetic  scale  of  the  higher  plants.  This  consideration 
would  place  Uredinopsis,  which  grows  upon  ferns,  as  one  of  the  primi- 
tive rusts,  while  many  of  the  more  advanced  types  of  Puccinia  are  found 
upon  the  Composite.  The  absence  of  a  germ  pore  is  considered  primi- 
tive, as  instance  its  absence  in  the  aecio-teliospore  of  EndophyUum. 
When  these  first  appeared,  they  were  numerous  and  indefinitely  scat- 
tered, while  in  the  higher  rusts,  they  are  reduced  in  number  and 
restricted  to  a  definite  part  of  the  cell  wall.  The  formation  and  ger- 
mination of  teliospores  approaches  that  of  the  smuts  a  more  primitive 
group,  hence  the  formation  of  a  basidium  and  basidiospores  must 
have  been  inherited  by  both  from  their  ancestors.  Now  among  the 
red  algge,  such  as  Grifjithsia,  the  sporophyte  bears  tetraspores,  these 
develop  into  a  thallus  which  bears  the  gametes.  Hence  one  would  look 
for  the  ancestors  of  the  UREDINE^  among  red  algge.  Again,  it  has 
been  suggested  that  the  female  cells  of  the  ascium  have  a  trichogyne, 
such  as  the  red  seaweeds  (Florideae)  possess.  In  the  rusts,  it  has  become 
abortive. 

The  Endophyllace^  are  considered  by  Grove  to  constitute  the 
starting  point  from  which  the  varied  forms  of  the  Pucciniace^  have 
been  derived.  In  EndophyUum,  we  have  seen  that  the  seciospore,  which 
is  the  product  of  the  fusion  cell,  is  also  the  teliospore  from  which  the 
basidium  and  basidiospores  arise.  The  aecium  is  accompanied  by  the 
pycnium  here.  The  first  stage  of  evolution  was  the  separation  of  this 
spore  form  into  two:  one  the  geciospores,  germinating  like  conidio- 
spores;  the  other,  the  teliospore,  germinating  with  the  formation  of  a 
basidium  and  basidiospores.  Pucciniopsis  suggests  these  stages.  The 
summer  spores  are  probably  modified  geciospores  formed  as  a  device 
for  repeating  the  spore  generations  without  the  intervention  of  another 
fusion  cell.  The  fusion  of  the  two  nuclei  in  the  teliospore  is  from  a 
cytologic  standpoint  paralleled  by  a  similar  fusion  in  the  BASIDIO- 
MYCETALES,  for  a  division  into  four  basidiospores  follows  in  both 
cases,  although  the  mechanism  is  different.  The  paired  condition 
of  the  nuclei  found  in  the  ascogenous  hyphae  of  the  ASCOMYCETALES, 
such  SLsPyronema  confluens  investigated  by  Claussen  (1912),  and  in  the 


198  MYCOLOGY  • 

formation  of  the  ascus,  the  two  nOn-sister  nuclei  fuse  after  which  the 
fusion  nucleus  divides,  the  first  division  being  heterotypic  (meiotic, 
reducing,  possessing  synapsis  and  diakinesis  stages),  and  the  two  fol- 
lowing ones,  which  result  in  the  formation  of  eight  ascospores,  are 
homotypic.  From  this  point  of^view,  the  ascus  is  a  spore  mother  cell 
comparable  to  the  teliospore  of  the  rust  fungi,  but  forming  an  octad, 
not  a  tetrad  of  spores.  The  probable  phylogeny  and  relationship  of 
the  Uredine^  to  the  other  groups  has  been  set  forth  in  a  family  tree 
by  Grove. 

Arthur,  who  has  studied  the  rusts  carefully  for  many  years,  pro- 
posed at  the  International  Congress  of  Botanists  held  in  Vienna  in 
1905  an  arrangement  of  the  famihes,  genera  and  species  of  the  rusts, 
which  differs  materially  from  the  older  classifications. 

As  this  classification  of  Arthurs  has  not  been  elaborated  in  detail, 
it  has  been  considered  best  to  follow  the  arrangement  of  families,  sub- 
families and  genera  given  in  Engl er  and  Gilg's  "Syllabus  der  Pflanzen- 
familien"  (7th  Edition,  191 2)  as  following  the  conservative  and 
older  treatment. 

Family  Endophyllace^. — The  teliospores  are  abstricted  suc- 
cessively in  long  rows  and  are  surrounded  by  a  peridium  which  is 
formed  like  that  of  a  typic  aecidium  of  Puccinia  from  the  peripheral 
cell  rows,  but  is  sometimes  less  strongly  developed.  These  teliospores 
are  perhaps  more  correctly  called  aecio-teliospores,  as  they  are  separated 
from  each  other  by  intercalary  cells  like  true  seciospores  and  arise 
from  a  fusion  cell,  but  they  germinate  by  the  formation  of  a  basidium 
and  basidiospores  like  true  teliospores.  The  germ  pores  are  impercep- 
tible and  the  spore  wall  is  colored.  Pycnia  are  present  and  both  kinds  ■ 
of  sori  are  subepidermal. 

Endophyllum  sempervivi  lives  parasitically  on  the  house  leek,  Sem- 
pervivum  tedoruni,  and  several  other  species  of  Sempervivum  in  Europe 
from  April  to  August.  It  has  been  proved  by  de  Bary,  Hoffmann  and 
others,  that  the  basidiospores  produced  by  the  secio-teliospores  infect 
the  leaves  of  the  house  leek  and  from  them  arises  a  mycehum  which 
lives  over  the  winter  in  the  stem.  The  following  spring,  it  forms 
pycnia  and  secio-teliospores  and  the  affected  leaves  are  more  erect 
than  normal  ones,  twice  as  long,  narrower  and  yellowish  at  the  base. 

Family  MelampsoracetE.— The  tehospores  are  unstalked,  one-  to 
four-celled,  but  placed  singly  on  dilated  hyphie  in  the  tissues  of  the 


RUST    FUNGI  199 

host,  or  arranged  side  by  side  in  flat  crusts.  Germination  of  the  teHo- 
spore  results  in  the  formation  of  a  four-celled  basidium,  each  cell  of 
which  forms  a  single  basidiospore.  The  secium  is  typically  without  a 
peridium,  hence,  a  cseoma  and  the  urediniospores  appear  in  long  chains 
without  a  peridium,  or  arising  singly,  and  then  mostly  surrounded 
by  the  peridium,  or  mixed  with  paraphyses. 

The  genus  Melampsoropsis  includes  fungi  whose  teliospores  are  in 
cushion-like  layers,  which  break  through  the  epidermis  of  the  host. 
M.  ledi  has  its  teliospores  on  Ledum  and  its  aecia  on  the  spruce,  Picea 
excelsa,  in  Europe,  and  on  P.  rubra  in  this  country.  The  secia  of  Cronar- 
tium  have  a  broad,  inflated  irregularly  torn  peridium.  The  uredinium 
is  enclosed  in  a  hemispheric  peridium,  which  opens  at  the  summit  by  a 
narrow  pore.  Its  teliospores  are  abstricted  in  long  chains  and  remain 
united  into  cylindric  columns,  which  are  horny  when  dry.  The 
European  C.  asclepiadeum  has  its  gecia  on  the  branches  of  Plnus  sihestris 
in  May  and  June,  and  its  urediniospores  and  teliospores  on  PcBonia 
officinalis  in  gardens,  as  also  on  Vincetoxicum,  Cynanchum  and  Verbena. 
C.  quercmim  has  its  aecia  on  Pin  us  and  its  urediniospores  and  teliospores 
on  at  least  twenty  species  of  oak  in  North  America.  C.  ribicola  is  a 
dangerous  parasite  called  the  white  pine  blister  rust  and  against  it  the 
United  States  Government  has  an  active  quarantine.  Its  aecium  is  con- 
fined to  the  five-leaved  pines,  one  of  which  is  Pinus  strobus,  our  eastern 
white  pine.  These  are  found  in  the  months  from  March  to  June.  The 
urediniospores  and  teliospores  grow  on  the  currants,  Ribes  nigrum  and 
R.  rubrum.  The  fungi  of  the  genus  Melampsora  are  mostly  heteroecious. 
There  are  seven  species  recorded  for  North  America.  Of  these  Melam- 
psora meduscB  causes  the  poplar  rust.  The  aecium  occurs  on  the  larch, 
Larix,  and  its  urediniospores  and  teliospores  on  Populus  deltoides,  P. 
tremuloides  and  P.  balsamifera.  Calypfospora  is  a  genus  of  rusts,  the 
life  history  of  which  has  been  investigated  by  Hartig,  Kuhn  and 
Bubak.  In  July  to  September,  the  teliospores  appear  on  the  stems  of 
Vaccinium  vitis-idcBa,  where  the  stem  becomes  swollen  and  elongated 
and  at  first  of  a  pink  color  passing  to  brown.  It  occurs  on  other  species 
of  Vaccinium,  including  V.  pennsylvanicum  in  the  United  States.  The 
aecia  are  found  in  Europe  on  leaves  of  Abies  pectinata  and  in  America 
on  A .  balsamea. 

Family  Coleosporiace^. — The  aecium  in  this  family  has  a  perid- 
ium.    The  flattish,  linear   pycnia   are    subepidermal  dehiscing  by  a 


MYCOLOGY 


slit.  The  teliospores  consist  of  four  superimposed  cells.  There  is  a 
North  American  species  of  this  family,  Gallowaya  pini  (formerly  Coleo- 
sporium  pini),  which  has  teUospores  only  and  these  on  the  leaves  of 
Pinus  inops,  i.e.,  on  trees  of  the  same  order  on  which  Coles porimn  has 


A 

Fig.  70. — A-D,  Uromyces  pisi.  A,  Ascidia  on  deformed  leaves  of  Euphorbia 
cyparissias;  B,  ascidia  enlarged;  C,  teliosori  on  leaves  of  Pisum  sativum;  teliosori 
enlarged;  E  and  F,  Uromyces  Irifolii  on  Trifolium  hybridum.  {After  Dietel,  Die 
natiirlichen  Pflanzenfamilien  I.  lA**,  p.  55.) 

its  aecia.  In  Coleosporium,  the  teUospores  are  adherent  closely  with  a 
rounded,  thickened,  gelatinizing  pore.  The  long  sterigmata  bear 
large,  ovate,  flattened  sporidia.  The  orange  rust  of  asters  and  golden 
rods,^'C.  solidaginis  is  reported  to  cause  a  sickness  of  horses,  some- 


RUST   FUNGI  20I 

times  resulting  in  the  death  of  the  animals.  Its  urediniospores  and 
teliospores  are  on  compositous  plants  and  its  aecial  stage  on  the  pitch 
pine,  Pinus  rigida,  this  stage  being  known  in  the  older  books  as 
Peridermium  acicolum.  The  species  of  the  genus  are  all  heteroecious, 
and  ascial  stages,  whenever  found,  occur  on  species  of  Pinus  and 
are  referable  to  the  form  genus  Peridermium.  Arthur  and  Kern 
enumerate  twenty-seven  species  of  Peridermium,  ranging  from  Mexico 
to  Alaska,  and  from  the  Atlantic  to  the  Pacific  coasts.  The  species 
are  all  secia  of  species  belonging  to  tehal  genera,  but  they  cannot 
be  always  satisfactorily  assigned  because  of  incomplete  knowledge 
regarding  them.  The  genus  Peridermium  embraces  all  aecial  forms 
possessing  peridia,  inhabiting  the  Pinace^  and  Gnetace^.  Only 
three  of  the  twenty-seven  American  species  have  been  associated  with 
telial  forms  as  follows: 

Peridermium  pini  connected  with  Coleosporium  campanulcc  on 
Campanula. 

Peridermium  cerebrum  connected  with  Cronartium  on  oak. 

Peridermium  elatinum  connected  with  Melampsorella  cerastii. 

Family  Pucciniace^. — In  this  family,  the  teliospores  usually  con- 
sist of  a  single  cell,  or  a  vertical  row  of  superimposed  cells  sometimes 
united  into  a  small  bead-like  cluster.  The  teliospores  are  borne  on  a 
simple,  or  a  compound  pedicel.  The  urediniospores  are  single,  on 
hyaline,  deciduous  stalks.  The  secia  usually  have  a  peridium.  The 
most  important  genera  of  the  family  are:  Uromyces,  Puccinia,  Gymno- 
sporangium,  Gymnoconia  (Fig.  71)  and  Phragmidium. 

The  rusts  belonging  to  the  genus  Uromyces  have  one-celled  winter, 
or  teliospores,  which  are  egg-shaped,  individually  separated  and  massed 
in  small,  open  spore  groups.  The  important  pathologic  species  are  the 
clover  rust,  Uromyces  trifolii;  the  rust  of  beans,  U .  appendiculata;  beet 
rust,  U.  betcB;  carnation  rust,  U.  caryophyllinus  (Fig.  70).  The  largest 
genus  of  the  rusts,  Puccinia,  has  usually  two-celled  teliospores,  although 
unicellular  ones  may  occur  in  some  species.  The  principal  cereal  or 
grain  rusts  may  be  enumerated  first,  as  they  are  fairly  well  known, 
owing  to  the  researches  of  Eriksson  and  others: 

Black  Rust  of  Cereals,  Puccinia  graminis  (Fig.  64)  with  its  aecium 
on  the  barberry,  Berberis  vulgaris.  Six  forms  of  this  species  may  be 
distinguished:  (i)  f.  sp.  h-itici  on  wheat  (seldom  on  rye,  barley 
and  oats);  (2)  f.  sp.  secalis  on  rye,  barley  and  couch  grass,  Agropyron 


202  MYCOLO&Y 

repens,  Elymns  arenarius,  Bromus  secalimis  and  others;  (3)  f.  sp. 
avencB  on  oats  and  Avena  elqtior,  Dactylis  glomerata,  Alopecurus  praten- 
sis,  Milium  efusum,  etc.;  (4)  f.  sp.  po(B  on  Foa  compressa  and  P.  praten- 
sis;  (5)  f.  sp.  airce  on  Aira  ccBspitosa  and  A.  hottnica;  (6)  f.  sp.  agrostis  on 
Agrostis  canina  and  A.  stolonijera. 

Brown  Rust  of  Rye,  Puccinia  dispersa,  with  its  cluster  cups  on 
Anchusa  arvensis  and  A.  officinalis. 

Crown  Rust  of  Oats,  Puccinia  coronifera,  with  its  secium  on  the 
buckthorn,    Rhamnus    cathartica.     Of   this    species    there    are    eight 


Fig.  7 1 . — A-C,  Gymnoconia  interstitialis.  A ,  ^cidia  on  leaf  of  Rubus  canadensis; 
B,  piece  of  leaf  enlarged;  C,  teliospore;  D,  teliospore  oi  Sphenospora  pallida,  500/  i. 
{After  Dieiel:  Die  naturlichen  Pflanzenfamilien  I.  lA**,  p.  70.) 


speciahzed  forms,  as  follows:  (i)  f.  sp.  avencB  on  oats;  (2)  f.  sp.  alope- 
curi  on  Alopecurus  pratensis;  (3)  f.  sp.  festuccd  on  Festucas;  (4)  f.  sp. 
lolii  on  rye  grass,  Lolium  perenne;  (5)  f.  sp.  glycericB  on  Glyceria  aqua- 
tica;  (6)  f.  sp.  agropyri  on  Agropyron  repens;  (7)  f.  sp.  epigm  on  Cala- 
magrostis  epigeios;  (8)  f.  sp.  hold  on  Holcus  lanatus. 

Crown  Rust  of  Grasses,  Puccinia  coronata,  with  its  aecium  on  Rham- 
nus frangula.  Three  special  forms  of  this  rust  are  known:  (i)  f.  sp. 
calamagrostis   on  Calamagrostis  ariindinacea;    (2)  f.  sp.  phalaridis  on 

1  Arthur,  J.  C.  and  Kern,  F.  D.:  North  American  Species  of  Peridermium, 
Bull.  Torr.  Bot.  Club,  33:  403-43''^i  iyo6. 


RUST  FUNGI 


203 


Phalaris  armidinacca;  (3)  f.  sp.  agrostis  on  Agrostis  vulgaris  and  A, 
sfolonifera. 

Yellow  Rust  of  Wheat,  Puccinia  glumarum,  without  any  known 
aecial  stage.  It  has  according  to  Eriksson  the  following  specialized 
forms:  (i)  f.  sp.  tritici  on  wheat;  (2)  f.  sp.  secalis  on  rye;  (3)  f.  sp. 
hordei  on  barley;  (4)  f.  sp.  Elymi  on  elymus  arenarius;  (5)  f.  sp. 
agropyri  on  couch  grass,  Agropyron  repens. 


Fig.   72. — Hollyhock  rust,  Puccinia  tnalvacearum.      {Nantucket,  August  19,    igis.)' 


Brown  Rust  of  Wheat,  Puccinia  triticina,  with  aecia  unknown. 

Dwarf  Rust  of  Barley,  Puccinia  simplex. 

Timothy  Rust,  Puccinia  phlei-pratensis.  Experiments  to  get  this 
form  to  infect  barberry  leaves  have  met  with  indifferent  success. 

Chrysanthemum  Rust,  Puccinia  chrysanthemi,  on  leaves  of  Chry- 
santhemum  sinensc  in  greenhouses  all  the  year  round. 


204  MYCOLOGY 

Dandelion  Rust,  Puccinia  iaraxaci,  on  the  dandelion  Taraxacum 
officinale,  rather  common  in  Europe,  North  America,  Japan  and  the 
East  Indies. 

Reed  Grass  Rust,  Puccinia  phragmitis,  with  aecia  on  Rumex  crispus, 
R.  ohtusif alius  and  urediniospores  and  teliospores  on  reed  grass  Phrag- 
mites  communis. 


Fig.  73. — Roeslelia  aurantiaca  on  fruit  oi  Amelanchier  intermedia  corresponding 
to  Gymtiosporangium  clavipes  on  red  cedar.  (Shelter  Island,  New  York,  July  16, 
•1915-) 


Ash  Rust,  Puccinia  fraxinata,  on  leaves  and  petioles  of  ash  and 
uredinospores  and  teliospores  on  salt  grass,  Spartina  Michauxiana. 

Asparagus  Rust,  Puccinia  asparagi,  develops  all  of  its  spore  forms 
on  the  cultivated  asparagus. 

Violet  Rust,  Puccinia  violce,  is  parasitic  on  about  forty-six  different 


RUST   FUNGI 


205 


species  of  violetsjn\\sia/  Europej'^North^and  South  America.     It 
autoecious. 


m 

—.J 

il 

H|^ 

I'i 

1 

Fig.  74. — Witches'  broom  caused  by  Gymno-  Fig.    75. — A,  Protruding    fili- 

sporangium  Ellisii.      {After  Harshberger,  Proc.       form    horns  of   the    rust   fungus, 
Acad.  Nat.  Sci.  Phila.,  May,  1902.)  Gymonsporangiiim  Ellisii  on  white 

cedar;    B,   teliospore.      (May  27, 
1916.) 

Mint  Rust,  Puccinia  menthcB,  is  also  an  autoecious  rust. 
Maize  Rust,  Puccinia  sorghi,  is  widely  distributed  in  maize-growing 
countries.     Its  secia  are  less  common  on  various  species  of  O.xalis. 


2o6 


MYCOLOGY 


Rust  of    Stone  Fruits,  Puccinia  pruni-spinQsa:,  occurs  on  various 
species  of  the  genus  Prunus  in  the  southern  and  central  United  States. 


Fig.  76.- — Fully  expanded  cedar  apple  on  red  cedar.  Long  yellow  teliosori  as 
finger-like  projections  are  seen.  (After  Jones  and  Barlholomew,  Bull.  257,  Agric. 
Exper.  Stat.,  Univ.  Wise,  July,  1915.) 


The  secial  stage  occurs  on  Anemone   and   Hepatica,  and  is  known  as 
jEcidium  punctatum. 

Hollyhock  Rust,  Puccinia  malvacearum  (Fig.  72),  is  found  over  the 
world,  where  the  hollyhock,  Althcea  rosea,  is  grown. 


RUST   FUNGI 


207 


Fig.  77. — Longitudinal  section  of  a  partly'gelatinous  teliosorus'after  the  exten- 
sion of  the  tentacles.  (After  Reed,  H.  S.,  and  Crahill,  C.  H.,  Techn.  Bull.  9,  Va. 
Agric.  Exper.  Slat.,  May,  1915.) 


208 


MYCOLOGY 


Belonging  to  the  genus  Gymnoconia  (Fig.  92)  is  the  orange  rust 
of  raspberry  and  blackberry  which  is  found  throughout  the  United 
States  and  Canada.     It  is  also  widely  distributed  in  Europe  and  Asia. 

The  genus  Phragmidium,  which  is  confined  entirely  to  plants  of  the 
rose  family,  is  autoecious.  Warts  are  formed  on  the  teliospores  by  the 
contraction  of  an  outer  gelatinous  layer  which  with  a  rigid  middle 
lamina  and  the  arrangement  of  the  germ  pores  distinguishes  Phrag- 


FiG.  78. — Teliospores  of  cedar  apple  showing  germination  with  formation  of 
basidia  (promycelia)  and  basidiospores  (sporidia).  {After  Reed,  H.  S.,  and  Crabill, 
C.  H.,  Techn.  Bull.  9,  Va.  Agric.  Exper.  Stat.,  May,  1915.) 


midium  from  neighboring  genera.  The  teliospores  are  two-  to  several- 
celled  by  transverse  septa.  An  important  species  is  the  Rust  of  Roses, 
Phragmidium  subcorticium,  which  has  a  spindle-shaped  teliospore  with 
six  to  eight  cells. 

Gymnosporangium  is  a  genus  of  heteroecious  rusts  the  secia  of  which 
occur  on  Rosacea  (except  one  on  Hydrangeac^  and  one  on  Myri- 


RUST   FUNGI 


log 


cace.e)  while  the  three-,  four  or  five-celled  teliospores  are  found 
on  CupRESSiNEiE  {Chamcecyparis ,  Cupressus,  Juniperus,  Libocedrus). 
One  autoecious  species  is  G.  bermudianum  which  produces  both  its 
ascia  and  telia  on  junipers  (/.  bermudianum) .  Kern  gives  thirty-two 
species  as  the  number  for  North  America  and  in  vol.  7,  North  American 
Flora,  part  3,  pages  188-190,  gives  a  useful  key  for  the  identification 
of  the  species. 

Gymnosporangium  botryapites  causes  fusiform  swellings  on  the  white 
cedar,  Chamcecy parts  thyoides,  on  which  swellings   the  two-   to  four- 


FlG. 


79- — Cedar  rust  on   apple,  roestelia  stage  with  pustules.^    {After  Jones   and 
Bartholomew,  Bull.  257,  Agric.  Exper.  Stat.,  Univ.  Wise,  July,  1915.) 


celled  teliospores  are  formed.  The  aecia  occur  on  two  species  of  shad 
bush:  Amelanchier  canadensis  and  A.  intermedia  (Fig.  73). 

In  Gymnosporangium  nidus-avis,  the  telia  arise  from  a  perennial 
mycelium  which  often  dwarfs  the  young  shoots  and  causes  bird's-nest 
distortions  in  which  usually  there  is  a  reversion  of  the  leaves  to  the 
juvenile  form,  sometimes  causing  gradual  enlargements  in  isolated 
areas  on  the  larger  branches  of  Juniperus  virginiana  with  gecia  on 
several  species  of  Amelanchier  (Fig.  73). 

Juniperus  communis  is  the  host  of  the  telial  stage  of  G.  clavaricBforme, 
which  appears  on  long  fusiform  swellings  of  various-sized  branches, 
14 


MYCOLOGY 


scattered,  or  aggregated  and  its  aecia  on  seven  species  of  Amelanchier , 
one  each  of  Aronia  and  Cydhnia. 

Gymnosporangium  Ellisii  (Figs.  74  and  75)  in  its  telial  form  distorts 
the  younger  branches  of  the  white  cedar,  ChamcBcyparis  thyoides,  pro- 


FiG.  80. — Roestelia,  or  aecia  on  apple  leaf.      {After   Giddings   and   Berg,  Bull.  257, 
Agric.  Exper.  Stat.  Univ.  Wise,  July,  1915.) 


ducing  numerous  fasciations.  The  aecia  and  pycnia  of  this  fungus 
are  on  Myrica.  Gymnosporangium  globosiim  is  remarkable  in  forming 
aecia  on  eighty-five  different  species  of  hawthorn,  Cratcegus,  while  its 


RUST    FUNGI 


teliospores   appear   on   irregular   spheric   swellings   or  excrescence   on 
Jitiiiperus  virginiana. 

The    mycelium   of    G.  jimiperi-virginiance    is  annual,  or  biennial, 
producing  globose  swellings  known  as  cedar  apples  on  the  leaves  of  the 


— ;: 3= 5 

■        * 

j*  'it J 

p 
*;,^^^^ 

Fig.  8i. —  Alagnified  view  of   apple  rust  roestelia,   or  aecia.      (After  Jones  and 
Bartholomew,  Bull.  257,  Agric.  Exper.  Slat.  Univ.  Wise,  July,  1915.) 

red  cedar,  Juniperus  virginiana.     The  cluster  cups  appear  on  the  leaves 
of  native  species  of  apples  {Mains). 

The  most  important  publication  dealing  with  this  disease  and  giving 


212  MYCOLOGY 

a  copious  bibliography  is  one  by  HowardL.  Reed  and  C.  W.  Crabill  issued 
as  Technical  Bulletin  9  (May,  1915)  by  the  Virginia  Agricultural  Experi- 
ment Station.  The  106  pages  of  text  are  devoted  to  a  careful  considera- 
tion of  all  aspects  of  the  disease,  which  is  prevalent  throughout  the 
geographic  range  of  the  red  cedar.  The  aecia  are  found  on  the  apple 
and  were  originally  described  as  RoesteUa  pyrata  (Schw.)  Thaxter, 
and  frequently  the  apple  stage  is  known  as  the  RoesteUa  stage  (Fig. 
81).  Infection  of  the  leaves  (Fig.  80)  and  fruit  is  only  possible 
during  their  undeveloped  condition  and  not  all  varieties  of  apple  are 
susceptible.  Some  are  rust  free.  Such  are  Early  Harvest,  Golden 
Pippin,  Winesap,  while  the  badly  affected  varieties  are  Grimes  Golden, 
Smokehouse   and   York  Imperial.     The  aeciospores  are  dark  brown, 


Fig.  82. — Diagram  (left)  of  aecium  (roestelia)  of  apple  rust;  right,  three  Kcio- 
spores  from  the  cup  highly  magnified.  {AfUr  Jones,  L.  R.,  and  Bartholomew,  E.  T.. 
Bull.  257,  Agric.  Exp.  Stat.,  Univ.  Wise,  July,  1915.) 

minutely  pitted  and  almost  spheric  with  thick  walls  and  granular  con- 
tents. The  first  aecia  (Figs.  81  and  82)  become  mature  during  the 
month  of  July  and  viable  spores  are  produced  in  large  numbers  during 
this  and  the  following  two  months  (Fig.  83).  This  is  the  period  of 
infection  of  the  red  cedar,  and  the  mycelium  formed  from  these  spores 
remains  dormant  in  the  cedar  leaves  until  the  following  spring,  when 
the  cedar  apple  (Fig.  76),  or  gall,  is  formed  out  of  the  parenchyma 
of  the  red  cedar  leaf  (Fig.  161).  Into  the  gall  a  vascular  strand  extends. 
The  surface  of  the  galls  becomes  papillate  and  in  May  these  papillae 
enlarge  into  gelatinous  horns,  or  teliosori  (Fig.  77),  made  up  of  the 
agglutinated  stalks  of  numerous  teliospores  (Fig.  77),  which  are  two- 
celled  and  measure  46  to  63/x  by  15  to  20/x  (Fig.   78).     These  telio- 


RUST   FUNGI 


213 


spores   on    germination   produce    a    four-celled   basidium    (Fig.  78), 
or  promycelium,  from  which  are  cut  off  basidiospores,  which  infect  the 


partially  developed  apple  leaves,  or  apple  fruits  (Fig.  79).     The  dis- 
ease apparently  does  little  damage  to  the  red  cedar  trees,  but  the 


214  MYCOLOGY 

aecial  stage  devastates  the  apple  orchards  found  in  proximity  to  red 
cedar  trees  infected  with  the  rust.  Destroying  the  red  cedar  trees 
seems  to  be  the  only  feasible  plan  of  combating  the  disease. 

BIBLIOGRAPHY  OF  THE  RUSTS 

Arthur,  J.  C:  Cultures  of  Uredineje.  I  (1899),  Botanical  Gazette,  29:  268-276; 
II  (1900  and  1901),  Journal  of  Mycology,  8:  51-56;  IV  (1903),  Journal  of  My- 
cology, 10:  8-21;  V  (1904),  Journal  of  Mycology,  11:  50-67;  VI  (1905),  Journal 
of  Mycology,  12:  11-27;  VII  (1906),  Journal  of  Mycology,  13:  189-205;  VIII 
(1907),  Journal  of  Mycology,  14:  7-26;  IX  (1908),  Mycologia,  i:  225-256;  X 
(1909),  Mycologia,  2:  213-240;  XI  (1910),  Mycologia,  4:  7-33;  XII  (191 1), 
Mycologia,  4:  49-65;  XIII  (1912,  1913  and  1914),  Mycologia,  7:  61-89; 
XIV  (1915),  Mycologia,  8:  125-141. 

Arthur,  J.  C.  and  Holway,  E.  W.  D.:  Description  of  American  Urcdinea;.  Bull. 
Lab.  Nat.  Hist,  of  State  Univ.  of  Iowa,  I,  3:  44-57;  Hj  4:"377-402;  III,  5: 171- 

193;  IV,  5:311-334- 

Arthur,  J.  C.:  Clue  to  Relationship  among  Hetercecious  Plant  Rusts.     Botanical 

Gazette,  33:  62-66,  January,  1902. 
Arthur,  J.  C:  The  Uredineae  Occurring  upon  Phragmites,  Spartina  and  Arundinaria 

in  America.     Botanical  Gazette,  34:  1-20,  July,  1902. 
Arthur,  J.  C:  Problems  in  the  Study  of  Plant  Rusts.     Publ.  22,  Botanical  Society 

of  America,  Dec.  31,  1902,  1-182. 
Arthur,  J.  C:  Taxonomic  Importance  of  the  Spermogonium.     Bui.  Torr.  Bot. 

Club,  31:  125-159,  March,  1904. 
Arthur,  J.  C:  Terminology  of  the  Spore  Structures  in  the  Uredinales.      Botanical 

Gazette,  39:  219-222,  March,  1905. 
Arthur,  J.  C:  Amphispores  of  Grass  and  Sedge  Rusts.     Bull.  Torr.  Bot.  Club,  ^,2: 

35-41,  1905. 
Arthur,  J.  C.  and  Kern,  F.  D.:  North  American  Species  of  Peridermium.     Bull. 

Torr.  Bot.  Club,  33:  403-438,  1906. 
Arthur,   J.    C:  Eine  auf  die  Struktur  und  Entwicklungsgeschichte  begriindete 

Klassifikation  der  Uredineen.  Rusultats  Scientifique  du  Congres  international 

de  Botanique  Wien,  1905:  331-348,  1906. 
Arthur,  J.  C:  New  Species  of  Uredinese.     Bull.  Torr.  Bot.  Club,  I,  23:  661-666, 

December,   1901;  II,   24:  227-231,  April,   1902;  III,  31:  1-8,  January,   1904; 

IV,  33:  27-34,  1906. 
Arthur,  Joseph  C:  Uredinales.     Coleosporiaceas,  Uredinaces,  ^cidiace^  (pars). 

North  American  Flora,  7,  part  2,  1907;  /Ecidiacese  (continuatio),  7,  part  3,  191 2. 
Arthur,  J.  C:  On  the  Nomenclature  of  Fungi  Having  Many  Fruit  Forms.     The 

Plant  World,  8:  71-76;  99-103. 
Blackman,  H.  v.:  On  the  Fertilization,  Alternation  of  Generations,  and  General 

Cytology  of  the-Uredinese.     Annals  of  Botany,  xviii:  323-373)  i904- 
Blackman,  H.  V.  and  Eraser,  Miss  H.  C:  Further  Studies  on  the  Sexuality  of 

the  Uredinea;,  with  2  plates.     Annals  of  Botany,  xx:  35-47,  1906. 


RUST   FUNGI  215 

Carleton,.  Mark  A.:  Investigations  of  Rusts.     U.  S.  Dept.  Agr.,  Bureau  of  Plant 

Industry  Bull.  63,  1904. 
Carleton,  Mark  A.:  Lessons  from  the  Grain  Rust  Epidemic  of  1904.     U.  S.  Ucpt. 

Agr.,  Farmers'  Bull.  219,  1905. 
Cheistman,  a.  H.:  Sexual  Reproduction  in  the  Rusts.     Botanical  Gazette,  xx.xix: 

267-274,  1905. 
Christman,  a.  H.:  Observations  on  the  Wintering  of  Grain  Rusts.     Trans.  Wise. 

Acad.  Sci.,  15:  98-107,  1905. 
Coons,  G.  H.:  Some  Investigations  on  the  Cedar  Rust  Fungus,  Gymnosporangium 

juniperi-virginianas.     Ann.  Rep.  Neb.  Exp.  Sta.,  25:  217-245,  pis.  1-5,  191 2. 
DE  Bary,  Anton:  Comparative  Morphology  of  the  Fungi  Mycetozoa  and  Bacteria, 

1887:  274-286. 
DiETEL,  P.:  Uredinales.     Die  natiirlichen  Pflanzenfamihen  I,  Teil  i,  Abteilung**: 

24-81,  1900. 
DuGGAR,  Benjamin  M.:  Fungous  Diseases  of  Plants,  1909:  384-438. 
Eriksson,  Jakob:  Fungoid  Diseases  of  Agricultural  Plants,  191 2:  63-89. 
Eriksson,  Jakob:  On  the  Vegetative  Life  of  Some  Uredineae.     Annals  of  Botany, 

xix:  55. 
Freeman,  E.  M.:  A  Preliminary  List  of  Minnesota  Uredineae.     Minn.  Bot.  Studies, 

2,  part  4:  407,  1901. 
Grove,  W.  B.:  The  British  Rust  Fungi  (Uredinales):  Their  Biology  and  Classifica- 
tion, 1913,  pp.  i-x  +  1-412. 
Heald,  F.  D.:  The  Life  History  of  the  Cedar  Rust  Fungus  Gymnosporangium 
juniperi-virginianas.    Ann.  Rep.  Neb.  Agric.  Exp.  Sta.,  22:  105-113,  pis.  1-13, 
1909. 
Hoffmann,  A.  W.  H.:  Zur  Entwicklungsgeschichte  von  Endophyllum  sempervivi. 

Centralbl.  fur  Bakteriologie,  2,  abt.  32:  137-158,  191 2. 
Hume,    H.   Harold:  Some    Peculiarities    in    Puccinia  Teleutospores.      Botanical 

Gazette,  1899:  418-423. 
Kern,  Frank  D.  :  A  Biologic  and  Taxonomic  Study  of  the  Genus  Gymnosporangium. 

Bull.  N.  Y.  Bot.  Gard.,  7:  391-494,  pis.  151-161,  1909-1911. 
Kern,  Frank  D.:  Gymnosporangium.     North  American  Flora,  7,  part  3:  188-21 1. 
Klebahn,  H.  :  Die  wirtswechselnden  Rostpilze,  1904. 

Kunkel,  Louis   Otto:  Nuclear   Behavior  in   the   Promycelia  of   Caeoma   nitens 
Burrill  and  Puccinia  Peckiana.     Howe  Amer.  Jour.  Bot.,  i:  37-47,  January, 
1914. 
KURSSANOW,  L.:  Zur  Sexualitat  der  Rostpilze.     Zeits.  Bot.,  2:  81-93,  iQio- 
Magnus,  P.:  Weitere  Mittheilung  iiber  die  auf  Farnkrantem  auftretenden  Uredi- 
neen.  Berichten   der  Deutschen  Botanischen  Gesellschaft,  xix.  Heft  10:  578- 
584,  1901. 
Magnus,  P..  Ueber  eine  Function  der  Paraphysen  von  Uredolagern,  nebst  einen 
Beitrage  zur  Kenntniss  der  Gattung  Coleosporium.     Berichten  der  Deutschen 
Botanischen  Gesellschaft,  xx.  Heft  6;  334-339,  1902. 
Massee,  George:  Diseases  of  Cultivated  Plants,  1910:  289-338. 
Massee,  George  and  Ivy:  Mildews,  Rusts  and  Smuts,  1913:  52-182. 
McAlpine,  D.:  The  Rusts  of  Australia.     Dept.  Agric.  Victoria,  1906. 


2l6  MYCOLOGY 

Olive,  Edgar  W.:  Sexual  Cell  Fusions  and  Vegetative  Nuclear  Divisions  in  the 

Rusts.     Annals  of  Botany,  xxii:  331-360,  1908. 
Olive,  Edgar  W.  :  Origin  of  Heteroecism  in  the  Rusts.     Phytopathology,  i:  139- 

149,  October,  191 1. 
Olive,   Edgar   W.:  Intermingling   of   Perennial   Sporophytic   and   Gametophytic 

Generations  in  Puccinia  Podophylli,  P.  obtegens  and  Uromyces  Glycyrrhizas. 

Annales  Mycologici,  ii:  297-311,  August,  1913. 
Pritchard,  F.  J.:  A  Preliminary  Report  on  the  Yearly  Origin  and  Dissemination 

of  Puccinia  graminis.     Botanical  Gazette,  52:  169-192,  1911. 
Reed,  Howard  S.  and  Crabill,  G.  E.:  The  Cedar  Rust  Disease  of  Apples  Caused 

by  Gymnosporangium  juniperi-virginianse.   Tech.  Bull.  9,  Virginia  Agric.  Exper. 

Stat.,  1915. 
Sappin-Trouffy,  P.:  Recherches  histologiques  sur  la  famille  des  Uredinees.     Le 

Botaniste,  5:  59-244,  1896. 
Stewart,    Alban:  An    Anatomical    Study    of    Gymnosporangium    Galls.     Amer. 

Journ.  Bot.,  2:  402-417  with  i  plate,  October,  1915. 
Sydow,  Paul  H.:  Monographia  Uredinearum  seu-specierum  omnium  ad  hunc  usque 

diem  descriptio  et  adumbratio  systematica  auctoribus,  1904. 
Tulasne,  L.  R.:  Second  Memoire  sur  les  Uredinees  et  les  Ustilaginee.     Ann.  Sci. 

Nat.,  iv.  2:  77,  1854. 
von  Tavel,  Dr.  F.:  Vergleichende  Morphologic  der  Pilze,  1892:  123-133. 
VON  TuBEUF,  Dr.  Karl  F.:  Pfianzenkrankheiten,  1895:  340-434. 
Ward,  H.  Marshall:  Illustrations  of  the  Structure  and  Life  History  of  Puccinia 

graminis.     Annals  of  Botany,  ii:  217  with  2  plates. 
Ward,  H.  Marshall:  On  the  Relation  between  Host  and  Parasite  in  the  Bromes 

and  their  Brown  Rust,  Puccinia  dispersa.     Annals  oT  Botany,  xvi:  233,  1902. 
VON  Wettstein,  Dr.  Richard  R.,  Handbuch  der  Systematischen  Botanik,  1911: 
196-202. 

Suborder  Auricularine^. — Family  Auriculariace^. — ^The 
fungi  of  this  family  are  saprophytes,  or  v^^ood-inhabiting  parasites.  The 
basidia  are  borne  directly  on  the  mycelium,  or  in  variously  formed  fruit 
bodies  in  which  the  basidia  form  a  layer.  The  basidia  are  transversely 
divided  into  four  cells.  Auricularia  includes  about  forty  species  of 
which  the  best  known  is,  Auricularia  (Hirneola)  Auricula  Judce,  the  Jew's 
ear  fungus,  which  develops  its  fruit  body  on  rotten  wood.  When  wet,  it 
is  gelatinous;  when  dry,  it  appears  as  a  dry  crust.  It  is  a  rather  gelatin- 
ous, flabby-looking,  thin  expanded  cup  or  saucer-shaped  fungus  of 
a  brownish  color  when  expanded  smooth  inside,  veined  and  plaited  so 
as  to  have  the  resemblance  to  a  human  ear.  It  grows  on  a  variety  of 
trees:  elm,  maple,  hickory,  balsam,  spruce  and  alder  and  up  to  1900, 
it  had  been  collected  in  Ohio,  Maryland,  Indiana,  New  Jersey,  Pennsyl- 
vania and  West  Virginia.     Outside  it  is  velvety  and  grayish-olive. 


GELATINOUS  FUNGI  217 

Auricularia  (Hirneola)  polytricha  is  the  "Mu-esh"  of  the  Chinese,  who 
gather  it  as  an  article  of  food,  in  fact  oak  boughs  are  cut  and  allowed  to 
decay  to  raise  the  fungus. 

Family  Pilacrace^. — ^This  is  a  small  family  of  two  genera,  Pila- 
crclla  and  Pilacre,  with  spheric  stalked  fruit  bodies.  The  basidia  are 
in  capitate  clusters  and  surrounded  at  first  by  a  peridium-Uke  wall, 
which  breaks  at  maturity. 

Suborder  Tremelline^. — Family  Tremellace^. — This  family 
includes  twelve  genera,  of  which  Trcmella  is  the  most  important.  The 
majority  are  widely  distributed  and  live  saprophytically  on  wood,  where 
they  appear  as  soft,  trembhng,  gelatinous  masses,  when  moist,  becoming 
rigid  and  horny  when  dry.  The  basidia  are  longitudinally  divided  by 
two  septa.  The  four  portions  thus  formed  each  bear  a  terminal  basidio- 
spore.  Some  species  of  Tremella  produce  conidiospores.  Tremella 
frondosa  has  been  used  as  food,  but  as  such  is  unsatisfactory.  Tremella 
foliacea  is  of  a  smoky-brown  color,  cold,  clammy  and  trembles  in  the 
hands.  When  stewed,  it  becomes  a  shmy  mess  relished  only  by  the 
Chinese.  Tremella  mesenterica  is  brain-like  in  its  convolutions,  ge- 
latinous in  texture  and  usually  the  size  of  a  walnut,  and  of  an  orange-red 
color. 


CHAPTER  XX 
FLESHY  AND  WOODY  FUNGI 

Suborder  Eubasidii. — The  fungi  of  this  suborder  are  characterized 
by  the  undivided  (unseptate)  basidia,  more  or  less  club-shaped  with 
generally  four,  rarely  six,  eight,  or  two  apical  sterigmata  each  of  which 
bears  a  basidiospoi-e  (Fig.  92).  These  fungi  are  usually  fleshy  and  the 
spores  are  borne  openly  on  wrinkles,  ridges,  gills,  in  pores,  on  spines, 
or  in  closed  fruits,  which  open  regularly,  or  irregularly,  by  splitting. 
Many  of  the  forms  are  edible,  some  are  inedible,  because  of  toughness, 
or  woodiness,  while  others  are  poisonous. 

Cytology. — Recent  studies  by  Juel  (1897),  Maire  (1900),  Ruhland 
(1901),  Harper  (1902),  Levine  (1913)  have  shown  that  as  a  general 
thing  the  hyphal  cells  of  the  mycelium  in  the  HYMENOMYCETES 
and  GASTEROMYCETES  are  binucleate,  and  sometimes,  as  in  Cop- 
rinus  radiatus,  uninucleate.  The  cells  of  the  young  carpophore  are 
binucleate,  but  as  the  fruit  body  matures,  the  majority  of  the  cells  in 
the  stipe  and  pileus  are  multinucleate,  but  this  condition  arises  from 
the  amitotic  fragmentation  of  the  two  nuclei  originally  present  in  each 
cell.  The  subhymenial  cells  from  which  the  basidia  spring  and  the 
paraphyses  are  always  binucleate.  All  the  cells,  which  are  concerned 
directly  with  the  production  of  basidiospores,  are  binucleated  through- 
out their  development.  The  multinucleated  condition  above  noted 
arises  in  cells  of  strictly  limited  development  and  are  found  in  the  organs 
of  nutrition,  support,  transportation,  etc.  Maire  found  that  the  pairs 
of  nuclei  divide  simultaneously,  as  conjugate  nuclei,  so  that  in  the  suc- 
cessive cell  generations  which  arise  in  the  development  of  the  carpo- 
phore the  two  nuclei  in  each  cell  are  of  widely  separated  nuclear  ances- 
try, duplicating  exactly  the  condition  found  in  the  rusts  previously 
described.  The  young  basidium  contains  only  two  nuclei  just  as  in 
the  teliospore  of  the  rust.  These  two  nuclei  fuse  to  form  the  primary 
nucleus  of  the  basidium  which  then  divides  twice  to  furnish  the  nuclei 
for  each  of  the  typically  four  basidiospores.  Levine  (191 3)  who  has 
studied  this  nuclear  division  in  a  number  of  species  of  Boletus,  finds  the 

218 


FLESHY   AND    WOODY   FUNGI  219 

long  axes  of  the  spindles  in  both  divisions  are  commonly  transverse  to 
the  long  axis  of  the  basidium.  The  spores  in  all  of  the  forms  studied 
by  him  are  uninucleate  at  first.  Just  when  the  mycelial  cells  become 
regularly  binucleate  has  not  been  certainly  ascertained  except  in  a  few- 
forms.  Presumably  in  Coprinus  radiatus  the  uninucleate  spores  give 
rise  to  uninucleate  hyphal  cells,  but  Levine  finds  in  his  Boletus  studies 
that  the  primary  spore  nucleus  divides  at  once  to  form  two  nuclei. 
Presumably,  the  nuclear  division  in  other  forms  may  be  delayed,  until 
the  primary  mycelium  has  arisen.  An  alternation  of  generations  com- 
parable to  that  of  the  rusts  is  also  present  in  the  Hymenomycetes  and 
Gasteromycetes.  The  sporophyte  begins  at  some  indefinite  point  in 
the  mycelium  and  extends  through  the  development  of  the  carpophore. 

A.  Hymenomycetes. — The  undivided  basidia  of  these  fungi  bear 
four  basidiospores  perched  on  corresponding  points,  or  sterigmata. 
These  basidia  spring  directly  from  the  mycelium  in  the  primitive  forms, 
but  in  the  more  highly  evolved  types,  the  basidia  are  borne  on  definite 
layers  (hymenial  layers)  together  with  the  paraphyses  and  cystidia 
characteristic  of  some  of  the  forms.  The  hymenia  are  carried  by  special 
fruit  bodies  which  differ  structurally  in  the  different  f amiUes.  These 
fruit  bodies  arise  from  a  profusely  branched  mycelium,  which  radiates 
through  the  organic  substratum,  which  may  consist  of  leaf  mold,  rotten 
wood,  dying  tree  trunks,  and  manurial  waste.  The  hyphal  cells  are 
frequently  united  by  clamp  connections  which  probably  give  greater 
strength  to  them.  Such  are  the  saprophytes.  Some  of  the  hymeno- 
mycetous  fungi  are  parasites  and  five  in  the  bark  and  wood  of  trees, 
and  some  few  are  parasitic  on  the  woody  parts,  leaves,  flowers  and 
developing  fruits  of  certain  shrubs.  Sometimes,  as  in  Armillaria  mellea, 
the  hyphae  become  united  in  strands  with  apical  growth.  These  strands 
are  known  as  rhizomorphs  and  serve  in  part  as  the  resting  organs.  True 
sclerotia  are  also  formed.  The  fruit  bodies  take  various  forms.  The 
most  highly  developed  types  with  stalk,  cap  and  gills  are  known  as 
toadstools.  Some  of  the  simple  forms  are  club-shaped.  Others  have 
spines  and  pores  instead  of  gills  over  which  the  hymenia  are  spread. 

Family  i.  Dacryomycetace^. — The  fruit  body  is  gelatinous,  or 
cartilaginous,  and  of  different  shapes.  The  whole  surface  of  the  fructi- 
fication is  covered  with  a  paHsade-like  layer  of  long  club-shaped  basidia 
which  bear  two-forked  basidia,  each  fork  with  a  basidiospore.  Conidio- 
spore  formation  occurs  in  a  number  of  forms.     The  important  genera 


220 


MYCOLOGY 


are  Dacryomyces,  Guepinia,  Calocera.  Dacryomyces  deliquescens  forms 
gelatinous,  or  gristly,  lumps  on  tree  stumps.  Guepinia  peziza  is  sapro- 
phytic on  oak  stumps.  Calocera  viscosa  is  a  branched  upright  form 
suggesting  the  true  coral  fungi. 

Family  2.  Exobasidiace^. — The  mycelium  of  the  fungi  of  this 
family  Hves  parasitically  in  the  chlorenchyma  of  many  shrubs.  The 
fruit  body  is  a  thin  basidial  layer,  which  breaks  out  of  the  tissues  of  the 
host.  Each  basidium  develops  four  basidio- 
spores;  rarely  5  to  6  are  formed.  Some  of  the 
species  form  galls  on  the  stems,  leaves  and 
flowers  of  ericaceous  shrubs,  such  as  species  of 
Vacciniiim,  Rhododendron,  Azalea,  Andromeda, 
etc.  There  are  two  genera:  Exobasidium  (Fig. 
84),  with  eighteen  species;  and  Microstroma, 
with  two  species.  Exohasidium  caccinii  (Fig. 
84)  develops  swellings  on  the  leaves  of  species 
of  Vacciniiim  of  a  whitish-red  color.  Its 
basidia  are  club-shaped  with  four  sterigma 
and  four  basidiospores.  The  basidiospores  are 
spindle-shaped,  14  to  i6yu  long  by  2  to  3^ 
broad,  colorless  and  smooth.  Exohasidium 
rhododendri  forms  enlargements  of  the  leaves 
of  species  of  Rhododendron  of  greater  or  less 
size;  colored  white,  or  flesh-colored.  Ex- 
Fig.    84.— Floral    gall  ohasidium  ledi  occurs  on   Ledum   in  Finland. 

produced     on     flowers     of 

huckleberry,  Gaylussacia  Exohasidium  andromedcB  grows  on  leaves  and 
resinosa,  by  Exohasidium  ^^j^g  ^f  gpecies  of  Andromeda  in  Europe  and 

vaccina.        Note    enlarged  °    ,  '-  ,.,.  ... 

and  swollen  calyx.    (Pine  America.     Exooasidium    AzalecB  IS  found   on 

mTT^' f  ^i6T"^' ^'  ■^"  ^P^"^^  ^^  ^"^^^^^^  ^^  ^^^^^  America.  E.v- 
obasidium  lauri  forms  widely  spread,  yellow 
then  brownish,  horny,  or  club-like  galls  on  the  stems  of  the  laurel  in 
Italy,  Portugal  and  the  Canary  Islands.  Exohasidium  Warmingii 
attacks  the  living  leaves  of  Saxifraga  aizoon  in  Greenland,  Tyrol  and 
north  Italy. 

Family  3.  Hypochnace^. — The  hymenium  is  cobwebby.  The 
basidia  have  two,  four  or  six  sterigmata.  Cystidia  are  sometimes  present. 
Hypochnus  occurs  on  old  stumps,  on  leaves  and  on  mosses.  Tomen- 
tella  is  another  genus. 


FLESHY   AND    WOODY   FUNGI  221 

Family  4..  Thelephorace.^. — Fruit  bodies  of  a  simple  type  are 
found  in  this  family.  They  form  on  three  trunks,  either  flat 
leathery  crusts  with  the  hymenium  on  the  smooth  upper  surfaces,  or  the 
flat  fructifications  are  raised  above  the  substratum  and  have  bracket- 
like outgrowths,  which  show  an  overlapping  arrangement  with  the 
hymenial  layer  on  the  under  side.  The  important  genera  are  Corticium, 
Stereum  and  Thelephora.  In  Corticium,  the  fructification  is  leathery, 
membranous,  fleshy,  rarely  wholly  gelatinous,  crust-like,  growing  resu- 


FiG.  85. — a  piece  of  old  oak  timber  rotted  by  Slereum  fruslulosum  showing  scat- 
tered frvtiting  bodies.  {After  von  Schrenk,  Hermann,  Bull.  149,  U.  S.  Bureau  of 
Plant  Industry,  1909.) 


pinate.  The  hymenium  is  smooth,  or  pimply,  and  consists  of  club- 
shaped  basidia  with  four  basidiospores.  The  species  are  mostly 
found  on  wood.  C.  vagiim-solani  in  its  sterile  form  is  known  as  Rkiz- 
octonia,  which  apparently  has  been  found  on  sugar  beet,  bean,  carrot, 
cabbage,  potato,  egg  plant  and  a  number  of  other  hosts.  The  hymeno- 
phore  of  this  species  is  white  with  short  basidia  and  elliptic  spores. 
It  frequently  entirely  surrounds  the  green  stems  of  its  host  near  the 
ground.     The    persistent    hymenophore   of    Stereum   is   leathery,   or 


22  2  MYCOLOGY 

woody,  attached  laterally,  or  centrally,  sometimes  as  a  bracket  with  a 
smooth  hymenium.  Stereum  hirsutum  attacks  oak  trees  in  which  the 
wood  becomes  brownish  at  first  and  in  longitudinal  section,  white  or 
yellow  streaks  are  found,  hence  the  common  name  white-piped,  or 
yellow-piped  oak.  In  the  cross-section,  these  streaks  are  white  specks, 
and  another  name,  that  of  "fly  wood,"  is  apropos.  Further  decom- 
position follows.  The  rot  of  woods,  known  as  partridge  wood,  where 
the  timber  becomes  speckled  with  white,  is  due  to  Stereum  frustulosum 


Fig.   86. — Coral-like   fruit-bodies  of  Clavaria  flava.      {Photo  hy  W.  H.  Walmsley.) 


(Fig.  85).  The  fruiting  bodies  are  hard  and  crust-like,  light  brown  to 
grayish  ,  in  color.  The  smothering  fungus  of  seedlings  is  Thelephora 
terrestris  and  T.laciniatum.  Soft  leathery  masses  are  found  at  the  base 
young  trees  of  the  hard  maple.  These  are  numerous,  shelf-like  fruit  of 
bodies,  hemispheric  in  shape  and  in  -mass  may  completely  surround 
and  smother  the  small  tree.  Hymenochcete  noxia  attacks  tropic  plants, 
such  as  cocoa,  tea,  bread  fruit,  camphor  and  the  like. 

Family  5.  Clavariace^. — The  fairy  clubs,  or  coral  funguses  belong 
here.     The  simple,  or  branched,  club-shaped  or  antler-like  hymeno- 


FLESHY   AND    WOODY   FUNGI  323 

phores  are  fleshy,  leathery,  cartilaginous,  or  waxy.  The  basidia  are 
clavate,  interspersed  with  cystidia  and  bear  one  to  four  sterigmata. 

Pistillaria,  Typhula,  Clavaria  and  Sparassis  are  important  genera. 
Many  of  the  species  of  Clavaria  are  edible  (Fig.  86),  but  some  of  them 
are  tough  and  leathery.  The  color  varies,  as  noted  in  the  enumeration 
of  common  American  species  given  below: 

Clavaria flava  (paleyellow)   (Fig.  86). 

Clavaria  aurea  (golden). 

Clavaria  botrytes  (red-tipped). 

Clavaria  cristata  (crested). 

Clavaria  cinerea  (ashen). 

Clavaria  aurantio-cinnabarino  (orange-red) . 

Sparassis  crispa,  a  common  species,  has  its  hymenial  ridges  pro- 
jecting and  much  convolute,  suggesting  a  mammalian  brain.  It  is  too 
tough  to  be  edible. 

Family  6.  Hydnace^. — The  highest  forms  of  this  family  possess 
the  form  of  a  mushroom,  while  others  are  sessile  and  are  resupinate, 
others  without  a  distinct  cap  are  effused.  The  hymenium  is  spread 
over  with  persistent  bristles,  teeth,  tubercles  or  spines.  The  most 
important  genera  are  Phlebia,  Radidum,  Grandinia  Irpex  and  Hydnum 
(Fig.  87).  The  edible  forms  are  included  in  the  last  two  genera. 
The  forms  of  Hydnum  are  extremely  variable.  The  highest  forms, 
such  as  Hydnum  repandum,  have  a  cap  with  a  central  stipe,  while 
in  other  forms  it  is  lateral,  or  absent.  In  some  of  the  lower  forms, 
the  pileus  is  resupinate.  Projecting  spines  are  covered  with  the 
hymenial  surfaces.  A  rot  of  hardwoods  in  America  is  due  to  Hyd- 
num coralloides.  H.  diversidens  with  its  yellowish-white  sporophore 
takes  the  form  of  an  incrustation,^or  bracket  with  downward-projecting 
spines  of  unequal  length.  The  hymenium  renews  itself  by  a  new 
hymenium  growing  through  the  old  one.  It  causes  a  decay  of  timber 
known  as  white  rot.  Hartig  gives  a  careful  description  of  it,  as  it  occurs 
in  Europe.  H.  caput-ursi  is  a  bracket  form  growing  as  excrescences  on 
living  oak  trees  with  its  pendulous  spines  at  first  white,  then  becoming 
yellowish  and  brownish.  H.  caput-medusce.  has  pendulous  tufts  of 
white  to  gray  spines  and  is  found  on  elms  and  oak  trees.  The  spiny 
character  of  H.  erinaceum  (Fig.  87)  suggests  a  hedgehog,  hence  its 
specific  name.  The  last  three  are  fleshy  and  edible.  Irpex  differs 
from  Hydnum  in  having   the  spines  connected  at  the  base,   and  in 


224 


MYCOLOGY 


in  their  being  less  awl-shaped  and  pointed.  /.  obliquus  on  stumps,  /. 
carneus  on  tulip  poplar,  /.  fusco-violaceus  on  pine  trunks  are  American 
species.' 

Family  7.  Polyporace^. — The  fruit  body  of  the  fungi  of  this 
family  are  of  various  substance  and  shape.  The  hymenium  lines  the 
inner  surface  of  pores,  or  grooves,  or  is  spread  over  the  under  surface  of 
the  fruit  body.  The  depressions  are  either  united  vein-like  grooves, 
tubes,    or   honeycombed   cells,    or    twisted   passages.     Concentrically 


■ 

Wt^^^ 

■'^      '^ 

r 

:         f 

,       I 

Fig.   87. — Fruit-body  of    Hydnuni    erinaceum.      {After   Patterson,  Flora   W.,  and 
Charles,  Vera  K.,  Bull.  175,  U.  S.  Dept.  Agric,  pi.  xxxii,  Apr.  29,  1915.) 


formed  lamellae  are  found  rarely.  The  consistency  of  the  fruit  bodies 
of  these  fungi  is  leathery,  fleshy  and  succulent,  while  in  some  the  fruit 
bodies  are  woody  and  perennial.  The  family  is  naturally  divided  into 
four  subfamihes,  as  follows:  Merulioide^,  Polyporoide^,  Fistulin- 
oiDE^,  Boletoide^.  Each  of  these  subfamilies  includes  fungi  which 
are  important  economically. 

MERULOIDE.E. — This  subfamily  includes  two  genera  of  interesting 
fungi:  MeruUus  and  Mycodendron.     Merulius  is  represented  by  sixty- 


PLESHY  AND   WOODY  FUNGI 


225 


three  species  of  which  M.  lacrymans,  the  dry-rot  fungus,  is  most  impor- 
tant. This  fungus  is  of  world-wide  distribution,  where  it  attacks 
structural  wood  work  and  timbers.  It  has  been  so  long  associated  as 
a  destructive  agent  with  the  structural  wood  work  of  men,  that  it  was 
supposed  to  be  an  entirely  domesticated  form  and  not  known  to  exist 
in  the  wild  form.  Recent  investigations  have  shown  that  it  occurs  on 
living  trees,  which  when  used  for  structural  purposes  furnish  wood 
which  is  liable  to  destruction  later  on.  The  mycelium  of  Merulius 
lacrymans  (Fig.   88),  usually  gains  access  to  dressed  boards,  joists,  or 


Fig.  88. — Immature  fruiting  stage  of  dry-rot  fungus  {Merulius  lacrymans)  de- 
veloping on  the  front  of  a  board.  {After  Clinton,  G.  P.,  Rep.  Conn.  Agric.  Exper, 
Slat.,  pi.  xxviii,  1906.) 


rafters  by  the  germination  of  one  of  its  spores  at  a  point  where  the  beam 
may  be  in  contact  with  a  damp  wall.  Its  mycehum  penetrates  the  wood 
and  usually  grows  lengthwise  at  first,  the  water  for  its  extension  being 
supplied  by  larger  more  tube-like  hyphae  known  as  the  conductive  hyphte, 
which  carry  water  to  the  extreme  end  of  the  mycelial  growth.  The  pres- 
ence of  the  fungus  results  in  a  decay  of  the  wood,  which  is  reduced  to  a 
brown  punky  mass,  that  crumbles  between  the  fingers.  When  the  myce- 
lium comes  to  the  surface  of  the  wood,  it  forms  a  white  felt-like  coyering 
studded  with  water  drops,  hence  the  specific  name  lacrymans  referring 
IS 


226 


MYCOLOGY 


to  the  tear-like  drops  of  water  pressed  out  of  the  Hving  hyphal  cells. 
The  mature  sporophore  is  an  amber-brown  color  covered  with  anasto- 
mosing wrinkles  (Fig.  89)  over  the  surface  of  which  the  basidia  bearing 
basidiospores  are  borne.  Two  basidiospores  are  borne  on  pointed 
sterigma  by  each  basidium.  As  the  fungi  by  means  of  its  conducting 
hyphag  is  independent  of  local  water  supplies,  it  can  grow  in  wood,  even 
if  protected  by  an  external  coat  of  paint,  or  varnish,  and  the  builder  is 
chagrined  to  find  such  wood  work  crumble  away  beneath  the  coats  of 
paint.  Mycodendron  is  a  curious  fungus  with  a  fruit  body  which 
suggests  a   muffin  stand,  or  a  pagoda  with  superimposed,  rounded. 


-Fruiting  stage  of   dry-rot  fungus  (Merulius  lacrymans).      {After    Clinton, 
G.  P.,  Rep.  Conn.  Agric.  Exper.  Stat.,  pi.  xxviii,  1906.) 


spore-bearing  shelves  through  which  the  central  stalk  runs  from  one-half 
to  the  next  above.  Mycodendron  paradoxum  has  been  collected  on 
wood  in  Madagascar. 

PoLYPOROiDE^. — This  Subfamily  includes  tough  or  woody  fungi 
found  generally  on  wood  as  bracket-hke  fruit  bodies  of  different 
forms  and  sizes.  The  spore-bearing  surface,  a  hymenium,  consists  of 
furrows,  or  tubes.  In  the  perennial-fruited  forms,  the  tubes  are  often 
found  in  layers.  Mycologists  have  made  a  natural  division  of  the  dif- 
ferent forms  of  fruit  bodies  into  those  which  are  resupinate,  the  annual 
peroi^  species,  the  perennial  peroid  forms  and  those  species  which  are 
like  the  agarics.     The  various  forms  are  of  interest  to  the  scientific  my- 


FLESHY   AND    WOODY   FUNGI  227 

cologist,  but  to  the  mycophagist  they  are  of  use  as  food.  Only  one 
poisonous  form  is  known,  and  that  is  the  medicinal  one,  Fames  laricis, 
but  it  is  so  bitter  and  unattractive,  as  not  to  be  tempting.  Some  of 
them  are  destructive  to  living  trees,  to  timber  used  for  mine  props,  and 
structural  purposes,  and  to  wood  exposed  to  the  weather,  or  in  contact 
with  the  soil. 

The  ease  with  which  the  polypores  are  collected  and  preserved 
makes  them  especially  suitable  for  systematic  study  in  the  classroom. 
Besides,  they  retain  their  characters  when  dried,  so  that  the  keys  used 
for  their  identification  can  be  readily  followed.  Fortunately  also  we 
have  several  manuals  which  cover  the  different  sections  of  our  country. 
They  are  reasonable  enough  in  price  to  be  furnished  for  use  in  the  class- 
room. It  is  suggested  that  boxes  of  the  different  kinds  used  for  this 
purpose  be  filled  with  enough  specimens  to  furnish  each  member  of 
the  class  in  mycology  with  one  specimen  of  each  kind.  There  should 
be  a  sufiicient  number  of  manuals  of  the  region,  where  the  botanic 
institute  is  situated,  to  supply  every  two  members  of  the  class  with 
one,  so  that  the  students  may  use  them  in  groups  of  two.  The 
advertisement  of  the  books  is  here  reproduced  for  the  use  of  teachers 
of  mycology. 

MANUALS  OF  POLYPORES  AND  BOLETES 

By  William  A.  Murrill,  A.  M.,  Ph.  D.,  Assistant  Director  of  the  New  York 
Botanical  Garden,  Editor  of  "Mycologia,"  and  Associate  Editor  of  "North  American 
Flora." 

Northern  Poljrpores,  November,  19 14.  Including  species  found  in  Canada  and 
the  United  States  south  to  Virginia  and  west  to  the  Rockies. 

Southern  Polj^jores,  January,  1915.  Including  species  found  in  the  United 
States  from  North  Carolina  to  Florida  and  west  to  Texas. 

Western  Pol5T)ores,  February,  1915.  Including  species  found  in  the  states  on 
the  Pacific  coast  from  Cahfornia  to  Alaska. 

Tropical  Polypores,  March,  1915.  Including  species  found  in  Mexico,  Central 
America,  southern  Florida,  the  West  Indies,  and  other  islands  between  North 
America  and  South  America. 

American  Boletes,  November,  19 14.  Including  all  the  species  found  in  temperate 
and  tropical  North  America,  both  on  the  mainland  and  on  the  islands,  south  to 
South  America. 

As  satisfactory  keys  of  the  different  genera  and  species  of  the  poly- 
pores and  boletes  are  given  in  these  manuals,  and  as  it  is  presupposed 
that  their  use  will  be  adopted,  keys  of  the  more  common  genera  and 


228 


MYCOLOGY 


species  are  not  given  space  in  this  book.  It  should  be  stated,  however, 
that  Murrill  classifies  his  genera  and  species  differently  from  the  authors 
that  have  preceded  him  where  many  of  the  new  genera  were  classified 
under  the  genera  Polyporus  and  Boletus  (Fig.  90).  The  arrangement 
of  Murrill  seems  to  be  a  more  satisfactory  presentation  of  these  groups 
than  those  systems  which  have  gone  before  and  is  founded  on  more 
natural  characters.  The  nomenclature  which  this  author  adopts  in 
the  several  recommended  manuals  was  f()rcshad(nved  in  \o\.  (>,  i)art  i 


Fig.   90.~7)<j/«7;(s  /,//,  ,i\  in  three  stages  of  devel.  iinnent.      {After  Patterson,  Flora  W.  , 
and  Charles,  Vera  K.,  Bull.  175,  U.  S.  Dept.  Agric,  pi.  x.xxi,  Apr.  29,  1915.) 

(1907),  and  part  2  (1908)  of  the  "North  American  Flora,"  where  keys 
will  also  be  found  with  the  synonymy  which  has  been  omitted  from  the 
manuals.  To  connect  satisfactorily,  the  old  and  the  new  generic  and 
specific  names,  the  treatment  of  the  Polyporace^  in  the  "North 
American  Flora"  should  be  consulted. 

Trametes  roblniophila  is  found  on  decayed  spots  of  living  trunks  of 
Rohinia  pseudacacia  from  Pennsylvania  to  Virginia  and  Missouri,  and 
it  doubtless  causes  decay  of  the  wood.  T.  suaveoleus  is  found  on  willow 
trees,  where  it  causes  serious  decay.     It  has  an  agreeable  odor.     T. 


FLESHY  AND    WOODY   FUNGI 


229 


subiiivosa  is  occasional  on  dead  deciduous  wood  in  Florida,  Louisiana 
and  Mississippi.  At  New  Orleans,  it  was  collected  on  living  water 
oak  and  at  Eustis,  Fla.  on  cypress.  The  species  become  more  abundant 
in  tropic  America  where  nine  have  been  found.  T.  jalapensis  was  col- 
lected on  a  railway  tie  near  Jalapa,  Mexico.  The  species  of  Coriolus 
are  annual.     It  includes  Coriolus  {Polyporns)  versicolor  found  on  all 


Fig.  91. — Piece  of  dead  wood  with'sporoiiii-iK  ,    -    ,     .,..      iomenlaius.      {After  von 
Schrenk,  Hermann,  Bull.  149,  C/.?5.  Bureau  of  Flant  Industry,  pi.  viii,  1909.) 

kinds  of  dead  wood.  It  causes  root  rot  in  many  trees  and  becomes  a 
wood  parasite  of  Catalpa.  It  has  a  leathery,  thin  and  rigid  hymeno- 
phore  depressed  at  the  point  of  attachment.  The  surface  is  velvety 
and  variegated  with  two-colored  zones.  The  pores  are  minute  rounded 
with  ragged  edges,  white  then  yellowish.  Polyporus  arcularius  is  com- 
mon in  the  eastern  United  States  on  dead  branches  and  trunks  of  vari- 


MYCOLOGY 

ous  trees.  P.  caudicimis  is  one  of  the  most  dangerous  enemies  of  shade 
trees  in  Europe  but,  fortunately,  it  is  rare  in  America. 

The  genus  Fames  includes  the  fungi  with  corky,  woody,  or  rarely 
punky  hymenophore,  which  is  sessile,  hoof-shaped,  or  applanate  (Fig. 
91).  The  substance  of  the  fruit  body  is  white,  flesh-colored,  or  wood- 
colored.  The  tubes  are  cylindric  and  usually  thick  walled.  Fomes 
annosus  will  live  on  trunk  and  roots  of  coniferous  trees,  Fomes 
(Pyropolyporus)  igniarius  causes  serious  heart  rots  of  trees.  It  was 
formerly  the  source  of  tinder.  Dcedalea  quercina  (Fig.  202)  is  a  corky, 
or  woody,  species  common  on  oak  and  chestnut  trees.  It  is  at  first 
porous,  but  these  pores  coalesce  to  form  slits  with  blunt  partitions. 
It  is  very  common  about  Philadelphia.  Lenzites  betulinus  is  common 
on  dead  deciduous  wood. 

FiSTULiNOiDEiE, — The  most  important  genus  of  this  subfamily  is 
Fistulina,  which  comprises  about  six  species.  F.  hepatica  is  the  com- 
monest form,  and  is  known  by  its  English  name  beefsteak  fungus  or, 
in  French,  langue  de  hoeiif.  The  tongue-shaped  fruit  body  projects 
from  the  tree  and  is  six  to  ten  inches  across  with  a  liver-colored  and 
sticky  gelatinous  surface.  The  mouths  of  the  tubes  are  closely  packed. 
It  is  edible,  when  fully  mature,  its  flavor  resembhng  beefsteak. 

BoLETOiDE^. — The  members  of  this  subfamily  are  tube-bearing 
fungi  differing  from  the  Polyporoide^  in  their  fleshy  substance  and 
terrestrial  habit.  They  have  a  cap  and  stipe  like  a  mushroom,  but 
porous  tubes  instead  of  gills  on  the  under  cap  surface.  They  occur 
usually  in  forested  tracts  during  summer  and  autumn.  The  annual 
hymenophore  is  usually  centrally  stipitate.  Many  of  the  best  edible 
fungi  (few  of  them  poisonous)  are  found  in  this  subfamily,  which  in- 
cludes, according  to  Murrill  in  North  America,  Central  America  and 
the  West  Indies,  as  far  as  Trinidad,  eleven  genera. 

Boletus  (Tylopilus)  felleus  (Fig.  90)  is  common  iji  woodlands.  It 
is  discarded  as  an  edible  form,  because  of  its  bitter  taste.  Forty-eight 
species  of  Ceriomyces  are  listed  by  Murrill  for  America.  The  genus 
Boletus  proper  is  made  to  contain  only  five  species,  while  Strohilomyces 
strobilaceus  still  retains  its  old  name.  This  rough  shaggy  form  is 
regarded  as  edible. 


CHAPTER  XXI 

MUSHROOMS  AND  TOADSTOOLS 

Family  8.  Agaricace^e. — The  mycelium  of  the  fungi  of  this  fam- 
ily lives  in  the  substratum,  which  may  be  the  soil,  leaf  mould,  rotten 
wood,  old  stumps,  dead  tree  trunks,  or  living  trees,  as  far  as  the  natural 
environment  is  concerned,  and  in  manures,  in  the  decay  of  agricultural 
plants  in  the  fields,  offal,  spent  tan  bark  and  rubbish  heaps,  as  far  as 
man  has  influenced  the  environment.  The  hyphse  may  be  delicate  and 
cobwebby,  thread-hke,  cord-like,  or  in  strands  (rhizomorphs).  They 
are  always  septate,  sometimes  with  clamp  connections  and  their  color 
may  vary  from  white  to  yellow,  or  brown  {Ar miliaria  mellea).  The 
fruit  bodies  are  mostly  fleshy,  rarely  of  membranous,  or  leathery,  con- 
sistency. Usually  of  an  umbelloid  form,  they  may  have  a  sessile  cap, 
or  pileus,  or  the  stalk,  if  present,  may  be  attached  laterally,  although 
it  is  placed  centrally  as  a  general  rule.  The  hymenophore  consists  of 
radiately  arranged  veins,  folds,  or  gills  (lamellae),  which  are  generally 
free  from  each  other,  seldom  anastomosing,  or  dichotomously  branched. 
As  the  popular  name  toadstool  is  suggestive  of  the  commonest  form 
of  these  fleshy  fungi,  a  few  words  of  explanation  with  regard  to  the 
general  structure  will  be  apropos.  Attached  to  the  spreading  myce- 
lium we  find  arising  vertically  the  stalk,  or  stipe.  The  height  of  this 
varies  in  the  different  genera  and  species.  Sometimes  it  is  enlarged 
at  the  base,  at  other  times,  the  stalk  is  perfectly  cylindric.  The  sur- 
face of  the  stipe  may  be  smooth,  rough,  reticulate,  or  stringy,  and  its 
center  may  be  solid,  stuffed,  or  hollow,  as  the  case  may  be.  An  annu- 
lus,  such  as  is  present  in  the  common  mushroom,  may  in  other  forms 
be  absent,  or  well  developed.  Placed  on  the  stem,  or  stipe,  above  we 
find  the  cap,  or  pileus,  which  is  expanded  horizontally.  It  has  a 
domed,  convex  upper  surface  sometimes  with  a  projecting  boss,  or 
umbo;  in  other  forms  it  is  depressed  (crateriform,  umbilicate,  etc.). 
The  gills,  or  lamellae,  are  attached  to  the  lower  surface  of  the  pileus. 
They  may  run  from  the  stipe  to  the  margin,  or  they  may  run  only 
part  way,  so  that  frequently  there  are  secondary  gills  alternating  with 

231 


232 


MYCOLOGY 


the  primary  ones.     The  gills  may  be  free  from  the  stipe,  adnexed,  or 
even  decurrent. 

A  section  of  a  mature  gill  shows  the  following  disposition  of  the 
hyphal  layers.  The  central  part  of  the  gill  consists  of  parallel,  down- 
ward directed  hyphffi,  that  form  the  trama.  Running  out  obliquely 
from  the  trama  are  shorter  cells  which  constitute  the  subhymenium. 
The  basidia,  together  with  their  accompanying  paraphyses  and  cysti- 
dia,  form  a  palisade-like  layer  (the  hymenium)  whose  cells  stand  at 

right  angles  to  the  tramal  hyphae. 
The  basidia  are  furnished  with 
sterigma,  which  bear  the  basidio- 
spores  (Fig.  92).  In  such  forms 
as  the  common  mushroom,  the 
gill  chamber  is  at  first  closed  by 
a  veil  known  as  the  partial  veil, 
or  velum  partiale,  which  ruptures 
when  the  pileus  expands.  The 
part  of  this  membrane  attached 
to  the  stipe  becomes  the  annulus. 
while  the  other  part  remains  at- 
tached in  a  shreddy  condition 
to  the  edge  of  the  cap.  The 
species  of  A  manita  have  a  univer- 
sal veil  which  covers  the  whole 
fruit  body,  and  as  this  enlarges 
the  velum  universale  is  torn  trans- 
FiG.    92.-Coprinus    siercorarius    with  versely,  the  lower  part  forming 

young   and  mature  sporophores  with  gills,    the  death  CUp,  Or  volva,  and  the 
basidia    and    basidiospores    and     cystidia.  ,  ,•  .    . 

{After  Brefeid.)  "PP^r  P^rt  sometimes  remammg 

in  the  form  of  flaky  pieces,  which 
are  distributed  irregularly  over  the  upper  surface  of  the  cap  (Fig.  93). 
A  frill-like  annulus  is  also  found  at  the  top  of  the  stipe  in  the  Amani- 
tas. It  does  not  represent  a  portion  of  the  partial  veil  in  the  Amanitas, 
but  is  a  membrane  which  is  formed  from  a  thick,  loosely  felted 
layer,  which  separates  as  elongation  proceeds  from  the  surface  of  the 
stipe,  retaining  its  connection  with  the  stipe  where  the  stalk  joins  the 
cap.  It  is  pulled  away  from  the  stipe  by  retaining  its  connection  with 
the  edges  of  the  pendant  gills  as  a  continuous  membrane,  which  covers 


MUSHROOMS    AND   TOADSTOOLS  233 

the  gills.  As  the  pileus  expands  the  membrane  becomes  detached  first 
at  the  margin  of  the  cap,  and  it  falls  down  around  the  stipe,  as  a  frill, 
plaited  in  delicate  folds,  corresponding  to  the  former  lines  of  contact 
with  the  lamellae  and  is  now  known  as  the  annulus  superus,  frill,  or 
armilla.  Special  milk  tubes  are  found  in  such  forms  as  species  of  Lac- 
tarius  for  when  these  toadstools  are  wounded  a  milky  fluid  oozes  out  in 
drops.  Each  basidium  usually  bears  four  basidiospores,  sometimes 
thereare  two.     The  color  of  these  spores  is  distinctive,  and  is  used  in 


Fig.  93. — Deadly  amanita  (Amanita  mitscaria)  showing  volva  at  base  of  stem 
and  frill,  like  stem  ring.  {After  Chestnut,  V.  K.,  Bull.  175,  U.  S.  Dept.  Agric,  pi.  i, 
Apr.  29,  1915-)   J 

the  classification  of  the  genera  of  the  family.  We  distinguish  the 
white-spored,  rosy-spored,  ochre-spored  (yellow  or  brown),  brown- 
spored,  black-spored  agarics. 

Buller  in  his  "Researches  on  Fungi"  (1909)  has  carried  on  detailed 
studies  with  numerous  species  of  gill  fungi  and  has  studied  the  physi- 
ology and  mechanics  of  spore  discharge  and  fall.  The  disposal  of  the 
hymenium  beneath  a  pileus  on  gills,  the  rigidity  of  the  fruit  body,  the 
growth  movements  of  the  fruit  body,  all  faciUtate  the  distribution  of  the 
discharged  basidiospores.     The  spores  liberated  from  a  pileus  in  per- 


234  MYCOLOGY 

fectly  still  air  placed  above  a  horizontal  sheet  of  paper  fall  vertically 
downward  and  produce  a  spore  print  of  radiating  lines  of  spores  cor- 
responding to  the  interlamellar  spaces.  The  number  of  spores  liberated 
in  Agaricus  (Psalliota)  campestris  (Fig.  94),  8  cm.  in  diameter,  was 
1,800,000,000  spores.  Coprinus  comatus  formed  5,000,000,000  spores. 
Such  discharge  under  normal  conditions  is  continuous,  but  by  exposing 
the  gills  to  ether,  or  chloroform  vapor,  it  ceases.  BuUer  determined 
that  the  four  spores  on  each  basidium  are  discharged  successively  leav- 
ing the  sterigmata  a  few  seconds  or  minutes  of  one  another,  so  that  an 
entire  mushroom  will  discharge  in  total  about  a  million  spores  a  minute 


Fig.  94. —  Meadow  mushroom,  Agaricus  campestris.  A,  View  of  under  surface; 
a,  annulus;  g,  gills;  B,  side  view;  s,  stipe;  p,  pileus  or  cap.  {From  Gager,  after  W.  A. 
Murrill.) 

for  two  or  more  days.  The  rate  of  fall  of  hymenomycetous  spores  ranges 
from  0.3  to  6.0  mm.  per  second;  those  of  the  mushroom  shortly  after 
they  have  left  the  gills  fall  at  a  speed  approximately  i  mm.  per  second. 
The  path  described  by  a  spore  in  its  fall  has  been  called  a  sporabola. 
Buller  has  divided  the  fruit  bodies  of  the  Agaricace^  into  two  types, 
the  Coprinus  comatus  type  and  the  Agaricus  campestris  type.  The 
deliquescence  in  the  first  type  is  an  autodigestion,  which  renders  impor- 
tant mechanic  assistance  in  the  process  of  spore  discharge,  where  the 
process  proceeds  in  succession  from  below  upward,  so  that  autodiges- 
tion refnoves  those  parts  of  the  gills  from  which  the  spores  have  been 


MUSHROOMS    AND    TOADSTOOLS  235 

discharged,  and  permits  the  spores  to  fall  more  easily  past  the  neighbor- 
ing gill  surfaces. 

Development  of  the  Fruit  Bodies.— Kikmson^  has  studied  the  develop- 
ment of  the  mushroom  {Agaricus  {PsaUiota)  campestris)  (Fig.  94). — 
The  youngest  stage  is  the  homogeneous  primordium  01  the  carpophore 
composed  of  slender,  uniform,  dense  hyphae,  intricately  interwoven,  and 
surrounded  by  a  thin  layer  of  hyphse  of  a  looser  arrangement.  This 
layer  is  the  universal  veil  which  grows  until  the  form  of  the  fruit 
appears  when  it  is  torn  into  white  floccose  patches  on  the  pileus.  In 
the  very  young  primordium  then  there  is  no  evidence  of  a  differentiation 
into  stem  and  pileus  and  at  this  stage  stained  longitudinal  sections  show 
two  small  deeply  stained  internal  areas  near  the  upper  end  of  the  young 
fruit  body  and  some  distance  from  the  surface.  The  hyphae  here  are 
richer  in  protoplasm  and  form  an  annular  area  within  the  fruit  body. 
This  area  now  increases  in  extent  and  many  hyphae  grow  from  its 
upper  portion  downward  to  form  the  primordial  layer  of  the  hymenium. 
These  downward  growing  hyphge  are  slender  and  terete  and  taper 
pointed,  which  enables  them  to  push  between  the  surrounding  hyphse. 
Soon  after  these  hymenial  hyphse  grow  downward  there  is  a  cessation  of 
growth.  Just  below  this  area  which  results  in  the  rupture  and  separa- 
tion of  the  hyphse  at  this  point  in  a  corresponding  internal  annular  area, 
forming  the  well-known  "gill  cavity"  which  at  first  is  very  minute. 

With  the  formation  of  this  annular  primordium  of  the  hymenium 
the  primordia  of  the  stem,  veil  and  pileus  are  differentiated.  The 
period  of  elongation  of  the  parts  after  they  have  been  organized  follows 
in  succession.  The  marginal  veil  completes  its  period  of  elongation 
first,  then  the  stem,  followed  by  the  pileus,  and  finally,  the  hymenium 
where  in  examples  studied  Atkinson  secured  two-spored  basidia. 

A  somewhat  similar  development  takes  place  in  Agaricus  Rodmani, 
a  form  which  grows  in  grassy  ground  and  paved  gutters  in  cities  from 
May  to  July.  The  sequence  of  events  in  the  growth  of  the  fruit  body  is 
given  by  Atkinson. ^  He  finds  that  the  primordium  of  the  fruit  body 
is  oval  in  form  and  homogeneous  in  structure,  consisting  of  intricately 
woven  hyphse.     The  hymenophore  primordium  arises  as  an  internal 

^Atkinson,  George  F.:  The  Development  of  Agaricus  campestris.  Botanical 
Gazette,  42:  215-221,  September,  1906. 

2  Atkinson,  George  F.:  Morphology  and  Development  of  Agaricus  Rodmani. 
Proceedings  American  Philosophical  Society,  191 5:  309-343,  with  7  plates. 


236  MYCOLOGY 

annular  zone  of  new  growth  toward  the  upper  part  of  the  young  fruit 
body  (basidiocarp)  and  with  its  origin  the  four  primary  parts  of  the 
basidiocarp,  pileus,  stem,  marginal  veil  and  hymenophore  are  differen- 
tiated. By  the  continued  growth  and  multiplication  of  hyphae  rich  in 
protoplasm,  which  are  parallel  and  directed  downward,  the  hymeno- 
phore primordium  becomes  more  compact  to  form  a  level  palisade 
zone,  and  as  the  ground  tissue  beneath  lags  behind  in  growth,  the  more 
rapid  growth  of  hymenophore  causes  a  rupture  of  the  ground  tissue 
beneath  and  an  annular  gill  cavity  arises.  The  lamellae  project  into  this 
cavity,  as  downward-growing  radial  sahents  of  the  level  palisade  zone, 
beginning  next  to  the  stem  and  proceeding  in  a  centrifugal  direction. 

Cultivation  of  the  Mushroom. — The  commercial  growing  of  mush- 
rooms has  been  placed  upon  a  sure  financial  basis  within  recent  years 
and  around  Philadelphia,  notably  in  Chester  County,  there  are  large 
concerns  which  make  the  culture  of  mushrooms  a  specialty.  Mush- 
room cultivation  is  an  important  business  in  Europe,  especially  in 
France  where  certain  of  the  grades  are  canned  and  bottled  for  export 
trade.  Mushrooms  are  grown  in  America  in  long  mushroom  houses, 
or  sheds  especially  constructed  and  heated  for  the  purposes  of  the  trade. 
Cellars  are  also  devoted  to  the  industry.  Sometimes  they  are  grown 
under  the  benches  of  greenhouses  devoted  to  the  raising  of  other  plants. 
The  beds  are  so  constructed  of  boards  that  they  rise  in  tiers  of  four,  or 
five  with  a  central  aisle,  or  in  the  larger  houses  there  are  tiers  of  beds 
along  the  walls  and  in  the  center  of  the  house  with  two  aisles  running 
lengthwise  with  a  cross  aisle  at  the  far  end  or  in  the  middle  of  the  house. 

Stable  manure  is  used  as  the  compost  for  commercial  mushroom 
culture.  Bedding  straw  should  also  be  included  with  the  manure  in 
the  compost.  The  manure  should  be  the  best  that  can  be  obtained. 
It  should  be  thrown  into  piles  about  four  feet  high  and  forked  over 
occasionally  to  assist  the  fermentation  process,  which  is  assisted  further 
by  wetting  the  fermenting  mass  occasionally  until  the  fermentation  is 
completed,  which  is  usually  at  the  end  of  three  weeks.  During  this 
time  all  objectionable  odor  should  be  lost  and  the  temperature  should 
decline  to  120°  or  i30°F.  Out  of  this  compost  the  beds  are  constructed 
by  compressing  the  mass  with  blows  of  a  spade,  or  by  a  compressing 
board.  Growers  cover  the  manure  bed  with  a  thin  layer  of  garden  soil 
one  to  one  and  a  half  inches  deep.  This  operation  is  known  as  casing, 
and  is  performed  after  the  spawning  operation  has  been  completed. 


MUSHROOMS   AND   TOADSTOOLS  237 

Spawning  consists  in  breaking  up  the  bricks  of  spawn  into  about  ten 
pieces  and  one  piece  of  spawn,  which  consists  of  hard  manure  pene- 
trated by  the  mushroom  hyphae,  is  used  for  each  square  foot  of  bed 
space.  The  piece  of  spawn  should  be  covered  by  about  one  inch  of 
compost  which  should  have  a  temperature  of  70°  to  75°F.  The  casing 
soil  should  be  well  moistened  by  repeated  sprinkhng,  and  not  by  a  sud- 
den drenching.  Under  favorable  conditions,  such  a  bed  should  come 
into  bearing  in  from  six  to  eight  weeks  after  spawning,  and  during  the 
period  of  production  constant  care  in  the  matter  of  watering  is  neces- 
sary to  keep  the  beds  up  to  the  maximum  conditions  of  production. 
The  making  of  spawn  is  an  art  in  itself  and  the  process  is  fully  described 
in  a  recent  book  by  B.  M.  Duggar  on  "Mushroom  Growing,"  published 
in  191 5  by  Orange  Judd  Company,  New  York.  Duggar  also  ascer- 
tained in  his  studies  of  the  mushroom  that  fragments  of  growing  mush- 
rooms obtained  under  aseptic  conditions  could  be  made  the  starting 
point  for  pure  cultures  of  spawn.  This  is  based  on  the  fact,  that  a 
small  piece  of  the  inner  stipe  tissue  of  a  fresh  mushroom  will,  when 
placed  on  any  suitable  sterile  nutrient  medium,  promptly  develop  a 
mycelium.  The  method  of  making  pure  cultures  is  described  in  Bulle- 
tin 85,  Bureau  of  Plant  Industry,  United  States  Department  of  Agri- 
culture and  in  Duggar's  "Mushroom  Growing"  and  need  not  be  re- 
peated here. 

Chemistry  and  Toxicology  of  Mushrooms. — With  the  increase 
in  the  cost  of  hving  and  in  our  population,  which  is  beginning  to  feel  the 
shortage  of  food  supplies,  earnest  attention  has  been  directed  to  foods, 
such  as  the  edible  wild  fungi,  which  are  frequently  abundant  during  the 
summer  months.  One  phase  of  this  study  has  been  the  investigation 
of  the  food  value  of  mushrooms  and  toadstools.  Chemical  analyses 
have  been  made  to  ascertain  what  they  contain.  It  has  been  found, 
that  such  a  fungus  as  Polyporus  sulphureus,  has  over  70  per  cent,  of 
water,  while  species  of  Agariciis  and  Coprinus  have  fully  90  per  cent, 
of  water.  As  to  nitrogen,  although  the  proportion  of  this  element  in 
the  dry  matter  of  different  fleshy  species  varies  from  2  to  6  per  cent.,  it 
has  been  found  that  much  of  the  nitrogen  is  present  in  the  form  of  non- 
protein substance  of  a  very  low  food  value  and  some  of  it  enters  into 
the  composition  of  a  substance  closely  related  to  cellulose.  Thus,  not- 
withstanding the  fact  that  Coprinus  comatns  contains  5.79  per  cent,  of 
nitrogen,  we  find  only  0.82  per  cent,  as  available  (digestible)  proteins, 


238 


MYCOLOGY 


SO  that  the  food  value  of  this  form  is  less  than  had  formerly  been  sup- 
posed. The  fatty  substances  soluble  in  ether  are  present  to  the  amount 
of  4  to  8  per  cent.  The  carbohydrates  (cellulose,  glycogen,  trehalose, 
mannite,  glucose,  etc.)  make  up  the  largest  part  of  the  dry  matter  of 
the  mushroom.  Starch  usually  present  in  higher  plants  is  absent  in 
these  fungi.     The  ash  varies  greatly,  varying  from  i,o8  to  15  per  cent. 

with  potassium  as  the  most 
abundant  element.  Sulphuric 
acid  occurs  in  the  ash  of  all  fungi, 
with  1.58  per  cent,  in  the  ash  of 
Hehella  esculenta. 

The  poisonous  substances  are 
alkaloids,  such  as  choline,  found 
in  Amanita  muscaria,  Hehella 
esculenta  and  other  fungi,  neurin 
(deadly),  muscarin,  the  most 
dangerous  alkaloid  found  in  toad- 
stools, as  in  Amanita  muscaria 
(Fig.  93).  Phallin,  a  deadly 
poison,  found  in  Amanita  phal- 
loides,  is  albuminous  in  nature. 
Helvellic  acid,  a  deadly  poisonous 
substance,  occurs  in  Helvetia  es- 
culenta, especially  in  old  decaying 
specimens.  The  symptoms  of 
poisoning  with  muscarin  are  long 
delayed.  They  may  be  summed 
up  in  the  words  of  Mr.  V.  K. 
Chestnut  (Circular  No.  13  Divi- 
sion of  Botany,  United  States 
Department  of  Agriculture) : 
"Vomiting  and  diarrhoea  almost 
always  occur,  with  a  pronounced  flow  of  saliva,  suppression  of  the 
urine,  and  various  cerebral  phenomena  beginning  with  giddiness, 
loss  of  confidence  in  one's  ability  to  make  ordinary  movements,  and 
derangements  of  vision.  This  is  succeeded  by  stupor,  cold  sweats, 
and  a  very  marked  weakening  of  the  heart's  action.  In  case  of  rapid 
recovery,  the  stupor  is  short  and  usually  marked  with  mild  delirium. 


Fig.  95. — Deadly  amanita,  Amanita 
phalloides,  showing  death  cup,  or  volva,  at 
base  of  stipe.  {From  Gager,  after  E.  M. 
Kiltredge.) 


MUSHROOMS    AND    TOADSTOOLS  239 

In  fatal  cases,  the  stupor  continues  from  one  to  two  or  three  days, 
and  death  at  last  ensues  from  the  gradual  weakening  and  final  stop- 
page of  the  heart's  action."  Fortunately  an  antidote  has  been  found 
in  the  hypodermic  injection  of  atropine  in  doses  of  one-hundredth  to 
one-sixtieth  of  a  grain.  Strong  emetics  should  also  be  used  to  rid  the 
stomach  of  the  offending  food.  The  action  of  phallin  from  Amanita 
phalloides  (Fig.  95)  for  which  no  antidote  is  known  except  the  adminis- 
tration of  emetics  and  the  transfusion  of  blood  into  the  patient,  which 
may  be  of  little  avail  is  best  summed  up  in  Chestnut's  account:  "The 
fundamental  injury  is  not  due,  as  in  the  case  of  muscarin,  to  a  paralysis 
of  the  nerves  controlling  the  action  of  the  heart,  but  to  a  direct  effect 
on  the  blood  corpuscles.  These  are  quickly  dissolved  by  phallin,  the 
blood  serum  escaping  from  the  blood-vessels  into  the  alimentary  canal, 
and  the  whole  system  being  drained  rapidly  of  its  vitality.  No  bad 
taste  warns  the  victim,  nor  do  the  preUminary  symptoms  begin  until 
nine  to  fourteen  hours  after  the  poisonous  mushrooms  are  eaten.  There 
is  then  considerable  abdominal  pain  and  there  may  be  cramps  in  the 
legs  and  other  nervous  phenomena,  such  as  convulsions  and  even  lock- 
jaw, or  other  kinds  of  tetanic  spasms.  The  pulse  is  weak,  the  abdom- 
inal pain  is  followed  rapidly  by  nausea,  vomiting,  and  extreme  diarrhoea, 
the  intestinal  discharges  assuming  the  rice-water  condition  characteristic 
of  cholera.  The  latter  symptoms  are  maintained  persistently,  generally 
without  loss  of  consciousness,  until  death  ensues,  which  happens  in 
from  two  to  four  days." 

B.  Gasteromycetes. — -The  fungi  known  as  the  Gasteromycetes 
{yaarrip  =  belly,  sac  -f  /jlvktjs  =  fungus)  have  the  basidial  layers,  or 
hymenium,  enclosed  within  a  peridium,  as  in  the  common  puff-ball. 
The  shell  or  hull  enclosing  the  masses  of  spores  is  called  the  peridium, 
which  is  a  simple  uniform  layer  in  some  genera  (Scleroderma),  or  it  con- 
sists of  two  distinct  layers,  the  exoperidium  and  the  endoperidium. 
The  earth-star  (Geaster)  has  a  thick  outer  peridium,  which  splits  in  a 
stellate  manner,  later  becoming  reflexed.  The  exoperidium  in  such 
genera  as  Bovista  and  Lycoperdon  is  a  loose  pliable  coat  often  having 
spines  and  warts.  Many  of  the  genera  are  stalkless,  but  other  genera, 
such  as  Tylostoma,  are  stalked.  Inside  of  an  unripe  puff-ball,  we  find  a 
white  fleshy  mass  of  soft  cellular  matter,  the  gleba.  As  the  fruit 
bodies  grow  they  become  chambered.  The  chambers,  in  countless 
numbers,  are  narrow,  irregularly  curved  and  branched,  separated  from 


240  MYCOLOGY 

each  other  by  curved  plates  of  tissue  which  anastomose  in  every  direc- 
tion. The  walls  of  the  chambers  consist  of  layers  of  branched  hyphse 
bearing  the  basidia  which  line  the  interior  walls  of  the  cavities  and  con- 
stitute the  hymenium.  Each  basidium  usually  bears  four  spores. 
The  way  the  spores  are  borne  on  the  basidia  is  characteristic.  They  are 
almost  sessile  in  Geaster,  in  Bovista  they  are  found  on  long  sterigmata. 
Mitremyces  may  have  as  many  as  a  dozen  basidiospores,  which  are 
sessile  and  lateral. 

When  the  puff-ball  reaches  full  size  and  ripens,  the  tissues  become 
moist,  deliquesce  and  change  in  color.  The  tissues  are  absorbed  and 
disappear  and  the  whole  mass  dries  up,  leaving  the  interior  sur- 
rounded by  the  peridium  filled  with  a  dry  dusty  mass  usually  con- 
sisting of  slender  threads  (the  capillitium)  and  countless  multi- 
tudes of  ripe  spores.  The  threads  of  the  capillitium  are  absent  in  many 
genera,  but  when  present  they  are  characteristic  and  used  as  important 
points  in  the  classification.  There  are  two  distinct  kinds  of  capillitial 
threads.  In  one  kind,  the  threads  are  long  hair-like  strands,  simple, 
more  or  less  branched  and  interwoven,  proceeding  from  the  inner  walls 
of  the  peridium,  or  from  the  centrally  placed  columella.  The  second 
type,  characteristic  of  Bovista,  Bovlstella  and  Mycenastrum,  has  rela- 
tively short  and  branched  threads  entirely  separate  and  distinct  from 
each  other  and  are  not  connected  with  the  peridium  nor  the  columella. 
The  bird-nest  fungi  are  characterized  by  the  thickening  of  the  walls  of 
the  glebal  chambers  to  form  separate  little  seed-hke  bodies  enclosing  the 
spores.  These  are  known  as  peridioles.  The  ripe  spores  in  some  are 
smooth,  some  are  spinulose,  while  in  shape  they  are  globose,  oblong  or 
oval. 

The  most  primitive  forms  of  these  fungi  are  probably  the  subter- 
ranean forms  included  in  the  family  Hymenogastrace^.  In  one 
classification  of  the  Gasteromycetes,  the  division  of  the  famihes  is 
based  on  whether  the  sporophore  is  borne  above  or  below  the  ground. 
The  family  Hymenogastrace^  with  subterranean  fruit  bodies  belongs 
to  one  division,  all  of  the  other  families  to  the  other  division. 

Family  i.  Hymenogastrace^. — The  subterranean  fruit  bodies  of 
these  fungi  suggest  those  of  the  families  Terfeziace^  and  Tuberace^ 
among  the  ASCOMYCETALES,  but  the  spores  of  the  two  latter 
families  are  borne  in  asci,  and  are  known  as  ascospores,  while  those  of 
the  former  family  are  borne  on  basidia  and  are  known  as  basidiospores. 


MUSHROOMS   AND   TOADSTOOLS  24 1 

Most  of  the  forms  are  irregularly  globose  and  grow  under  trees,  some- 
times their  association  with  certain  kinds  of  trees  suggesting  a  para- 
sitic attachment.  They  are  often  found  in  sandy  places,  where  they 
are  exposed  frequently  by  rain  erosion.  The  mycelium  of  these  fungi 
is  filamentous,  or  cord-like.  The  gleba  is  richly  chambered  and  the 
walls  of  the  glebal  chambers  are  lined  with  the  hymenium.  Cystidia 
are  often  found  between  the  basidia.  The  fruit  bodies  are  variously 
shaped.  In  Lycogalopsis,  they  are  hemispheric;  in  Phyllogaster,  pear- 
shaped;  in  Cauloglossum,  club-shaped;  some  are  stalked  and  suggest 
the  shape  of  the  Agaricace^. 

Very  few  of  the  forms  are  known  commonly,  and  of  the  dozen  Cali- 
fornian  species,  many  are  known  imperfectly  by  a  single  collection. 
Gaiitieria  and  Sclerogaster  have  each  a  single  species  in  California; 
Hymenogaster  and  Octaviana  are  represented  by  two  Californian  species, 
while  Hysterangium  and  Melanogaster  have  three  species  in  California. 
Two  species  of  Rhizopogon  and  one  of  Melanogaster  are  found  in  South 
Carolina.  The  climate  probably  has  something  to  do  with  this 
distribution. 

Family  2.  Tylostomace^.  At  first,  the  fruit  body  is  subter- 
ranean, later  as  in  Tylostoma  niammosa,  a  form  found  in  heathland,  it  is 
raised  on  a  stalk  not  prolonged  as  an  axis.  The  peridium  is  double,  the 
outer  one  falUng  off  at  maturity,  the  inner  one  is  thin.  The  uncham- 
bered  gleba  possesses  well-developed  capilUtial  threads,  which  are  con- 
nected with  the  inner  wall  of  the  endoperidium.  The  basidia  in 
Tylostoma  are  unicellular,  club-shaped  and  bear  four  laterally  placed 
spores,  one  above  the  other  on  well-developed  sterigmata,  thus  differ- 
ing from  the  other  two  basidiomycetous  fungi. 

Family  3.  Lycoperdace^. — -The  fruit  body  from  the  beginning  is 
epigaeic.  Its  gleba  is  chambered  richly  and  the  inner  walls  of  each 
chamber  are  lined  with  a  hymenium.  The  peridium  is  differentiated 
into  an  outer  and  an  inner  peridium.  The  gleba,  when  ripe,  breaks 
down  into  powdery  spores  and  richly  branched  capilHtial  threads.  This 
family  contains  some  of  our  most  delicious  and  important  food  species, 
if  they  are  taken  before  fully  mature.  The  genus  Ly  coper  don,  in  which 
the  true  peridium  opens  by  an  apical  mouth,  includes  over  one  hundred 
species,  which  in  America  can  be  divided  into  the  purple-spored  series, 
and  the  olive-spored  series.  Lycoperdon  atropurpureum  is  found  in  sandy 
pastures,  woods  and  bushy  places  commonly  in  the  months  from  August 
16 


242 


MYCOLOGY 


to  October.  It  is  an  extremely  variable  species,  Lycoperdon  gemma- 
turn,  an  olive-spored  species,  has  a  turbinate  shape,  its  outer  peridium 
being  marked  with  long,  thick,  erect  spines,  or  warts  of  irregular  shape 
with  intervening  smaller  ones,  whitish,  or  gray  in  color.  The  larger 
spines  fall  away  first  imparting  to  the  surface  of  the  peridium  a  reticu- 
late appearance.  It  often  grows  cespitosely  on  the  ground,  or  rotten 
tree  trunks  in  woodlands.  Lycoperdon  pyriforme  is  another  common 
species  found  in  woods  and  clearings  on  the  ground,  or  on  decaying 
wood.     It  is  edible,  tender  and  of  second-class  flavor  when  young. 


Fig.  96. — Fruit-body  of  Calvatia  cyalhiformis.      {Photo,  by  IF.  H.  Wahnsley.) 


The  largest  puff-balls  are  included  in  the  genus  Calvatia  (Fig.  96), 
which  differs  from  Lycoperdon  in  the  absence  of  an  apical  mouth  and 
a  regular  dehiscence.  The  fruit  bodies  are  globose,  or  top-shaped,  aris- 
ing on  the  surface  of  the  ground  from  subterranean,  cord-like  hyphae. 
Calvatia  cyathiformis  (Fig.  96)  which  is  edible,  if  eaten  when  white  in- 
side, grows  in  open  grassy  fields  and  lawns  and  reaches  a  diameter  of 
three  to  six  inches.  Calvatia  gigantea,  the  giant  puff-ball,  grows  in 
pastures  and  meadows.  Usually  the  fruit  bodies  are  ten  to  twenty 
inches  in  diameter  and  even  larger.     The  genus  Bovista  has  a  fragile 


MUSHROOMS   AND   TOADSTOOLS  243 

exoperidium,  and  in  the  absence  of  a  sterile  base  and  the  fact  that  the 
fruit  body  separates  easily  from  the  place  of  attachment  it  is  distin- 
guished from  Lycoperdon.     Because   they  are  readily  detached  and 


Fig.  97. — Specimen  of  Geaster  fornicatus  from  Carleton  Rea,  England.      {After  Lloyd, 
J.  U.,  and  C.  G.,  Bull.  5,  Lloyd  Library,  June,  1902,  Mycological  Series  No.  2.) 

readily  blown  about,  they  are  called  "tumblers."  Catastoma  has  an 
outer  peridium  which  splits  by  a  circular  Hne  of  cleavage,  so  that  the 
upper  part  is  dislodged  carrying  along  with  it  the  inner  peridium  which 


244  MYCOLOGY 

opens  by  a  mouth  that  is  situated  at  the  actual  base  of  the  plant  as  it 
grows.  The  lower  part  remains  as  a  saucer-shaped  body  in  the  soil. 
A  capillitium  is  present.  Catastoma  circumscissum  is  the  common  species. 

The  earth  stars  are  included  in  the  genus  Geaster,  where  the  peridium 
consists  of  three  persistent  coats,  the  two  outer  adhere  and  split  into 
leathery,  stellate  divisions  exposing  the  parchment-like  inner  peridium, 
which  opens  by  an  apical  pore  (Fig.  97).  It  has  a  columella.  The  spores 
are  dark  brown  and  mixed  with  the  simple  capillitial  threads.  Geaster 
hygrometricus  is  the  common  species.  It  grows  in  sandy  soil  and  in  dry 
weather  its  segments  are  strongly  recurved,  but  in  wet  weather  they 
expand,  hence  the  plant  is  sometimes  dubbed  poor  man's  weather 
glass.  Astr(Eus,  which  resembles  Geaster,  is  distinguished  by  the 
absence  of  a  columella  and  by  the  long  capilUtial  threads  which  are 
much  branched  and  interwoven. 

Family  4.  Nidulariace^. — The  following  account  of  the  family 
of  bird's-nest  fungi  is  taken  from  Bulletin  175,  United  States  Depart- 
ment of  Agriculture,  on  "Mushrooms  and  Other  Common  Fungi"  by 
Flora  W.  Patterson  and  Vera  K.  Charles.  Dried  material  of  these 
fungi  might  be  kept  for  use  by  the  class  in  the  systematic  study  of  the 
higher  fungi  with  the  following  key  at  hand.  The  types  should  be 
used  as  unknowns. 

Members  of  the  family  Nidulariace^  are  represented  by  small, 
leathery,  cup-shaped  plants  growing  on  old  sacking,  manure,  earth,  and 
decaying  or  dried  wood.  The  common  name  is  suggested  by  the  form 
of  the  peridium,  which  is  cup-shaped  and  contains  many  small,  lenticu- 
lar bodies  (peridiola)  resembhng  eggs.  The  mouth  of  the  peridium  is  at 
first  covered  by  a  membrane  (epiphragm),  which  later  becomes  ruptured 
and  exposes  the  peridioles.  In  Cyathiis  and  Crucibulum,  the  peridi- 
oles  are  attached  to  the  inner  wall  of  the  peridium  by  elastic  cords 
called  funiculi.  The  spore-bearing  tissue  and  spores  are  never  resolved 
into  a  dusty  mass,  as  in  many  Gasteromycetes,  but  persist  in  the 
form  of  peridiola  which  contain  the  spores,  which  are  hyaline  and 
ellipsoidal  to  subglobose. 

Key  to  Nidulariace^ 

Peridium  with  several  to  many  sporangioles: 
Peridium  torn  at  the  apex  in  opening— 

Sporangioles  not  attached  to  the  inner  wall  of  the  peridium.   Nidiilaria. 


MUSHROOMS    AND    TOADSTOOLS  245 

Peridium  opening  by  a  deciduous  membrane — 

Sporangioles  attached  to  the  inner  wall  of  the  peridium — 
Peridium  of  three  united  layers  and  spores  mixed  with 

filaments Cyalhua. 

Peridium  of  a  single  layer  and  spores  not  mixed  with 

filaments Crudbnlmn. 


Cyathus 

In  Cyalhiis  the  peridium  is  cup-like  and  composed  of  three  layers. 
The  apex  is  covered  by  a  white  membrane,  which  bursts,  disclosing  egg- 
like bodies,  the  peridiola,  which  usually  fill  about  one-half  of  the  cup. 
The  peridiola  are  attached  to  the  inner  wall  of  the  peridium  by  an  elastic 
cord,  which  is  attached  to  each  peridiolum  in  a  depression  on  one  side. 

Cyathus  stercoreus 

Peridium  cylindrical,  campanulate  to  infundibuliform,  sessile  or  with  an  elon- 
gated base,  light  brownish,  at  first  with  shaggy,  matted  hairs  which  disappear  in  age, 
interior  smooth  and  nonstriate;  peridiola  black. 

Cyathus  skrcoreus  is  an  exceedingly  common  species  and  is  to  be  found  growing 
on  manure  or  in  heavily  manured  places.  It  is  subject  to  considerable  variation  in 
size  and  form. 

Cyathus  striatus 

Peridium  obconic,  exterior  even,  brownish,  hairy,  interior  striate,  lead-colored; 
apex  truncate,  covered  by  a  white  membrane,  which  is  at  first  strigose;  peridiola 
compressed,  subcircular. 

Plant  one-half  to  three-fourths  inch  in  height  and  about  three-eighths  inch  in 
diameter. 

Cyathus  vernicosus 

Peridium  bell-shaped,  subsessile,  base  narrow,  broadly  open  above,  exterior  at 
first  brownish,  silky  tomentose,  becoming  smooth,  interior  dull  lead  color,  smooth. 
Differs  from  Cyathus  striatus  in  the  even,  non-fluted  inner  surface  of  the  peridium  and 
in  the  larger  peridiola. 

Plant  about  one-half  inch  in  height  and  about  three-eighths  inch  in  diameter. 


Crucibulum 

In  Crucibulum  the  peridium  is  cup-shaped  and  consists  of  one  thick 
fibrous  layer,  Hned  by  a  very  thin,  smooth,  and  shining  layer.     The 


246  MYCOLOGY 

mouth  when  young  is  covered  with  a  yellowish  tomentose  membrane, 
the  peridiola  are  more  numerous  than  in  the  preceding  genus,  and  each  is 
Attached  to  the  peridium  by  an  elastic  cord  which  springs  from  a  pro- 
jection on  the  peridiolum.  The  plants  are  smaller  than  in  the  genus 
Cyathus. 

Crucibulum  vidgare 

Peridium  yellowish-brown,  becoming  paler  with  age,  outer  surface  when  young 
velvety  tomentose,  inner  surface  smooth  and  shining;  mouth  at  first  closed  by  a  yel- 
lowish membrane,  which  ruptures  and  exposes  the  peridiola.  Peridiola  biconcave, 
with  a  projection  on  one  side  from  which  originates  the  elastic  cord  which  attaches 
the  peridiola  to  the  peridium. 

Plant  about  one-fourth  inch  in  height  and  about  the  same  in  diameter. 

Family  5.  Sclerodermace^. — The  fruit  bodies  of  the  fungi  in- 
cluded in  this  family  are  subterranean,  or  epigeic,  globose,  sessile,  or 
occasionally  with  a  root-like  stalk.  The  peridium  is  generally  simple, 
thick,  rough,  warty,  or  scaly,  opening  irregularly  at  maturity.  The 
gleba  consists  of  rounded  basidia-bearing  parts,  which  are  separated  by 
sterile  veins  or  strands  of  hyphge.  The  individual  basidia  are  pear- 
shaped  to  club-shaped  with  spores  which  are  often  lateral  in  position. 
The  capilhtiiim  is  rudimentary.  Scleroderma  is  the  most  common  genus 
with  sessile  fruit  bodies  and  thick,  hard,  leathery  peridium,  frequently 
warty.  It  usually  bursts  at  the  apex  into  stellate  lobes.  Scleroderma 
geaster  grows  in  sandy  woods,  banks  or  along  roadsides.  S.  vidgare 
is  common  in  dry  situations,  or  hard  ground,  along  cinder  paths  and 
gravel  walks. 

Family  6.  Sph^robolace^. — The  fruit  body  is  on  the  surface  of 
the  ground.  The  periphery  of  the  gleba  is  furnished  with  a  palisade- 
like layer  of  radially  arranged  turgescent  cells.  The  basidia-bearing 
portion  of  the  gleba  is  penetrated  by  sterile  veins,  or  hyphal  strands. 
When  ripe  the  gelatinous  gleba  is  forcibly  ejected  from  the  fruit  body  by 
the  inversion  of  the  pahsade-like  layer.  The  family  includes  a  single 
genus,  Sphcerobolus,  of  five  species.  The  best-known  species  is  S.  car- 
pobolus  of  cosmopolitan  distribution. 

C.  Phallomycetes. — The  carrion  fungi,  stink-horn  fungi,  or  dead- 
men's  fingers,  resembles  the  button  stage  of  the  Amanitas,  and  the  puff- 
balls  when  still  young,  but  later  the  outer  wall  is  ruptured  and  the  stem 
elongates  carrying  upward  the  sporogenous  tissue  as  a  terminal  cap,  or 
enlargement.     The  subterranean  mycehum  is  cord-hke  and  from  it  the 


MUSHROOMS    AND    TOADSTOOLS 


247 


fruit  body  arises  which  has  a  pcridium  of  two  or  three  layers.  The 
outer  peridium  is  leathery  and  tough,  while  the  inner  peridium  is  gelat- 
inous at  maturity.  The  outer  peridium  remains  at  the  base,  as  a 
cup  called  the  volva.  The  sporophore,  pileus,  or  cap,  is  raised  up  on  the 
end  of  a  stalk,  or  stipe,  which  is  usually  spongy  in  character.  The 
sporophore  takes  a  variety  of  forms,  but  in  all  cases,  its  outer  surface  at 


y^'"- 


Fig.   98. 


-Clathrus  cancellatus,  fully  mature   fruit-body,  natural   size.      {After   Ed. 
Fischer,  Die  naliirlichen  Pflanzenfamilien  I.  lA**,  p.  282.) 


first  represents  the  hymenium  which  deliquesces  at  maturity,  so  that  the 
minute  spores  are  imbedded  in  a  greenish,  fetid  sUme,  which  gives  off  a 
penetrating,  nauseating  odor,  attractive  to  blue-bottle  flies,  that  lick 
off  the  malodorous  slime  with  evident  enjoyment  and  are  the  agents 
by  which  the  spores  are  distributed.  In  fact,  it  has  been  proved  that 
the  basidiospores  germinate  better  after  passage  through  the  alimentary 


248  MYCOLOGY 

canals  of  flies.  The  gleba  is  the  fruiting  portion  of  the  phalloid  and  its . 
bulk  appears  considerable  in  the  early  egg-shaped  stage  of  the  fruit 
body.  As  the  carrion  fungus  matures,  it  forms  proportionately  less  of 
the  fruit  body,  for  it  is  converted  into  the  greenish,  mucilaginous  mass 
which  is  removed  by  the  flies.  Some  forms  like  Didyophora  have  a  veil 
that  hangs  under  the  pileus  and  spreads  out  as  a  net  around  the  stem. 
Although  it  is  called  the  veil,  it  is  more  correctly  the  indusium.  The 
sporophore  in  genera  like  Clathrus  (Fig.  98)  takes  the  form  of  a  hollow 
sphere,  or  of  a  basket-like  lattice,  while  in  other  genera  it  resembles  the 
open  iron  framework  of  a  lantern,  a  brazier,  a  crinoid,  or  storie-lily,  an 
octopus,  or  even  a  sea-anemone.  One  tropic  form  of  Brazil  has  been 
called  Pilzblumen  by  the  Germans.  The  species  are  not  common  in 
temperate  regions,  but  in  the  tropics  they  are  richer  in  forms  and  more 
abundant;  for  example,  in  Florida  the  species  of  Clathrus  are  common, 
the  writer  finding  four  specimens  within  a  quarter  of  a  mile  along  a  road 
across  the  sand  dunes  at  Ormond. 

Development  of  the  Carrion  Fungi. — Several  authors  have  studied 
the  development  of  several  forms  of  the  Phallomycetes,  notably 
Burt  and  Atkinson.  Burt^  has  contributed  three  papers  dealing  with 
the  genera  Anthurus,  Clathrus  and  Mutinus,  while  Atkinson's  studies^ 
are  concerned  with  Ithyphallus  and  Didyophora. 

Burt  finds  in  the  Clathrace^  that  the  egg  consists  of  cortical  and 
medullary  systems  continued  upward  from  the  mycelial  strand  in  the 
earliest  stage.  The  cortical  layer  gives  rise  to  the  outer  layer  of  the 
volva,  the  cortical  plates  and  the  pseudoparenchyma  of  the  receptacu- 
lum.  The  medullary  portion  gives  rise  to  the  gelatinous  masses  of  the 
gelatinous  layer  of  the  volva,  to  the  gleba,  and  to  the  gelatinous  tissue 
of  the  chambers  of  the  receptaculum.  The  elongation  of  the  receptacle 
in  Clathrus  columnatus  (Fig.  98)  begins  at  the  base  and  after  its  elonga- 
tion the  gleba  hangs  suspended  from  the  arch  of  the  receptaculum  by 
medullary  tissue  constituting  the  chamber  masses  of  the  receptacle. 

In  the  earliest  recognizable  stage  of  Mutinus  caninus,  the  egg  con- 
sists of  the  cortical  and  medullary  tissues  of   the  mycelial  strand, 

1  Burt,  Edward  A.:  A  North  American  Anthurus:  Its  Structure  and  Develop- 
ment. Memoirs  Boston  Soc.  of  Nat.  Hist.,  3:  487  (1894);  The  Development  of 
Mutinus  caninus.  Annals  of  Botany,  10:  343  (1896);  The  Phalloideas  of  the  United 
States.     Development  of  the  Receptacle  of  Clathrus  columnaLus. 

Atkinson,  George  F.:  The  Origin  and  Taxonomic  Value  of  the  Veil  in  Dicty- 
ophora  and  Ithyphallus.     Botanical  Gazette,  50:  1-20,  January,  1911. 


MUSHROOMS   AND   TOADSTOOLS 


249 


continued  directly  upward  from  the  strand.  Of  these  tissues,  the 
medullary  bundle  spreads  out  at  its  upper  end  and  forms  a  dense 
sheaf-like  head  by  repeated  branching  and  anastomosing.  The 
cortical  layer  of  tissue  becomes  the  outer  wall  of  the  volva;  the  sheaf- 
like head  gradually  differentiates  into  all  the  other  parts  of  the  older 
egg.  In  such  differentiation  the  central 
column  first  appears.  The  formation  of 
the  gelatinous  layer  of  the  volva  now  begins 
in  the  periphery  of  the  head.  A  dense 
dome-shaped  mass  arises.  Along  the  inner 
surface  of  the  dense  zone  and  next  to  the  in- 
termediate tissue,  the  rudiment  of  the  gleba 
arises  from  the  clustered  swollen  ends  of 
lateral  branches  of  the  tramal  tissue.  These 
hyphal  ends  take  position  in  a  palisade 
layer  facing  the  intermediate  tissues  and  by 
the  crowding  in  of  new  hyphal  ends  (basidia) 
the  surface  of  this  layer  becomes  greatly 
enlarged  and  thrown  into  folds  and  torn 
from  the  intermediate  tissue.  The  rudiment 
of  the  stipe  arises  in  the  intermediate  tissue 
lying  next  to  the  central  column  by  the  forma- 
tion of  deeply  staining  tissue  rich  in  proto- 
plasm. Somewhat  later,  masses  of  tissue  in 
the  dense  and  intricately  interwoven  rudi- 
ment of  the  stipe  show  a  tendency  toward 
gelatinization.  These  masses  mark  the 
position  of  the  later  chamber-cavities  in  the 
wall.  Toward  the  upper  end  of  the  stipe, 
such  masses  are  in  contact  with  the  central 
column,  and  they  mark  the  position  of  the 
pits  which  open  into  the  main  central  cavity 
of  the  stipe  in  mature  stages  of  M.  can  in  us. 

The  chamber  walls  are  thrown  into  folds  through  a  more  rapid  growth 
of  the  pseudoparenchyma  than  that  of  other  parts  of  the  egg.  Final 
elongation  of  the  stipe  and  elevation  of  the  gleba  is  brought  about 
through  the  straightening  out  of  the  folds  in  the  chamber  walls. 

The  studies  of  Atkinson  deal  with  the  origin  of  the  veil  of  Dictyo- 


FiG.  99. —  Mature  stink- 
horn,  Diclyophora  duplicata. 
{Photo  by   W.  II.    Walmsley.) 


2  50 


MYCOLOGY 


phoni  (Figs,  gg  and   loo),  and   llhyphaUiis.     From  such  studies,  he 
confirms  the  making  of  two  genera  out  of  them.     His  plates  show 


Fig.  100. — Diclyophora  phallaidea.     Fully  developed  fruit-body  with  veil  2/3  natural 
size.      {After  Alf  Moller  in  Die  natUrlichen  pflanzenfamilien  I.  lA  **,  p.  294.) 

that  three  common  forms  were  examined,  viz.,  Ilhy phallus  impudicus, 
Diclyophora  duplicata  and  the  Phallus  Ravenellii. 

Two   families    are    distinguished:    Clathrace^    and  Phallace^ 
which  may  be  distinguished  as  follows: 


MUSHROOMS    AND    TOADSTOOLS 


251 


Receptacle  latticed  or  irregularly  branched,  sessile  or  stalked; 
gleba  inclosed  within  the  receptacle.     Family  i.  Clathrace^. 

Receptacle  tubular  or  cyhndric,  capitate,  with  the  gleba  external. 
Family  2.  Piiallace.e. 


Fig.  ioi. — A,  B,  Dictyophora  phalloidea.  A,  Longitudinal  section  of  a  fruit-body 
fully  stretched  beyond  volva  (natural  size);  B,  longitudinal  section  of  a  young  fruit- 
body  (twice  enlarged);  G,  volva  mucilage;  a,  gleba;  H,  cap;  /,  indusium;  Sw,  stipe; 
Pi,  primordial  layer  between  cap  and  indusium';  Pi,  primordial  layer  between  in- 
dusium and  stipe;  S,  S,  tissue  of  stem;  B,  tissue  of  base  of  fruit-body.  {After  Ed. 
Fischer  in  Die  naliirlichen  PJlanzejifamilien  I.  lA**,  p.  295.) 

The  first  family,  according  to  "Die  natiirlichen  Pflanzenfamilien, " 
comprises  eleven  genera  of  which  Clathrtis  (Fig.  98),  Sinihlum,  An- 
thurus  are  North  American.  Three  species  of  Clathrus  have  been  col- 
lected in  this  country.     Simhlum  rubescens  was  collected  originally  on 


252  MYCOLOGY 

Long  Island  and  later  in  Nebraska,  while  Anthurus  horcalis  has  been 
found  in  New  York,  Massachusetts  and  Pennsylvania. 

The  family  Phallace^  is  represented  in  the  eastern  United  States 
by  three  important  and  interesting  genera,  viz.,  Mutinus,  I  thy  phallus, 
Didyophora  (Figs.  99,  100,  loi).  Mutinus  is  the  simplest  form  with 
the  gleba  Ijorne  on  the  upper  portion  of  the  stipe  without  the  hanging 
cap.  Mutinus  caninus  has  a  hollow,  perforate  stipe  reddish  in  color 
bearing  the  greenish  bad-smelling  spore  slime  over  its  upper  end. 
Ithyphallus  impudicus,  our  commonest  species,  has  a  globose  volva, 
cylindric,  hollow  spongy  stalk  bearing  a  campanulate  pileus,  the  spore- 
bearing  surface  being  reticulate  pitted.  Didyophora  duplicata,  which 
resembles  the  Brazihan  Pilzblumen,  D.  phalloidea  in  (Figs.  100,  loi) 
the  possession  of  a  long  white  indusium,  which  hangs  down  beneath  the 
cap  like  a  spread-out  hoopskirt.  The  terminal  cap  is  campanulate 
and  after  the  removal  of  the  malodorous  greenish  spore  slime  appears 
reticulate-pitted.     The  volva  is  prominent. 

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Underwood,  L.  M.  and  Earle,  T.  S.  :  The  Distribution  of  the  Species  of  Gymno- 

sporangium    in    the   South  on  Juniperus  virginiana]  Botanical    Gazette,    22: 

255-258,  1896. 
Underwood,  Lucien  M.:  Moulds,   Mildews  and  Mushrooms.     A   Guide  to  the 

Systematic  Study  of  the  Fungi  and  Mycetozoa  and  Their  Literature,   New 

York,  1899. 
Verrill,  a.  E.:  A  Recent  Case  of  Mushroom  Intoxication.     Science,  new  ser.,  xl: 

408-410,  Sept.  18,  19 14. 
von  Tavel,  Dr.  F.:  Vergleichenae  Morphologic  der  Pilze,  1892:  140-185. 
Wemyss,  Fulton  T.:  The   Dispersion  of  Spores  by  the  Agency  of  Insects,  with 

Special  Reference  to  the  Phalloidea;.     Annals  of  Botany,  iii:  207.      ^ 
White,  Edward  A.:  A  Preliminary  Report  on  the  Hymeniales  of  Connecticut. 

Bull.  3,  State  Geological  and  Natural  History  Survey,  1905. 


MUSHROOMS   AND   TOADSTOOLS  257 

White,  Edward  A.:  Second  Report  on  the  Hymeniales  of  Connecticut.     Bull. 

15,  State  Geological  and  Natural  History  Survey,  1910,  pp.  70,  pis.  28. 
White,   V.   S.:  The  Tylostomaceaj    of  North  America.     Bull.   Torr._Bot."Club, 

28:  421-444,  August,  1901. 
Yates,  Harry  S.:  The  Comparative  Histology  of  Certain  California   Boletaceae. 

University  of  California  Publications  in  Botany,  6:  221-274,  pls.  21-25,  Feb. 

25,  1916. 


CHAPTER  XXII 
FUNGI  IMPERFECTI  (DEUTEROMYCETES) 

The  life  histories  of  the  fungi  belonging  to  this  group  are  imperfectly 
known,  and  hence,  it  happens  that  when  it  has  been  established,  the 
type  is  removed  from  the  fungi  imperfecti  and  properly  classified  with 
some  other  group.  The  name  Deuteromycetes,  also  applied  to  the 
imperfect  fungi,  is  derived  from  the  Greek,  devrepos  =  second.  Many 
important  parasites  are  included  here,  and  hence,  it  has  been  considered 
important  by  mycologists  to  give  the  characters  by  which  the  fungi 
imperfecti  are  distinguished. 

General  Characters. — The  mycelium  consists  of  septate,  hyaline,  or 
pigmented  hyphas,  or  only  of  chain  of  yeast-like  cells.  The  hyphas  are 
diffuse,  or  plectenchymatous  (irXeKTos  =  woven).  Stromata  are  fre- 
quently present.  The  fructification  is  a  single  conidiophore,  a  layer 
of  conidiophores,  or  a  conidial  fructification  (pycnidium).  The 
Fungi  Imperfecti  represent  the  accessory  fruit  forms  of  the  ASCOMY- 
CETALES,  rarely  those  of  other  orders.  The  mycelium  is  practically 
the  same  as  found  in  the  sac  fungi.  The  septate  hyphae  spread  over 
the  substratum,  or  penetrate  its  interior,  and  the  fungi  live  sapro- 
phytically,  or  parasitically.  The  arrangement  of  the  hyphas  in  various 
ways  has  suggested  the  segregation  of  species  and  genera.  The  under 
layer  (subiculum  =  felted  stratum  of  hyphae)  is  of  loose,  entangled 
threads,  or  disc-like  bodies,  or  radially  stretching  fibrils,  aggregated 
loosely.  The  stroma  on  the  contrary  represents  compact  tissue,  cor- 
responding to  similarly  named  structures  in  the  ASCOMYCETALES. 
The  fruit  layer  originates  in  or  on  the  stroma. 

Reproduction  is  dependent  on  exogenously  produced  spores,  known 
as  conidiospores.  In  the  simplest  cases,  the  mycelium  gives  rise  at 
indefinite  places  to  outgrowths,  which  are  separated  as  spores.  There 
arise  from  the  mycelium,  erect  conidiophores  which  form  conidiospores 
in  the  different  species.  With  an  unbranched  conidiophore,  the  conidio- 
spores arise  at  its  apex  followed  by  a  second,  a  third,  etc.  When  the 
end  of  the  conidiophore  is  globutar,  the  spores  arise  on  the  ends  of 
sterigma.     By  the  branching  of  the  conidiophores  originate  conidial 

258 


rUNGI  IMPERFECTI    (dEUTEROMYCETES)  259 


Fig.  102. — Phylloslicta  pavice  on  horse-chestnut  leaves.      (Cold  Spring  Harbor,  L.I., 
July  28.  1915-) 


26o  MYCOLOGY 

strands,  which  suggest  the  inflorescences  of  flowering  plants.  One  can 
separate  these  into  monopodial,  or  sympodial  forms.  A  bundle  of  coni- 
diophores  is  known  as  a  coremium  {Kopr^na  =  broom).  If  the  conidio- 
phores  are  arranged  side  by  side,  they  form  a  conidial  layer,  which 
arises  on  the  upper  surface  of  a  stroma.  Such  a  conidial  layer  may  be 
folded,  or  it  may  be  chambered,  the  irregular  chambered  spaces  being 
lined  with  the  conidial  layer.  Finally,  the  conidial  layer  may  be  in- 
closed in  receptacles  called  pycnidium,  which  correspond  to  those  of 
the  Pyrenomycetiine^.  The  conidiospores  are  of  different  sizes, 
hence  one  can  distinguish  them  as  a  micropycnidia  and  as  macro- 
pycnidia,  and  the  spores  as  micro-  and  macropycnospores.  Stylospores 
are  those  spores  borne  on  a  filament  {oTxiKos  =  a  column).  This  term 
is  also  superfluous.  The  number  of  fungi  imperfecti  surpasses  the 
ASCOMYCETALES. 

Systematic  Position. — Fuckel  includes  all  those  fungous  forms 
as  fungi  imperfecti  which  have  no  final  fruit  forms,  such  as  asci 
and  basidia.  The  name  Deuteromycetes  of  Saccardo  is  less  fortunate 
than  that  of  Fuckel.  That  many  fungi  imperfecti  represent  accessory 
fruit  forms  of  ASCOMYCETALES  is  known,  so  that  the  group  is  not 
a  permanent  systematic  entity.  It  is  a  motley  assemblage  of  hetero- 
geneous forms.  As  with  the  large  group,  so  it  is  with  the  genera. 
Some  of  the  genera  inclose  not  always  related  forms,  that  is  of  the  same 
phylogenetic  series.  Schroeter  calls  such  genera  Formgattungen  (  = 
form  genera).  In  the  following  classification  of  them,  this  point  of 
view  must  be  kept  prominently  in  view,  for  a  natural  classification  of 
Fungi  Imperfecti  is  in  the  nature  of  things  an  impossibility.  The  great- 
est number  are  saprophytes,  useful  in  the  destruction  of  dead  plant 
parts.  Many  are  parasites  and  produce  dangerous  diseases  in  culti- 
vated plants. 

A.  Conidia  in  pycnidia,  or  chamber-like  hollows.     I.   SPH^ROPSI- 
DALES. 

B.  Conidia    in    conidial    layer    formed    ultimately    wholly    free.     II. 
MELANCONIALES. 

C.  Conidia  on  conidiophores.     Single  or  in   coremia.     III.  HYPHO- 
MYCETALES. 

I.  SPH^ROPSIDALES.— The  conidia  are  formed  in  pycnidia. 
The  receptacles  are  closed  or  open  by  a  pore,  or  by  a  slit  suggesting 


FUNGI   IMPERrECTI    (dEUTEROMYCETES^ 


?6l 


groups  of  ASCOMYCETALES.  Four  families  are  included  in  this 
order,  and  these  families  include  a  considerable  number  of  important 
genera  of  fungi,  which  specifically  are  the  cause  of  important  plant 
diseases.  PhyUosticta  is  a  genus,  the  species  of  which  are  confined  to 
leaves,  and  they  produce  characteristic  leaf  spots  on  a  great  variety  of 
plants.  The  specific  name  of  the  fungus  is  usually  derived  from  that 
of  the  host  plant  attacked,  as  for  example,  PhyUosticta  catalpce,  which 


Fig.  103. — Six  j3en  Davis  apples  showing  apple  blotch  (Phyllostica  solilaria). 
{After  Scott,  W.  M.,  and  Rorer,  J.  B.,  Bull.  144,  U.  S.  Bureau  of  Plant Jndustry, 
March  6,  1909.) 


grows  on  the  leaves  of  the  catalpa.  The  group  has  been  monographed 
systematically  by  J.  B.  Ellis.  The  spores  are  small,  egg-shaped  or 
elongated,  unseptate  and  in  color  pale  green,  or  hyaline,  produced  in 
pycnidia.  The  most  important  species  of  this  genus  are  PhyUosticta 
ampelopsidis  on  the  Virginia  creeper  {A  mpelopsis) ;  catalpcB  on  catalpa 
leaves;  labruscce  on  the  leaves  of  the  grape;  pavi<^  on  horse  chest- 
nut leaves  (Fig.  102);  PhyUosticta  solitaria  E.  and  E.  (Figs.  103  and 
104)  is  the  cause  of  apple  blotch,  and  violce  on  violets.     The  conidio- 


262 


MYCOLOGY 


spores  in  Phoma  are  colorless  and  unicellular.  The  pycnidia  are 
black  with  a  terminal  pore  and  depressed  in  the  tissues  of  the  host. 
The  genus  is  arbitrarily  limited  to  those  species  in  which  the  spores 
are  less  than  15^,  for  the  larger  spored  forms  have  been  placed  in  the 
genus  Macrophoma.  The  most  important  species  from  the  pathologic 
viewpoint  are  out  of  the  iioo  species  recognized  the  following:  Phoma 
betcB  is  the  cause  of  the  heart  rot  and  blight  of  beets.  Phoma  batata 
produces  a  dry  rot  of  sweet  potato;  while  Phoma  solani  behaves  much 


nrn  o  0 


Fig.  104. — Microscopic  characters  of  apple  blotch  fungus  {Phyllosticta  solilaria). 
I, vertical  section  of  pycnidium  showing  pycnospores;  2,  3,  4,  5,  mature  pycnospores; 
6,  7,  8,  germinating  spores;  9,  mycelium.  {After  Scott,  W  M..  and  Rorer,  J.  B.,  Bull. 
144,  U.  S.  Bureau  of  Plant  Industry,  pi.  Hi,  March  16,  1909.) 


like  the  damping-o£f  fungus,  attacking  seedling  egg  plants  near  the  sur- 
face of  the  ground.  The  most  destructive  fungus  of  the  genus  Sphcerop- 
sis  is  S.  malorum  which  causes  the  decay  of  apples,  quinces  and  pears 
and  attacks  the  stem  of  the  apple  tree  producing  characteristic  cankers. 
The  genus  includes  about  180  species.  The  150  species  of  the  genus 
C oniothyrium  are  widely  spread  geographically.  The  blight  of  rasp- 
berry canes  is  due  to  Coniothyrium  Fuckelii,  which  has  only  recently 
come  into  prominence  in  the  United  States.     The  genus  Septoria  in- 


FUNGI  IMPERFECTI  (dEUTEROMYCETES) 


263 


Fig.  105. — Septoria  leaf  spot  disease  of  celery,  or  celery  blight.      (After  Coons,  G.  N., 
and  Levin,  Ezra,  Spec.  Bull.  77,  Mich.  Agric.  Coll.  Exper.  Stat.,  March.  1916. 


SPORES^ 


Fig.  106. — Section  through  leaf  spot  of  celery  blight  (Septoria)  ^i  i-lis) 

in  leaf  tissue  and  pycnidium  with  exuding  pycnospores.      (After  Coons,  G.  11.,  and 
Levin,  Ezra,  Spec.  Bull.  77,  Mich.  Agric.  Coll.  Exper.  Slat.,  March,  1916.) 


264  MYCOLOGY 

eludes  the  fungi  which  c§iuse  the  leaf  spot  of  the  pear,  Septoria  pyricola, 
the  late  blight  of  the  celery  S.  petroselini  (Figs.  105  and  106),  the  leaf 
blight  of  the  tomato  S.  lycopersici  and  the  leaf  spot  of  currants,  S.  rihis. 
The  pycnidia  in  this  genus  develop  under  the  epidermis  of  the  host 
producing  leaf  spots.  The  center  of  the  leaf  spot  is  occupied  by  the  pore 
of  the  spheric,  black  pycnidium.  Leptothyrium  pomi  is  an  imperfect 
fungus  responsible  for  the  sooty  blotch  of  the  apple  and  other 
plants.  According  to  Floyd  the  same  fungus  causes  the  fly  speck  of 
apples.  The  genus  Entomosporium  is  a  small  one  with  closed  half- 
spheric,  black  pycnidia.  The  spores  suggest  an  insect  in  being  four- 
celled,  the  cells  being  arranged  cross-like  with  attenuated  extremities 
and  swollen  bases.  Entomosporium  maculatum  is  the  cause  of  the  leaf 
blight  of  the  pear  and  quince. 

II.  MELANCONIALES.^ — The  mycelium  is  formed  in  the  interior 
of  the  host  plants.  The  fruit  is  in  the  form  of  a  conidial  hymenium, 
which  is  produced  below  the  epidermis  of  the  host,  breaking  through 
clefts  in  the  surface  of  the  host  as  bright  or  black  spots.  The  conidio- 
phores  stand  closely  together  and  are  simple,  or  rarely  branched,  hya- 
line, or  rarely  dark-colored.  Pycnidia  are  unknown  in  this  group  of 
imperfect  fungi.  The  spores  are  of  different  shapes,  single  or  in  chains. 
The  order  includes  both  parasites  and  saprophytes.  The  pustule,  or 
acervulus,  which  produces  spores  in  Gleosporium  may  be  extensive 
The  short  conidiophore  arise  from  or  are  inclosed  within  a  cushion, 
or  stroma,  of  fungous  tissue.  The  rupture  of  the  epidermis  of  the  host 
is  accomplished  by  the  opening  of  the  stroma.  The  ovoidal,  fusiform, 
slightly  curved  hyahne  spores  are  discharged  with  the  opening  of  the 
stroma.  Some  species  of  Gloeosporium  are  connected  with  other  genera, 
viz.,  Glomerella  (rufomaculans) ,  Gnomonia  and  Pseud opeziza  the  im- 
perfect stages  of  which  were  placed  as  species  under  the  form  genus 
Glososporium,  which  is  the  important  form  pathologically  speaking. 
As  examples  of  the  form  genus  Gloeosporium,  we  have  G.  ampelophagum 
which  causes  the  anthracnose  of  the  grape;  G.  venetum  which  is  re- 
sponsible for  the  anthracnose  of  blackberry  and  raspberry,  while  other 
species  attack   the   linden,  walnut,  pine   and   Norway  maple. 

In  Colletotrichum  (Fig.  107)  the  conidial  cushions  have  a  bristly 
border,  while  the  conidiospores  are  in  chains.  Colletotrichum  Lindemuth- 
ianum  causes  anthracnose  of  bean,  an  important  disease  in  gardens  and 
fields  (Fig.  107).    The  cotton  is  attacked  by  C.  gossypii,  citrus  fruits  by 


FUNGI  IMPERFECTI  (dEUTEROMYCETEs) 


!65 


4   M 


\  i 


^k 


Fig.   107. — Anthracnose  cankers  on  bean  pods   (Colletolrichum  Lindemidhianum) 
(After  Whetzel,  H.  H.,  Bull.  255,  Cornell  Agric.  Exper.  Stat.) 


266 


MYCOLOGY 


C.  glceosporioides,  clovers  and  alfalfa  by  C.  trijolii  and  the  snapdragon 
by  C.  antirrhini.  Usually  the  diseases  on  these  plants  induced  by  species 
of  Colletotrichum  are  known  as  anthracnose  (Fig.  107).  Coryneum  Bei- 
jerinckii  is  a  destructive  fungus  causing  the  peach  blight.  Pestalozzia 
Guepini  var.  vaccinii  is  a  fungus  often  found  upon  the  cranberry  leaves 
and  fruits.  The  conidiospores  are  three-celled,  the  terminal  cells  with 
filiform  appendages.  The  shot-hole  disease  of  plum  and  cherry  is  due  to 
Cylindrosporium  padi.  The  formation  of  the  acervuli  is  followed  by  the 
falling  out  of  the  disease  areas  of  the  leaf  resulting  in  the  formation 

of  the  characteristic  shot-hole. 
The  fruit  spot  of  apples  is  caused 
by  C.  pomii. 

III.  HYPHOMYCETALES. 
— The  hyphae  are  septate, 
branched  in  or  on  the  substra- 
tum. They  are  dark,  or  hyaline, 
separate,  or  bound  into  coremia, 
or  layer-like  cushions.  The  con- 
idiospores may  exist  as  oidio- 
spores  through  the  separation  of 
the  hypha.  The  conidiophores 
are  simple,  or  branched.  The 
conidiospores  of  different  shapes 
and  colors  are  borne  in  a  variety 
of  ways  on  the  conidiophores  or 
their  branches.  The  genera  may 
be  arranged  in  three  series. 

A.  MyceHum  and  spores  light- 
colored:  Oospora,  Monilia, 
Oidium,  Sporotrichum,  Botrytis,  Cephalothecium,  Ramularia,  Cercos- 
porella,  Piricularia.  B .  Mycelium  dark-colored  at  least  with  age ;  spores 
generally  dark:  Fusicladium,  Polythrincium,  Scoletotrichum,  Clado- 
sporium,  Helminthosporium,  Macrosporium,  Alternaria,  Cercospora, 
C.  Conidiophores  in  the  form  of  a  tuberculate  mass,  or  sporodochium : 
Volutella,  Fusarmm.  As  examples  of  common  disease  producing  forms 
of  the  above  genera  without  enumerating  all  of  the  more  important 
species  may  be  mentioned  the  potato  scab  fungus,  Actinomyces  chro- 
mogenes,  the  early  blight  of  potato  fungus,  Macrosporiums  olani;  the 


Fig.,  108. — Sweet-potato  stem  rot 
{Fusarium  balatalis).  Section  through 
sweet  potato  showing  blackened  ring  just 
below  surface  caused  by  the  stem-rot  fun- 
gus. {After  Harter,  L.  L.,  U.  S.  Farmers' 
Bull.  714,  March  ii,  1916.) 


FUNGI    IMPERrECTI    (dEUTEROMYCETES) 


267 


fungus  which  causes  leaf  spot  of  beets,  Cercospora  beticola.  The  form 
genus  Fusarium  (Fig.  109),  established  by  Link  in  1809,  is  one  which 
has  come  into  prominence  recently  as  associated  with  the  production 
of  serious  plant  diseases.  At  least  eleven  species  are  found  on  the 
sweet  potato  (Fig.  108),  and  these  have  been  investigated  by  H.  W. 
Wollenweber^  and  other  mycologists.  He  finds  that  the  genus  has  a 
number  of  vegetative  and  spore  stages  the  variabihty  of  which  has 
caused  confusion,  as  transfers  of  mycehum  produce  a  growth  quite 
different  in  general  appearance  from  that  derived  from  spores  from  the 


Fig.  109. — Spores  of  two  stem-rot  organisms.  A,  Fusarium  bataiatis  and  B. 
F.  hyperoxysporum,  X500.  {After  Harter,  L.  L.,  U.  S.  Farmers"  Bull.  714,  March  11, 
1916.) 


same  medium  under  conditions  otherwise  identic.  'yVollenweber  and 
AppeP  have  pubUshed  a  monograph  of  Fusarium  and  later  Wollen- 
weber  has  studied  the  Fusarium  problem  and  similar  studies  should 
be  made  of  each  one  of  the  form  genera  of  the  Fungi  Imperfecti. 
The  genus  Fusarium  is  divisible  into  sections  not  only  by  physiologic 
characters  (pathogenicity)  but  also  by  morphologic  characters  (coni- 
diospores,  chlamydospores).  The  section,  Elegans,  comprises  the 
vascular  parasitic  Fusaria,  which  are  serious  enemies  of  plants,  causing 

1  WoLLENWEBER,  H.  W. :  Identification  of  Species  of  Fusarium  occurring  on 
the  Sweet  Potato,  Ipomaa  hatatis.  Journal  of  Agricultural  Research,  II:  251-286 
July  15,  1914. 

^Appel,  Otto,  and  Wollenwebek,  H.  W.:  Grundlage  einer  Monograph 
der  Gattung  Fusarium  Link  Arb.  Biol.  Anst.  f.  Land.  u.  Forst.,  Bd.  8,  Heft,  i, 
pp.  1-207;  Phytopathology  III:  24-50. 


2  68 


MYCOLOGY 


Fig.  1 10. — Violet  leaf  spot  {Fusarium  viola),  i,  Germination  of  microconidio- 
sporeS;  2,  formation  of  microconidiospores  in  hanging  drop  cultures;  3,  germination 
of  macroconidia;  4,  various  forms  of  macroconidia.  (.After  Mycologia,  2:  19-21,  pi. 
xviii,  January,  191  o). 


FUNGI   IMPERFECTI    (dEUTEROMYCETES)  269 

especially  wilt  diseases.  Fusarium  oxysporum  and  T.  trichorthecoides 
can  produce  both  tuber  rot  and  wilt  of  the  potato  plant.  Fusarium 
viola  causes  violet  leaf  spot  (Fig.  no).  Ftisarium  bat  at  atis  is  respon- 
sible for  sweet  potato  stem  rot  (Figs.  108  and  109). 

The  sterile  fungus  Rhizoctonia,  represented  in  America  by  two  para- 
sitic species  Rhizoctonia  solani,  which  is  found  on  at  least  165  different 
hosts,  and  R.  crocorum  with  a  limited  distribution  on  alfalfa  and  potato 
tubers  has  through  the  discoveries  of  Rolfs  and  Burt  been  connected 
with  a  basidiomycetous  fungus,  Corticium  vagum  var.  solani.^ 

1  Peltier,  George  L.  :  Parasitic  Rhizoctonias  in  America.  Bull,  189,  Agri. 
Exper.  Stat.  University  of  Illinois,  June,  1916. 


PART  II 
GENERAL  PLANT  PATHOLOGY 

CHAPTER  XXIII 
GENERAL  CONSIDERATION  OF  PLANT  DISEASES 

The  student  who  would  become  acquainted  with  the  general 
pathology  of  plants  must  have  some  previous  knowledge  of  other  sub- 
jects, especially  those  which  are  concerned  with  the  life  of  the  plant. 
To  appreciate  diseased  conditions  the  normal  state  of  the  plant  must 
be  understood.  A  study  of  phytopathology,  which  as  a  department  of 
scientific  inquiry  concerns  itself  with  plant  diseases,  therefore,  presup- 
poses that  the  would-be  phytopathologist  is  acquainted  with  plant 
morphology,  systematic  botany  (fungi  and  flowering  plants)  histology, 
cytology,  embryology,  genetics,  physiology,  with  bacteriology,  zoology 
(especially  entomology)  chemistry  and  physics,^  as  well  as  meteorology. 
Plant  morphology  deals  with  the  general  form  and  gross  structure  of 
plant  parts,  such  as  roots,  stems,  leaves,  flowers,  fruits  and  seeds.  The 
student  should  know  the  common  fungi  (see  part  I),  the  technique  of 
their  study  (see  part  IV),  as  well  as  the  flowering  plants,  which  act  as 
hosts  to  the  bacteria  and  fungi  causing  disease.  Histology  is  concerned 
with  the  microscopic  details  of  plants,  while  cytology  treats  of  cell 
structure  and  organization.  Embryology,  as  a  distinct  subject  of  in- 
quiry, embraces  a  study  of  their  productive  cells  and  organs.  Genetics 
is  a  new  branch  of  inquiry.  As  Walter  tersely  put  it,  "The  study  of  the 
origin  of  the  individual,  which  has  grown  out  of  the  more  general 
consideration  of  the  origin  of  species,  forms  the  subject  matter  of 
heredity,  or,  to  use  the  more  definitive  word  of  Bateson,  of  genetics." 
The  functions  of  a  plant  are  considered  when  we  study  physiology  and 
the  chief  divisions  of  that  subject  treat  of  the  nutrition,  growth  and 

1  Along  these  lines  see  suggestive  papers  by  Ernest  Shaw  Reynolds:  Plant 
Pathology  in  its  Relations  to  other  Sciences.  Science,  new  ser.,  xxvii:  937-940; 
June  19,  1908. 

271 


272  GENERAL   PLANT   PATHOLOGY 

irritability  of  the  living  plant  organisms.  A  knowledge  of  insect  life 
is  essential,  as  also  the  chemistry  of  the  plant,  of  the  soils,  of  the  ferti- 
lizers, of  the  insecticides  and  fungicides.  The  physics  of  sap  ascent, 
of  osmosis,  of  turgescence,  and  of  the  soil  must  be  studied.^ 

The  investigation  of  malformed  organs  and  cells  may  be  classified 
under  the  head  of  Pathologic  Morphology,  and  if  the  microscope  is 
used,  it  may  include  Pathologic  Histology  and  Pathologic  Cytology. 
Disturbed  conditions  of  the  reproductive  cells  and  organs  bring  about 
anomalies  in  the  offspring,  so  that  genetically  speaking  freaks,  bizarre 
forms,  or  chimeras  arise.  Diseased  conditions  may  be  traceable  to 
disturbed  nutrition,  to  excessive  or  retarded  growth  and  to  abnormal 
irritability.  Therefore  to  be  a  successful  pathologist,  one  must  be  a 
good  morphologist,  histologist,  geneticist  and  physiologist. 

Phytopathology  is  that  phase  of  botanic  inquiry  which  treats  of  the 
diseases  of  plants.  Its  history  dates  from  about  1850.  Disease  may  be 
looked  upon  as  an  unwholesome  condition,  derangement  of,  perversion 
of,  or  departure  from  the  normal  in  structure,  in  function,  or  in  both  com- 
bined. It  is  a  morbid  state.  One  who  studies  phytopathology  is  con- 
cerned with  the  characteristic  symptoms  of  disease  (Symptomatology), 
the  interpretation  of  symptoms  (Diagnosis),  with  the  causes  of  diseases 
(Etiology)  and  with  the  remedies  (Therapeutics)  and  prevention  of  dis- 
ease (Prophylaxis).  Recently  considerable  attention  has  been  given 
prophylaxis,  following  out  the  old  adage  that  an  ounce  of  prevention  is 
worth  a  pound  of  cure.     Curative  agents  are  therapeutic  agents. 

ETIOLOGY. — At  the  outset  it  is  important  to  consider  the  causes  of 
disease.  These  may  be  considered  under  two  heads,  predisposing  and 
determining. 

Predisposing  Causes  of  Disease. — The  normal  plant  can  to  a  cer- 
tain extent  ward  off  the  attack  of  disease,  but  the  power  to  do  so  varies 
within  wide  limits,  which  may  be  conditioned  upon  racial,  or  individual 
characteristics  of  resistance.  The  degree  of  this  resistance  determines 
the  degree  of  the  immunity  of  the  plant  organism.  It  is  well  known 
that  the  normal  constitution  of  plants  varies  considerably  in  individ- 
uals of  the  same  variety  and  among  different  races  and  varieties  of  the 
same  species.  Some  individuals  and  varieties  are  constitutionally  weak, 
others  are  strong  and  resistant  to  external  influences  of  every  descrip- 

iAppel,  O.:  The  Relations  between  Scientific  Botany  and  Phytopathology. 
Annals  Mo.  Bot.  Gard.,  2:  275-285,  February,  April,  1915. 


GENERAL   CONSIDERATION   OF   PLANT   DISEASES  273 

tion.  Such  plants  are  designated  as  cast-iron,  or  hardy,  while  the 
others  are  tender  and  need  constant  care  and  attention  on  the  part  of 
the  cultivator.  Such  weakness  of  constitution,  of  histologic  structure, 
or  absence  of  protecting  chemical  bodies  in  the  cells  of  the  plant  may  be 
looked  upon,  other  things  being  equal,  as  predisposing  causes  of  diseases. 
Such  depend  on  the  hereditary  character  of  the  plant,  and  in  case  of 
varieties  susceptible  to  disease  may  be  designated  hereditary  predis- 
position. Immunity,  on  the  other  hand,  may  be  hereditary,  as  in  the 
case  of  the  plants  of  strong  constitution,  or  acquired.  Resistance  on  the 
part  of  certain  plants  may  be  due  to  the  hereditary  resistance  of  the  pro- 
toplasm, it  may  be  due  to  histologic  structure,  such  as  the  presence  of  a 
thick  cuticle  in  the  resistant  form  and  its  absence  in  the  susceptible  form, 
for  Sorauer  has  found  that  the  resistance  of  different  carnations  was  due 
to  the  thickness  of  the  cuticle.  The  habit  of  earliness,  or  lateness,  may 
be  the  determining  factor  in  resistance.  A  late  variety  might  be  at- 
tacked, because  of  its  growth  in  relation  to  the  life  history  of  some  insect, 
or  fungous  parasite,  while  for  this  reason  an  early  variety  might  remain 
healthy.  Morphologic  peculiarities  may  be  effective,  for  the  investiga- 
tions of  Hecke  and  Brefeld  have  shown  that  in  the  varieties  of  wheat  with 
closed  flowers,  and  which  are  close  pollinated,  therefore,  the  spores  of 
the  loose  smut  fungus  carried  by  the  wind  are  unable  to  reach  the  stig- 
mas, and  hence,  infection  does  not  take  place.  Such  varieties  would  be 
smut  proof  for  the  simple  morphologic  reason  that  their  stigmas  are  not 
exposed  to  the  smut  spores.  Osterwalder  has  indicated  that  varieties 
of  pears  without  an  open  channel  from  the  calyx  to  the  carpels  are  pro- 
tected against  infection  by  Fiisarium  putrefaciens,  while  those  varieties 
with  an  open  channel  from  calyx  to  t"he  carpels  are  susceptible.  The 
habit  of  a  plant,  as  to  drying  after  a  rain,  may  influence  its  disease 
resistance,  as  shown  by  Appel.^  Infection  of  potatoes  by  the  spores  of 
late  blight,  Phytophthora  infestans ,  is  due  to  the  wind  carrying  the  spores 
to  healthy  plants  where  in  the  raindrops  on  the  surface  of  the  leaves 
zoospores  are  formed. 

The  leaves  of  some  varieties  dry  within  half  an  hour  after  a  rain, 
while  on  others  the  leaves  do  not  dry  for  several  hours.  Quick-drying 
varieties  are  less  susceptible  than  the  slow-drying  ones.  In  some  mem- 
bers of  the  pea  family,  the  seeds  are  imbedded  in  a  woolly  outgrowth  of 

^  Appel,  O.:  Disease  Resistance  in   Plants.     Science,  New  ser.,  xli:   773-782, 
May  28,  1915. 
iS 


274  GENERAL   PLANT   PATHOLOGY 

the  inner  epidermis  of  the  pod.  It  has  been  found  that  infection  of  the 
seeds  with  Ascochyta  pisi  is  facihtated  by  the  presence  of  the  hairs,  for 
the  fungus  grows,  as  in  a  culture  medium,  and  infects  every  seed,  while 
in  the  hairless  forms  infection  takes  place  only  where  the  seed  actually 
touches  the  infected  spot  of  the  pod. 

The  presence  of  certain  chemic  substances  may  explain  immunity,  for 
the  disease  resistance  of  Vaccinium  vitis  idcea  is  supposed  to  be  due  to  the 
presence  of  benzoic  acid.  So,  too,  the  presence  of  tannins  may  increase 
the  power  of  resistance  to  fungus  and  insect  diseases,  as  indicated  by 
Cook  and  Taubenhaus.'  Enzymes  also  play  an  important  role  in  the 
production  of  chemic  substances,  which  increase  disease  resistance. 
Such  hereditary  disease  resistance  may  be  made  to  play  an  important 
part  by  breeding  and  growing  the  varieties  which  have  been  proved  to 
be  disease  resistant. 

Immunity  may  be  acquired  by  growing  the  susceptible  form  at  a 
different  season  of  the  year  from  its  accustomed  one.  Grafting  has 
been  used  with  success.  The  method  is  to  graft  a  non-resistant  variety 
on  a  resistant  one,  as  in  the  case  of  the  European  vine  on  the  American 
vine,  which  resists  the  attack  of  the  Phylloxera  insect,  which  devastated 
the  European  vineyards  until  this  method  was  adopted.  Crossing  has 
been  resorted  to  as  a  second  means  of  increasing  disease  resistance.  The 
weak  variety  is  crossed  with  a  disease  resistant  form  to  increase  its 
immunity.  The  third  way  to  obtain  immune  forms  is  to  select  resistant 
individuals  and  from  them  breed  pure  strains.  This  has  been  accom- 
plished with  some  degree  of  success  by  Orton  with  cotton,  by  BoUey 
with  flax,  by  L.  R.  Jones  with  cabbage.  It  should  be  emphasized  that 
the  inheritance  of  the  unit  characters  and  their  behavior  in  the  next 
generation  is  one  of  the  fundamentals  of  breeding  resistant  races. 

Determining  Causes. — Having  considered  the  general  reasons  for  the 
predisposition  of  plants  to  diseases  and  the  immunity  of  others,  it  is 
important  to  describe  next  the  causes  which  determine  disease.  These 
may  be  divided  into  those  of  external  origin  and  those  ofinternal.  The 
external  factors  of  disease  are  the  chemical  conditions  of  the  soil,  as  a 
determining  cause,  also  the  physical  character  of  the  soil.  The  influ- 
ence of  a  superabundance  of  water,  or  its  absence,  is  important.     Cli- 

^  Cook,  Mel  T.  and  Taubenhaus,  J.  J.:  The  Relation  of  Parasitic  Fungi  to  the 
Contents  of  the  Cells  of  the  Host  Plants,  i.  The  Toxicity  of  Tannin,  BuU.  91, 
Delaware  College  Agric.  Exper.  Stat.,  Feb.  i,  1911. 


GENERAL   CONSIDERATION    OF   PLANT   DISEASES 


275 


matic  and  meteorologic  conditions  may  be  influential,  when  these  dis- 
turb the  normal  life  of  the  plant.  Light,  heat,  cold,  rain,  dew,  hail, 
frost,  wind  and  Ughtning  play  an  important  role.  The  gaseous  emana- 
tions from  gas  pipes,  smelter  works,  smokestacks,  including  soot,  dust 
from  cement  works,  acids,  poisons,  and  dye  stuffs,  which  pollute  streams, 
all  are  determining  causes  of  disease.  Traumatism  or  mechanic  injury 
may  be  of  various  sorts  and  the  effects  are  dependent  upon  the  form  and 
severity  of  the  injury,  or  wound. 


Fig.  III. — Rose-chafer  {Macrodaclylis  subspinosus).  a.  Adult  or  beetle;  b, 
larva;  c,  d,  mouth  parts  of  same;  e,  pupa,  /,  injury  to  leaves  and  blossoms  of 
grape  with  heetles  at  work.  {From  Marlalt  in  Quaintance,  A.  L.  and  Shear,  C.  L., 
U.  S.  Farmers'  Bull.  284,  1907.) 


Living  organisms,  whether  animal  or  vegetal,  may  be  the  cause  of 
disease.  All  groups  of  animals  may  be  considered,  but  the  mammals, 
worms  and  insects  (Fig.  iii)  are  of  most  importance  and  interest. 
Insect  depredations  of  plants  are  notorious  and  insects  occupy  first 
place  in  their  destructive  effects  on  plants  (Fig.  112).  Various  para- 
sitic flowering  plants  are  known,  as  well,  as  the  bacteria  and  fungi, 
for  their  disease-producing  powers. 


276 


GENERAL  PLANT  PATHOLOGY 


As  an  internal  determining  cause,  the  formation  of  enzymes  under 
abnormal  conditions  must  be  reckoned  as  causal,  as  well,  as  nutritive 
disturbances  which  produce  monstrosities  and  the  like. 

Having  classified  the  chief  causes  of  disease,  a  more  detailed  descrip- 
tion of  these  factors  should  be  put  in  a  form  available  for  student  use. 
Much  of  the  information  is  scattered,  and  part  of  it  is  buried  in  foreign 
botanic  and  pathologic  journals,  which  can  be  consulted  only  in  the 
largest  scientific  hbraries  at  home  and  abroad. 


Fig.  112. — Oyster-shell  scale  {Lepidosaphes  ulmi.     After  Quaintance,   A. 
Farmers'  Bull.  723,  Apr.  26,  1916. 


L.,   U.  S. 


The  chemic  condition  of  the  soil,  as  a  determining  cause  of  disease, 
may  be  considered  from  the  standpoint  of  the  normal  influence  of  the 
important  soil  ingredients,  as  contrasted  with  the  absence  or  deficiency 
of  such  elements.  Potassium  is  usually  found  in  young  tissues  and  dis- 
appears in  the  older  ones.  It  is  associated  in  some  way  with  the  for- 
mation of  carbohydrates  in  the  plant  such  as  starch,  sugar  and  cellulose. 
The  absence  of  potassium  in  the  soil  causes  a  cessation  of  growth,  the 
leaves  fail  to  develop  the  power  of  forming  starch  within  the  greenr 
coloring  bodies,  or  chloroplasts.  A  plant  which  has  failed  to  grow  for 
months  will  recover  in  a  few  days  after  potassium  salts  have  been  added 


GENERAL    CONSIDERATION    OF    PLANT    DISEASES  277 

and  after  a  few  hours  the  formation  of  starch  in  the  chloroplasts  will 
be  detected.^  The  storage  of  reserve  materials  is,  therefore,  inhibited, 
and  one  finds  in  such  plants,  as  the  cereals,  that  the  formation  of  green 
parts  is  at  the  expense  of  the  grain,  and  in  the  beet,  the  vegetative  part  of 
the  plant  is  at  the  expense  of  the  fleshy  roots.  Potassium  hunger  causes" 
in  the  potato  and  buckwheat  a  shortening  of  the  internodes  and  a 
convex  bending  of  the  leaf  blades,  which  are  spotted  with  yellow  blotches. 
Calcium  is  abundant  in  nature  in  the  form  of  the  carbonate  which 
forms  the  rocks  known  as  marble  and  limestone.  It  is  chiefly  concerned 
in  the  strengthening  of  the  cell  wall,  where  in  such  plants  as  Chara  it  is 
deposited.  It  plays  an  important  role  in  fixing  the  calcium  oxalate 
formed  in  the  metabolism  of  the  plant.  Ecologists  in  Europe  classify 
many  plants  either  as  calciphile  (calcium-requiring),  or  calciphobe 
(calcium-hating).  The  apphcation  of  calcium  to  soils  under  certain 
conditions  promotes  apparently  the  disease  of  beets  called  heart-  or 
dry  rot.  The  chlorosis,  or  icterus,  of  the  grape  vine  seems  to  be  in- 
creased in  soils  with  a  high  calcium  content.  The  accumulation  of 
oxalic  acid  in  the  absence  of  its  fixation  by  calcium  poisons  the  plant. 
The  formation  of  brown  blotches  on  leaves,  the  yellowing,  or  brown- 
ing of  pine  needles,  the  death  of  the  root  tips  of  water  plants  is  associated 
with  the  absence  of  calcium. 

Magnesium  is  chemically  allied  to  calcium,  but  it  cannot  replace 
calcium  in  the  economy  of  the  plant.  It  apparently  works  together 
with  nitrogen  in  the  formation  of  protoplasm,  and  has  an  influence  in 
the  formation  of  chlorophyll,  for  plants  grown  without  magnesium  have 
yellowish-green  chloroplasts,  and  new  cell  formation  does  not  proceed 
readily.  The  absence  of  magnesium  is  shown  in  the  pale-green  color 
of  the  chloroplasts,  the  yellow  to  orange-yellow  blotches  on  the  leaves, 
and  the  brown  spots  on  the  stems.  The  amount  of  starch  formed  by 
the  chloroplasts  is  reduced,  the  internodes  are  shortened,  the  young 
leaves  do  not  unfold.  These  are  symptoms  associated  with  a 
deprivation  of  magnesium. 

Iron  is  necessary  in  the  formation  of  chlorophyll,  for  if  the  plant  is 
grown  in  an  iron-free  solution,  it  remains  permanently  etiolated 
(blanched).  The  diseased  condition  which  arises  through  the  lack  of 
the  requisite  amount  of  iron  is  called  chlorosis.  Too  much  iron  in  the 
soil  acts  poisonously. 

^Hartwell,  B.  L.:  Bull.  165,  R.  1.  Agric.  Exper.  Stat.,  May,  1916. 


278  GENERAL   PLANT   PATHOLOGY 

Sulphur  and  phosphorus  are  of  some  value  in  the  production  of 
albuminous  substances  by  the  plant,  and  in  the  soil  they  exist  mainly 
as  calcium  sulphate  and  calcium  phosphate.  Phosphorus  is  in  some 
way  associated  with  the  formation  of  the  crystalloids,  globoids  and 
aleurone  grains  of  the  plant.  Some  soils  are  poor  in  phosphorus,  so 
that  the  agriculturist  must  supply  phosphates.  The_  deficiency_of 
phosphorus  is  seen  in  the  production  of  a  red  coloration  in  plarits.  The 
leaves  are  blotched  with  red  and  later  the  spots  become  dark  brown. 
The  formation  of  flowers  and  seeds  is  partially  inhibited.  The  absence 
of  sulphur  is  manifest  in  the  poor  development  of  the  whole  plant  and 
in  the  reduction  in  the  amount  of  fruit  produced. 

Nitrogen  enters  largely  into  the  living  substance  of  the  plant, 
protoplasm.  It  is  stored  in  the  form  of  protein  granules  and  aleurone 
grains.  In  the  life  of  the  plant,  it  is  concerned  in  the  building  of  young 
tissues,  and  in  the  metabohsm  of  plants,  it  appears  in  the  form  of  aspar- 
agin  which  in  the  soluble  state  is  conducted  through  the  bast  portions 
of  the  vascular  bundles  from  one  part  of  the  plant  to  another  part. 
Some  plants  have  a  pecuhar  relationship  to  nitrogen.  Such  are  the 
leguminous  plants,  which  are  provided  with  root  nodules,  where  there 
are  nests  of  bacteria.  These  bacteria  can  utiUze  free  atmospheric  nitro- 
gen and  later  in  the  involution  form  as  bacteroids,  they  are  absorbed 
by  the  green  plant  which  is  thus  enriched  with  nitrogen.  During  the 
period  of  entrance  of  bacteria  into  the  root  hairs,  the  young  seed- 
ling goes  through  a  period  of  nitrogen  starvation,  when  it  appears 
to  flag,  but  later,  it  regains  its  active  growth  and  vitality  when  the 
nodules  have  been  formed.  Contrasted  with  the  same  leguminous 
species  without  nodules  and  when  the  root  systems  alone  take  up 
nitrogen  in  the  form  of  nitrates,  the  nodulated  plant  is  larger  and 
stronger  in  every  respect. 

A  deficiency  of  nitrogen  in  the  soil  can  be  detected  in  the  case  of 
Indian  corn  and  other  agricultural  plants  by  a  general  paling  of  the 
green  color,  so  that  in  some  cases  the  plant  becomes  yellowish-green. 
Klebahn^  indicates  that  the  leaves  of  beets,  buckwheat  and  potatoes 
assume  a  yellowish  color  with  a  deficiency  of  nitrogen,  and  as  the  leaves 
dry,  they  become  yellowish-brown.  The  prothaUia  of  ferns  in  a  nitrogen- 
free  nutritive  solution  do  not  form  meristem  or  archegonia.  Excessive 
supplies  of  nitrates  in  their    application    to  cultivated  fields  stimu- 

1  Klebahn,  Prof.  D.  H.:  Grundzuge  der  Allgemeinen  Phytopathologie,  1912: 11. 


GENERAL   CONSIDERATION   OF   PLANT   DISEASES  279 

lates  in  the  case  of  the  crops  grown  upon  such  fields  the  development 
of  the  vegetative  organs  and,  therefore,  delays  the  formation  of  flowers 
and  fruit  and  the  ripening  of  seeds.  Such  delay  may  mean  the  attack 
of  parasitic  fungi.  For  example,  a  large  field  of  winter  wheat  which 
had  been  sown  about  the  end  of  October  was  much  attacked  by  stink- 
ing smut  (60  per  cent.),  while  the  adjacent  fields  belonging  to  the  same 
farmer,  under  the  same  variety  of  wheat  and  treated  in  a  similar 
manner,  but  sown  early  in  October  showed  no  sign  of  infection.  With 
fruit  trees,  one  notices  greater  frost  susceptibility  in  those  plants  which 
have  received  an  excessive  nitrogen  supply.  Lipman  (Science,  new 
ser.  xxxix:  728-730,  May  15,  1914)  has  suggested  that  the  poor  nitri- 
fying power  of  soils  is  a  possible  cause  of  "die-back"  (exanthema)  in 
lemons.  It  has  been  a  serious  disease  with  the  citrus  growers  of 
Florida  and  California. 

Physical  Character  of  the  Soil.- — The  physical  character  of  the  soil 
is  of  great  importance  as  a  determining  cause  of  disease.  When  we 
speak  of  the  physical  character  of  the  soil,  we  refer  to  the  size  of  its 
particles,  the  relation  of  these  particles  to  each  other,  the  presence 
of  colloidal  bodies,  the  presence  of  air  spaces  associated  with  the  air 
content,  the  distribution  of  the  water  through  the  soil,  the  presence  or 
absence  of  organic  matter,  or  humus,  the  color  and  temperature  of  the 
soil.  Of  greatest  importance  to  the  life  of  the  plant  is  the  water 
which  is  available  for  the  needs  of  the  plant. ^  A  too  plentiful  sup- 
ply of  water  causes  the  formation  of  a  wet  ball  of  roots  with  the 
formation  of  alcohol.  Frequently  gardeners  fearing  that  the  soil  is 
dry,  water  potted  plants  with  more  water  than  the  plants  actually 
need,  so  that  the  lower  part  of  the  soil  is  continuously  saturated  with 
water.  Alcohol  is  formed  and  decay  of  the  roots  sets  in,  because  they 
are  gradually  suffocated.  Too  little  water  on  the  other  hand  causes 
a  drooping  or  wilting  of  the  plant,  and  if  water  is  not  supplied  in 
time  permanent  wilting  and  death  of  the  foliage  results.  But  a 
diminished  water  supply  may  be  decidedly  beneficial  to  plants,  as  it 
has  been  found  that  the  formation  of  flower  buds  is  best  initiated  by 
preserving  a  period  of  rest  following  a  diminished  water  supply. 
Different  plants  have  different  water  requirements  and  these  require- 
ments  vary  with   the   season  of   the  year  and  the  development  of 

*  Cf.  SoRAUER,  Paul,  Lindau,  G.  and  Reh,  L.,  transl.  by  Dorrance,  Frances: 
Manual  of  Plant  Diseases,  vol.  i,  parts  i  and  2. 


28o  GENERAL   PLANT   PATHOLOGY 

the  plant.  As  an  illustration  of  this  may  be  cited  the  planting  of  the 
Carolina  poplar  on  the  open  porous  sandy  soils  of  New  Jersey.  About 
Philadelphia,  where  the  tree  is  largely  planted,  it  grows  rapidly  with 
a  dense  crown  of  dark-green,  foliage  leaves.  In  New  Jersey,  it  grows 
less  rapidly,  its  crown  is  more  open  by  a  wider  spacing  of  the  branches 
and  the  leaves  have  a  greenish-yellow  appearance  and  drop  off  earlier 
in  the  autumn  than  similar  trees  on  the  Pennsylvania  side  of  the  Dela- 
ware River.  This  difference  is  without  doubt  associated  with  the  water 
requirements  of  the  tree,  for  on  the  Pennsylvania  soils,  it  can  secure 
abundance  of  water  during  the  growing  season,  while  in  the  New  Jersey 
sands,  owing  to  their  porosity  and  the  rapid  drainage  of  water  through 
them,  the  Carolina  poplar  does  not  receive  sufl&cient  amounts  of  water 
for  its  most  vigorous  growth. 

The  experiments  of  Miinch^  throw  important  light  on  the  content 
of  water  and  air  in  the  tissues  as  a  determining  factor  of  disease  of 
woody  plants,  such  as  on  forest  and  fruit  trees.  He  has  shown  that  the 
greater  number  of  the  wood-destroying  fungi  require  a  large  amount  of 
air  and  are  able  to  grow  only  when  a  maximum  amount  is  present.  The 
air  content  of  the  tissues  is  dependent  on  the  water  supply  and  trees 
with  narrow  annual  rings  are  more  resistant  than  those  with  broad  ones, 
because  the  former  contain  m.ore  water  and  less  air  relatively.  Differ- 
ent annual  rings  of  the  same  tree  may  be  attacked  differently. 

The  decayed  rings  of  wood  in  such  trees  are  always  the  broad  ones. 
The  tissues  of  vigorous  branches  are  rich  in  water  and  poor  in  air  and 
infections  do  not  always  penetrate  to  such  regions.  The  healthy  bark 
of  beech  trees  in  winter-rest  contains  19  to  20  per  cent,  of  air  and  at 
the  time  of  budding  the  air  diminishes  to  11  per  cent.,  rising  afterwards; 
This  is  correlated  with  the  canker  disease,  Nectria  ditissima,  which  in 
Europe  does  its  damage  during  the  winter  months,  while  during  the 
vegetative  period  it  ceases.  Hence,  we  have  opened  here  a  very  profita- 
ble line  of  investigation  to  determine  the  relative  amounts  of  air  and 
water  with  respect  to  immunity,  or  its  absence.  Again,  in  the  irrigated 
districts  of  America,  the  fruit  trees  have  only  a  few  diseases  due  to 
species  of  Valsa  and  other  species  of  fungi.  Defective  irrigation  may 
bring  about  the  prevalence  of  the  die-back  diseases,  which  may  be  reme- 

^MtJNCH,  E.:  Untersuchungen  iiber  Immunitat  und  Krankheitsempfanglich- 
keit  der  Holzpflanzen.  Naturwiss.  Zeitsch.  f.  Forst.  und  Landw.,  7:  54-75,  87- 
114,  129-160,  1909;  Appel,  O.:  Phytopathology  &  Scientific  Botany,  loc.  cit. 


GENERAL    CONSIDERATION    OF    PLANT    DISEASES  251 

died  by  changing  the  system  of  irrigation.  The  land  should  be  irri- 
gated at  the  time  when  the  trees  contain  small  amounts  of  water  and 
much  air,  so  as  to  prevent  an  excessive  decrease  of  water  in  the  tissues. 

The  condition  of  the  humus  has  a  rather  remarkable  influence  on 
the  growth  of  plants.  Ericaceous  plants,  such  as  the  trailing  arbutus 
{EpigcEa  repens),  wintergreen  {Gaultheria  procumbens),  bearberry 
(Arctostaphylos  iiva-iirsi),  blueberry  {Vaccinium  corymhosum)  flourish 
in  an  acid  humus  and  if  the  attempt  is  made  to  grow  such  plants 
under  other  conditions,  they  languish  and  die.  Other  species  like  In- 
dian turnip  {Ariscema  triphylla),  blood  root  (Sanguinaria  canadensis), 
rue  anemone  {Anemonella  thalidroides)  grow  best  in  a  leaf- mould  humus 
which  is  neutral  or  slightly  alkaline.  Reverse  the  reaction  of  the  soils 
about  these  plants  and  they  gradually  die. 

The  presence  of  an  impervious  hard  pan  below  the  surface  soil  is 
a  condition  which  prevents  the  normal  development  of  trees,  as  I  have 
shown  in  my  book  on  the  "Pine  Barren  Vegetation  of  New  Jersey," 
where  in  the  region  known  as  the  Plains,  the  pitch-pine  trees  are  kept 
dwarf  owing  to  an  impervious  subsoil  layer.  There  the  trees  flourish 
for  a  number  of  years,  then  begin  to  suffer  until  unable  to  penetrate  the 
deeper  layers  of  the  soil,  they  finally  succumb  to  be  replaced  by  younger 
trees  which  meet  the  same  fate. 

Climatic  and  Meteorologic  Factors. — The  most  important 
climatic  factors,  which  may  be  looked  upon  as  in  any  way  related  to 
disease  production,  are  light,  heat,  precipitation  (rain,  dew,  frost,  snow, 
hail  and  ice)  wind  and  electricity  (lightning,  etc.). 

Light  is  essential  for  the  life  functions  of  all  green  plants.  Carbon 
dioxide  and  water  are  united  by  the  energy  of  sunlight  to  form  starch. 
The  synthesis  takes  place  in  the  chloroplast,  starch  being  formed  as 
the  first  visible  product.  Ordinary  sunlight  of  a  bright,  clear  day  may 
under  certain  conditions  of  plant  growth  be  too  intense  and  it  acts 
prejudicially.  The  writer  has  frequently  noted,  that  garden  plants 
suffer,  if  after  a  wet,  cloudy  spell  during  the  rapid  period  of  growth, 
they  are  exposed  to  a  bright  sun  without  protection.  It  takes  a  few 
days  of  bright  light  to  sun-harden  the  plants.  Trees,  especially  with 
a  smooth  bark,  which  have  grown  in  a  very  dense  wood,  and  then 
suddenly  isolated  in  later  life,  suffer  from  scorching  of  the  cortex. 
They  are  sunburned.  Plants  grown  in  greenhouses,  which  have  been 
painted  with  whitewash  to  reduce  the  intensity  of  the  rays  of  light,  have 


282  GENERAL   PLANT   PATHOLOGY 

their  leaves  burned  if  part  of  the  whitewash  is  removed.  The  light 
passes  through  the  opening  thus  made  and  the  leaves  on  which  it  is 
concentrated  are  scorched. 

Several  diseases  of  plants  are  caused  by  too  brilliant  sunlight.  Such 
are  sunscald,  sunscorch  and  bronzing.^  Sunscald  may  follow  as  a 
result  of  too  intensive  sunlight,  as,  for  example,  when  certain  fruit  trees 
are  stripped  of  their  foliage  in  summer,  such  as  sometimes  results  from 
the  ravages  of  the  gypsy  moth.  In  such  instances  the  new  unripened 
wood  sunscalds  badly.  Sometimes  it  is  associated  with  severe  and 
abrupt  changes  in  temperature  on  non-ripened  wood.  "Sunscorch" 
is  a  term  applied  to  the  burning  of  foliage  in  summer  during  periods 
when  the  soil  is  dry,  and  is  also  common  to  evergreens  during  warm 
wiildy  days  in  spring  before  the  frost  is  out  of  the  ground.  Any 
defects  in  the  root  system  which  prevent  root  absorption  may  cause 
sunscorch.  "Bronzing"  of  leaves  is  a  form  of  sun  scorch  characterized 
by  the  occurrence  of  a  reddish-brown  or  bronze  color  of  the  leaf.  It  is 
caused  by  a  lack  of  soil  moisture,  or  defective  root  absorption  during 
dry,  hot  periods. 

Too  much  shade  is  also  detrimental  to  plants,  as  is  seen  under  the 
dense  canopy  of  beech  trees  on  a  lawn,  where  nothing  will  grow,  not 
even  a  blade  of  grass.  The  grasses,  etc.,  die  of  inanition.  The  condi- 
tion known  as  etiolation  originates  where  a  plant  is  grown  in  the  dark, 
or  in  subdued  sunlight.  Growth  in  darkness  leads  to  important  modi- 
fications in  the  general  habit  and  structure  of  a  plant.  If  we  take  a 
potato  plant  and  raise  it  in  the  dark,  we  find  the  etiolated  shoot  has 
a  white  stem  and  leaves  which  are  at  first  pinkish,  and  subsequently 
pale  yellow,  and  the  absence  of  chlorophyll  is  noteworthy.  The  inter- 
nodes  are  long  and  slender  and  the  leaves  are  small  compared  with  the 
green  plant  and  there  are  corresponding  anatomic  differences.  Morn- 
ing glories  raised  in  greenhouses  in  the  winter  do  not  twine.  They 
grow  from  four  to  five  inches  tall  and  have  only  one  to  two  flowers. 

Heat  as  a  factor  in  the  growth  of  plants  is  well  known.  Each  plant 
has  its  minimum,  maximum  and  optimum  degree  of  heat.  The  dis- 
tribution of  plants  over  the  larger  stretches  of  the  earth's  surface  is 
associated  with  the  amount  of  heat  that  the  different  plants  receive. 
The  absence  of  heat,  where  the  plant  is  exposed  to  a  temperature  below 

1  Stone,  George  E.:  Injury  to  Vegetation  Resulting  from  Climatic  Conditions. 
Monthly  Weather  Review,  44:  569-570,  October,  1916. 


GENERAL   CONSIDERATION   OF   PLANT   DISEASES  283 

freezing,  is  noteworthy.  The  death  of  cells  rich  in  water,  when  exposed 
to  low  temperatures,  seems  to  depend  upon  the  conversion  of  the  water 
extruded  into  the  intercellular  spaces  into  ice.  The  parenchymatous 
tissues  are  ruptured  and  crystals  of  ice  are  formed.  The  water,  there- 
fore, which  is  in  the  cell  reaches  the  surface  and  the  cell  sap  diminishes 
in  amount  and  there  may  be  chemic  changes  in  the  cell  as  a  result  of 
freezing,  for  in  some  cases  .the  leaves  assume  a  leathery  brown  color. 
Long  exposure  to  cold  may  lead  to  the  actual  disorganization  of  the 
protoplasm.  It,  however,  does  not  always  follow  that  the  formation 
of  ice  in  the  intercellular  spaces  necessarily  involves  death.  Slow 
thawing  may  be  followed  by  a  return  of  the  water  to  the  cells  until 
the  normal  equilibrium  is  restored  and  the  cells  continue  to  live.  A 
rapid  thawing,  however,  causes  death  of  the  cells,  because  the  water  is 
not  reabsorbed.  Frost-killed  twigs  and  branches  are  more  susceptible 
to  the  entrance  of  saprophytic  fungi  such  as  species  of  Nectria,  Dasy- 
scypha,  and  Valsa.  The  exposure  of  roots  during  a  snowless  winter 
may  lead  to  their  disturbance  by  freezing.  The  anatomic  changes 
induced  by  freezing  are  frost  blisters,  such  as  appear  on  the  leaves  of 
fruit  trees  and  cereals,  and  frost  cracks,  which  may  ultimately  heal 
over,  producing  an  external  ridge  or  enlargement.  The  fruit-grower 
can  distinguish  four  kinds  of  winter  injury  to  his  trees.  First,  the 
frosting  of  the  blossoms  after  they  begin  to  open;  second,  the  freezing 
of  the  buds  in  winter;  third,  the  freezing  of  the  twigs  and  branches; 
fourth,  root  freezing.  It  may  happen  that  early  in  the  spring  the 
peach  trees  come  into  bloom.  Then  on  a  cold  cloudless  night  with  no 
wind  the  temperature  sinks  below  freezing  and  the  partially  open 
flower  buds  are  nipped  by  the  frost.  About  twenty  years  ago  the 
upper  Mississippi  Valley  was  visited  by  an  unusual  cold  wave.  The 
frost  penetrated  to  great  depths  and  the  cold  was  so  intense  that  the 
tree  roots  were  actually  frozen  in  the  soil.^ 

The  formation  of  ice  fringes  upon  plants  has  been  investigated 
exhaustively  by  Coblentz,-  with  the  dittany,  Cunila  mariana.     He 

*  Consult  Waugh,  Frank  A.:  Jack  Frost's  Tricks.  The  Country  Gentleman, 
Feb.  6,  1915,  p.  213.  Wilson,  Wilford  M.:  Frosts  in  New  York.  Bull.  316, 
Cornell  University  Agri.  Exper.  Stat.,  June,  191 2.  Chandler,  W.H.:  The  Kill- 
ing of  Plant  Tissue  by  Low  Temperatures.  Research  Bull.  8,  Coll.  of  Agric, 
Univ.  of  Mo.,  Dec,  1913. 

2  Coblentz,  Wm.  W.  :  The  Exudation  of  Ice  from  Stems  of  Plants.  Monthly 
Weather  Review,  42:  490-499,  August,  1914. 


284  GENERAL    PLANT    PATHOLOGY 

found  that  the  ice  fringes  are  formed  when  the  temperature  falls  to 
freezing.  They  are  formed  on  the  outer  surface  of  the  plant.  The 
growth  of  the  ice  fringe  ceases  when  the  ground  is  frozen  to  a  depth  of 
2  to  3  cm.  and  when  the  moisture  in  the  stem  is  frozen.  The  dimen- 
sions of  the  fringe  depend  upon  the  rate  of  evaporation  of  water  from 
the  stem  up  which  it  rises  by  capillary  action  and  upon  the  amount 
of  moisture  in  the  ground.  Clouds  and  fogs  in  some  regions  have  an 
important  effect  on  vegetation.^  The  two  forms  of  foliage  leaves  on 
the  branches  of  the  redwoods  of  California  are  conditioned  upon  the 
height  of  the  fogs  which  drift  in  from  the  Pacific  Ocean.  The  leaves 
on  the  fog-exposed  branches  are  flat  and  divergent,  while  those  on  the 
sun-exposed  branches  above  the  fog  level  are  scale-like  and  appressed. 
The  London  fogs  work  detrimentally  to  outdoor  and  greenhouse  plants, 
and  in  Egypt,  the  cotton  capsules  long  exposed  to  fog  are  more  in- 
fested with  black  moulds.  Dew,  which  lodges  on  the  margins  of  leaves, 
is  responsible  for  the  entrance  of  fungi  by  their  spores  lodging  in  the 
dewdrops  and  germinating  there. 

The  weight  of  snow  and  ice  breaks  off  the  limbs  of  trees,  breaks  down 
herbaceous  plants,  and  this  opens  up  the  way  for  the  entrance  of 
various  parasitic  fungi.  Ice  or  sleet  storms  are  especially  severe  at  times 
to  trees.  The  year  1902  was  noted  for  two  exceptionally  destructive 
ice  storms  which  visited  the  Philadelphia  region.  One  of  these  storms 
occurred  on  Friday,  Feb.  21,  and  the  other  on  Saturday,  Dec.  13.^  The 
storm  of  Feb.  21  was  accompanied  by  high  winds  and  did  an  irreparable 
damage  to  the  fruit,  forest  and  shade  trees.  Meteorologically  speaking, 
regions  of  strongly  variable  temperature  are  subject  to  occasional 
winter  storms  in  which  the  precipitation  occurring  as  rain,  freezes  as 
soon  as  it  touches  any  solid  body,  such  as  the  branches  of  trees,  telegraph 
wires  or  the  ground.  This  happens  when  the  ground  and  the  lower 
air  have  been  made  excessively  cold  during  a  spell  of  clear  anticyclonic 
weather,  when  a  moist  upper  current  in  advance  of  an  approaching 
cyclone  brings  clouds  and  rain.  All  our  meteorologists  prefer  to  call 
such  storms  ice  storms;  locally  near  Philadelphia  they  are  denominated 
sleet  storms.     The  weight  of  ice  which  such  limbs  carry  is  astounding. 

1  Weiss,  F.  E.,  Imms,  A.  D.,  Robinson,  W.:  Plants  in  Health  and  Disease, 
1916;  54-56. 

"  Harshberger,  John  W.  :  Relation  of  Ice  Storms  to  Trees.  Contrib.  Bot. 
Lab.  Univ.  of  Penna.,  II:  345-349,  1904. 


GENERAL    CONSIDERATION    OF    PLANT    DISEASES 


285 


The  author  found  the  weight  of  a  branch  of  Liriodendron  tuUpiJera  with 
ice  upon  it  to  be  50  grams,  without  ice  9  grams;  so  that  the  ice  weighed 
41  grams,  giving  a  ratio  of  i  :  4.5.  Juniperus  virginiana  with  its  ice 
load  weighed  310  grams,  without  ice  13  grams,  making  the  weight  of  ice 
297,  a  ratio  of  i  :  23.  Beginning  with  Dec.  5,  1914,  a  combination 
rain,  snow  and  ice  storm  swept  across  the  Eastern  States  doing  much 


0 


10 


12 


13 


'^        H@        '5®     '^® 


17 


□Z2ZZ2 


Fig.  113. — Sectional  view  of  twigs  and  leaves  of  various  plants  showing  load  of 
ice  carried  during  the  ice  storm  of  Feb.  12  and  13,  1916.  i,  Acer  plalanoides;  2, 
blade  of  grass;  3,  Chionanthiis  virginicus;  4,  Diervilla  florida;  5,  Forsythia  suspensa; 
6,  Liguslrum  vulgare;  7,  Liriodendron  lulipifera;  8,  Platanus  orientalis;  9,  Populus 
alba;  10,  Populus  delloides;  11,  Quercus  paluslris;  12,  Syringa  vulgaris;  13,  Tilia 
americana;  14,  Tecotna  radicans;  15,  xanthoceras  sorbifolia;  16,  Spiraea  Thunbergii; 
17,  leaf  of  Rhododendron  maximum;  18,  icicle  on  tip  of  Rhododendron  maxifnum, 
leaf  hanging  down. 

local  damage^  and  again  on  Friday,  Dec.  31,  a  severe  ice  storm  visited 
the  mountain  region  of  Pennsylvania  contiguous  to  the  Juniata  Valley 
and  Susquehanna  River.  During  the  afternoon  of  Saturday,  Feb.  12, 
191 6,  a  cold  rain  began  which  continued  well  into  the  night,  coating  the 
pavements,  streets,  and  trees  with  hard  ice.  On  Sunday  morning, 
Feb.  13,  men,  boys  and  girls  took  advantage  of  the  icy  streets  to  skate 
1  Illick,  J.  S.:  A  Destructive  Snow  and  Tee  Storm.  Forest  Leaves,  xv:  103- 
107,  Fehriiari',  tqi6. 


286 


GENERAL   PLANT   TATHOLOGY 


upon  them  and  this  unusual  sight  was  stopped  by  a  snow  storm,  which 
followed  on  Sunday  morning.  The  trees  were  loaded  to  the  breaking 
point.  During  the  continuance  of  the  storm,  small  branches  were 
taken  oflf  thirteen  trees  and  shrubs  and  a  blade  of  grass  growing  in  West 
Philadelphia,  and  the  thickness  of  ice  upon  them  measured  with  a 
pair  of  compasses.  The  accompanying  figures  drawn  life  size  show  the 
relative  thickness  of  the  load  of  ice  borne  by  the  twigs,  whose  thickness 
is  shown  in  the  drawings  (Fig.  113). 


Fk,        Mi 

water  ni-ai    the  builacc 
L.  I.,  July.  1915. 


t  liii    I  h)nt\  iiDii  I  h  tiiui    ]iIl  ntifully  supiilicd  with  ground 
dcprcbbiuu  ot  the  glacial  uutwash  plain  at  Westbury, 


The  fall  of  hail  stones  may,  if  they  are  large  enough,  cause  the 
decortication  of  twigs,  or  the  abrasion  of  other  plant  parts,  thus  per- 
mitting the  entrance  of  destructive  bacteria  and  fungi  to  the  interior 
of  the  plants. 

Wind  is  an  active  agent  in  the  breaking  off  of  buds  and  limbs  and 
the  formation  of  dangerous  wounds.  In  such  situations,  as  high  moun- 
tains, sand  dunes  and  rocky  shores,  where  trees  are  exposed  to  the 
forcible  action  of  the  wind,  they  assume  a  windswept,  bisected,  or 
prostrate  form,   which  is  characteristic  and    picturesque   (Fig.    16). 


GENERAL   CONSIDERATION   OF   PLANT   DISEASES  287 


Fig.  115. — Unhappy  vase-shapei.l  white  elm,  I'ini:,  ,,  ',  .  ,  <,..>i.  luo  yards  south 
of  a  happy  larger  elm  both  growing  on  the  outwashed  plain,  Westbury,  L.  I.,  July, 
1915- 


Fig.   116. — Wind-swept  white  poplar,  Populus  alba,  Nantucket,  Mass.,  August,  1915. 


288  GENERAL   PLANT   PATHOLOGY 

Strong  winds  increase  the  amount  of  transpiration,  so  that  fre- 
quently we  find  there  is  a  balance  established  between  the  absorbing 
root  system  and  the  transpiring  leaf  system,  so  that  the  amount  of 
foliage  is  determined  accordingly.  If  the  amount  of  water  lost  by 
transpiration  exceeds  the  amount  absorbed  by  the  roots  the  plant 
usually  succumbs.  Happy  trees  are  those  in  which  the  amount  of 
water  available  exceeds  the  amount  transpired,  while  unhappy  trees 
are  suffering  physiologic  drought  through  the  action  of  the  wind  in 
moving  water  faster  than  it  can  be  supplied  (Figs.  114,  115,  116). 
Such  trees  are  seen  in  planted  specimens  in  Long  Island,  Nantucket 
and  along  our  seacoasts.  With  tornadic  winds,  trees  are  uprooted  in 
general  and  irreparable  damage  is  done. 

The  effect  of  lightning  is  a  marked  one,  as  a  determining  factor  in 
disease.  Recently  Jones  and  Gilbert^  have  published  a  paper  on  the 
lightning  injury  to  potato  and  cotton  plants.  One  case  occurred  in  a 
field  at  Monetta,  S.  C.  in  the  summer  of  1913.  The  cotton  plants 
were  fully  grown  and  after  a  severe  electric  storm  on  Aug.  3,  all  the 
cotton  plants  were  killed  over  an  area  three  rods  in  diameter.  The 
leaves  wilted,  died  and  blackened,  but  remained  attached  to  the  plants. 
The  most  pronounced  effect,  however,  was  on  the  stem  and  root  system. 
Other  cases  are  cited  of  a  similar  nature  in  Europe  and  America. 

The  action  of  lightning  on  trees  is  variable.  The  tree  may  be 
scorched,  it  may  be  stripped  of  its  leaves,  it  may  be  cleft  longitudinally, 
or,  more  rarely,  severed  horizontally.  Sometimes  the  bark  is  stripped 
from  only  one  side,  occasionally  without  a  trace  of  burning:  at  other 
times,  it  may  be  riddled,  as  by  worms,  with  a  multitude  of  Httle  holes. 
The  lightning  furrows  may  be  single,  double,  oblique  or  spiral.  If  the 
tree  is  inflammable  a  fire  may  be  started.  Such  tall  trees,  as  the  big 
trees  of  California,  have  been  struck  repeatedly  by  lightning  and  their 
leaders  broken  and  their  tops  stunted  as  a  consequence.  From  early 
times,  there  has  been  a  current  belief  that  certain  trees  attract  the  light- 
ning, that  others  are  not  struck.     The  elder  Pliny  beheved  that  "Light- 

^  Jones,  L.  R.  and  Gilbert,  W.  W.  :  Lightning  Injury  to  Potato  and  Cotton 
Plants.  Phytopathology,  5  :  94-101,  with  plate,  April,  1915;  Jones,  L.  R.:  Light- 
ning Injury  to  Kale.  Phytopathology,  7:  140-142  with  i  fig.,  Apr.,  1917;, 
Stone,  George  E.:  Electrical  Injuries  to  Trees.  Bull.  156,  Mass.  Agric.  Exper. 
Stat.,  Oct.,  1914. 


GENERAL   CONSIDERATION   OF   PLANT   DISEASES  289 

ning  never  strikes  the  laurel.''     In  certain  parts  of  the  United  States, 
it  is  held  that  the  beech  tree  is  never  struck. 

"Avoid  the  oak,  flee  from  the  spruce,  but  seek  the  beech,"  yet  in 
the  Garden  Magazine  for  January,  19 16,  is  given  a  photograph  and  an 
account  of  a  fine  beech  tree  which  was  struck  by  lightning  in  Pennsyl- 
vania about  the  middle  of  June.  Plummer^  sums  up  his  investigations 
on  the  relation  of  lightning  and  trees,  as  follows: 

1.  Trees  are  the  objects  most  often  struck  by  lightning  because: 
{a)  they  are  the  most  numerous  of  all  objects;  (b)  as  a  part  of  the  ground, 
they  extend  upward  and  shorten  the  distance  to  a  cloud;  (c)  their 
spreading  branches  in  the  air  and  spreading  roots  in  the  ground  present 
the  ideal  form  for  conducting  an  electrical  discharge  to  the  earth. 

2.  Any  kind  of  tree  is  likely  to  be  struck  by  lightning. 

3.  The  greatest  number  struck  in  any  locality  will  be  of  the  domin- 
ant species. 

4.  The  likehhood  of  a  tree  being  struck  by  lightning  is  increased: 
(a)  if  it  is  taller  than  surrounding  trees;  (b)  if  it  is  isolated;  (c)  if  it  is 
upon  high  ground;  (d)  if  it  is  well  (deeply)  rooted;  {e)  if  it  is  the  best 
conductor  at  the  moment  of  the  flash;  that  is,  if  temporary  conditions, 
such  as  being  wet  by  rain,  transform  it  for  the  time  from  a  poor  conduc- 
tor to  a  good  one. 

5.  Lightning  may  bring  about  a  forest  fire  by  igniting  the  tree  itself, 
or  the  humus  at  its  base.  Most  forest  fires  caused  by  Ughtning  proba- 
bly start  in  the  humus. 

Experiments  on  the  electric  conductivity  of  various  woods  shows 
that  this  conductivity  depends  upon  the  water  content  of  the  wood. 
When  absolutely  dry  none  of  the  specimens  showed  conductivity,  but 
the  resistance  of  all  was  practically  infinity. 

Effect  of  Smoke,  Soot,  Gases  and  Smelter  Fumes  on  Plants. — The 
smoke,  which  is  destructive  to  vegetation  under  our  modern  conditions, 
is  derived  from  four  sources  of  supply:  (i)  smoke  from  manufacturing 
plants,  or  from  large  buildings;  (2)  smoke  from  special  concerns,  such 
as  the  electric  power  plants  of  electric  trolley  lines;  (3)  smoke  from  rail- 
road locomotives;  (4)  smoke  from  the  chimneys  of  dwelling  houses. 
Smoke  belts  have  been  drawn  by  students  of  the  problem  to  determine 
the  area  influenced  by  the  smoke.     From  a  survey  made  for  the  City 

^Plummer,  Fred  G.:  Lightning  in   ReUition  to  Forest  Fires.     BulL  in,  U.  S- 
Forest  Service,  191 2. 
19 


290  GENERAL   PLANT   PATHOLOGY 

of  Des  Moines,  Iowa,  by  A.  L.  Bakke,^  it. has  been  found  that  conifers 
are  more  susceptible  than  deciduous  trees.  The  direct  injury  is  seen 
in  the  deposit  of  the  tarry  matters  of  the  smoke  in  the  stomata  of 
nearby  plants;  leaves  and  leaflets  are  shed,  or  assume  abnormal  shapes, 
and  the  formation  of  foodstuffs  is  hindered.  The  sulphur  dioxide  and 
acetylene  as  constituents  of  smoke  act  toxically  upon  the  plant.  The 
work  which  has  been  done  in  the  United  States  may  be  summed  up  as 
follows:  Burkhart  states  that  injury  from  gases  is  the  result  of  the 
chemical  constituent  of  the  smoke  and  is  not  due  to  the  clogging  of  the 
stomata.  The  investigation  of  J.  K.  Haywood^  in  the  vicinity  of 
the  famous  smelter  at  Anaconda,  Mont.,  is  of  importance.  He  finds 
that  trees  are  injured  at  a  considerable  distance;  that  very  small 
amounts  of  SO2  are  toxic  to  plant  growth;  that  water  used  for  irrigation 
purposes  often  has  sufficient  copper  in  it  to  be  toxic  to  plant  growth 
and  that  certain  trees,  as  the  juniper,  are  more  resistant  than  others.^ 
Officials  of  the  Forest  Service  are  watching  with  interest  the  develop- 
ments in  the  matter  of  the  fumes  from  copper  smelters  in  the  southern 
Appalachian  Mountains.  The  service  has  been  interested  for  years, 
but  since  the  acquirement  of  land  in  that  section  under  the  Weeks  law 
for  forestry  and  watershed  protection  purposes,  it  has  been  felt  that 
the  destruction  of  forests  by  the  action  of  the  fumes  should  be  stopped. 
W.  L.  Hall,  forest  supervisor  of  the  seventh  forest  district,  has 
recently  submitted  to  the  bureau  a  report  upon  the  subject.  It  seems 
that  one  or  more  of  the  purchase  areas  established  in  the  southern 
Appalachians  are  endangered  by  the  fumes,  which  are  of  a  sulphuric 
nature. 

iBakke,  a.  L.:  The  Effect  of  City  Smoke  on  Vegetation:  Bull.  145,  Agric. 
Exper.  Stat.  Iowa  State  Coll.  Agric.  &  Mech.  Arts.,  October,  1913;  The  Effect 
of  Smoke  and  Gases  on  Vegetation.  Proc.  Iowa  Acad.  Sci.,  xx:  169-187,  with 
bibliography;  also  Anderson,  Paul  J.:  The  Effect  of  Dust  from  Cement  Mills 
in  the  Setting  of  Fruit.     The  Plant  World,  17:  57-68,  March,  1914. 

2  Die  Beschadigung  der  Vegetation  durch  Rauch.  Handbuch  zur  Erkennung 
und  Beurteilung  von  Rauchschaden  von  Professor  Dr.  E.  Haselhofe,  Vorsteher 
der  landwirtschaftlichen  Versuchsstation  in  Marburg  i.  H.,  und  Professor  Dr.  G. 
LiNDAu,  Privatdozent  der  Botanik  und  Kustos  am  Kgl.  Botanischen  Garten  in 
Dahlem.     Mit  27  Textabb. 

3  Haywood,  J.  K.:  Bull.  89,  Bureau  of  Chem.,  U.  S.  Dept.  Agric,  1905;  In- 
jury to  Vegetation  and  Animal  Life  by  Smelter  Wastes.  Bull.  113  revised,  Bureau 
of  Chem.,  U.  S.  Dept.  Agric,  1910. 

''  The  Southern  Lumberman,  xxix:  27,  Nov.  6,  1915. 


GENERAL   CONSIDERATION   OF   PLANT   DISEASES  29T 

The  fumes  are  apt  to  destroy  any  vegetation  within  a  radius  of 
several  miles  of  the  southern  copper  smelters.  They  are  also  working 
destruction  in  the  forests  of  Montana,  California  and  other  states.  The 
action  of  the  fumes  is  peculiar  and  variable.  Some  trees  succumb 
quickly  to  their  deadly  effects,  notably  white  pine.  Other  trees  are 
more  resistant,  including  spruce,  it  is  said.  Nor  does  the  gas  act  uni- 
formly. Its  effects  vary  with  topographic  conditions.  The  fumes 
will  travel  long  distances  up  a  canyon  or  narrow  valley,  destroying  the 
woods  in  it,  but  leaving  trees  uninjured  on  either  side.  Again,  it  is 
said,  the  sulphur  fumes  collect  in  globular  form  something  like  soap 
bubbles,  and  drift  away,  doing  no  damage  until  the  globular  mass  dis- 
perses, sometimes  at  quite  a  distance.  To  a  greater  or  less  extent, 
forests  at  a  distance  of  several  miles  from  copper  smelters  may  be 
damaged  by  the  fumes. 

It  is  admitted  that  the  fumes  can  be  controlled  by  condensation  or 
consumption,  but  the  commercial  practicability  of  the  process  is  the 
pending  question.  The  fumes  can  be  and  are  to  a  certain  extent  con- 
verted into  sulphuric  acid,  but  the  smelter  people  claim  that  the  market 
for  this  product  is  Hmited,  and  that  it  does  not  pay  to  produce  more  than 
a  certain  quantity  of  it,  as  an  oversupply  sends  the  price  down,  which 
would  make  it  not  worth  while  to  control  the  fumes  further. 

Just  now  considerable  trouble  is  being  experienced  in  Tennessee 
and  Georgia  on  account  of  the  sulphur  fumes  from  copper  plants. 
In  1905  the  State  of  Georgia  took  action  against  these  companies, 
alleging  that  they  permitted  a  discharge  of  gases,  which  destroyed 
vegetation,  including  forest  trees,  in  that  state.  The  companies  were 
forced  to  install  plants  to  utiUze  a  considerable  percentage  of  the  sul- 
phuric acid  gas.  These  plants,  however,  have  been  unable  to  utilize 
a  sufficient  quantity  of  the  gas,  and  last  spring  the  supreme  court  de- 
cided to  have  a  special  expert  ascertain  the  amount  of  gas  released, 
and  the  amount  which  ought  to  be  utilized  in  order  to  make  the 
fumes  harmless. 

The  time  is  close  when  the  pathologist  will  have  to  take  up  this 
question  of  fume  damage,  since  large  sections  of  the  Cherokee  area  are 
subject  to  such  damage,  and  it  is  reported  that  the  injury  has  extended 
to  the  Georgia  area. 

The  injurious  effect  of  illuminating  gas  and  ethylene  upon  flowering 
carnations  has  been  investigated  by  Crocker  and  Knight.^     The  best 

1  Crocker  and  Knight:  Botanical  Gazette,  46:  256-276,  1906. 


292  GENERAL   PLANT   PATHOLOGY 

work  in  Italy  has  been  done  by  Brizi,in  England  by  Crowther  and  Rus- 
ton.^  Recently  in  America  J.  F.  Clevenger  has  published  a  bulletin 
(No.  7),  on  "Smoke  Investigation"  for  the  Mellon  Institute  of  Indus- 
trial Research  and  School  of  Specific  Industries,  University  of  Pitts- 
burgh, 19 1 3,  with  plates  showing  the  effect  of  the  smoke  on  the  struc- 
ture of  the  woody  specimens  examined  by  him. 

Illuminating  gas  absorbed  by  the  soil  from  nearby  gas  pipes  is 
injurious  to  trees  and  has  frequently  killed  them  outright,  as  instance 
a  group  of  street  trees  in  Merchantville,  N.  J.,  a  few  years  ago,  which 
were  killed  in  this  way,  and  for  which  the  owner,  Edwin  C.  Nevin, 
received  damages  from  the  gas  company  for  $1500,  as  a  result  of  a 
successful  lawsuit.  All  the  ordinary  gases  used  for  lighting  and 
heating  are  injurious  and  act  much  in  the  same  way.  Such  are  water 
gas,  coal  gas,  gasoline,  acetylene  and  others.  The  first  effects  of  gas 
poisoning,  may  be  seen  in  the  foliage.  The  leaves  turn  yellow  and  in 
some  cases  drop  off,  while  the  leaves  of  other  trees  fall  while  still  green. 
The  water  containing  the  gas  in  solution  passes  into  the  stem  and  the 
wood  and  the  cambial  portion  becomes  abnormal.  The  underlying 
tissues,  cortex,  bast  and  cambium  die.  Soon  various  species  of  fungi 
gain  access  to  the  tree  and  cause  its  decay.  With  the  Carolina  poplar 
especially,  the  bark,  cortex,  etc.,  on  the  trunk  towards  the  source  of 
absorption  showed  three  or  four  vertical  cracks,  or  lesions,  one-half  to 
two  and  a  half  feet  long.  The  bark  on  the  sides  of  these  cracks  bulged 
out  considerably,  and  an  investigation  showed  a  thix:k  layer  of  soft 
parenchymatous  tissue  extending  to  the  wood  and  derived  from  the 
cambium  zone.  Later  this  tissue  turned  brown,  disintegrated  and 
became  slimy  in  appearance,  the .  sUme  exuding  from  the  cracks. 
Illuminating  gas  dissolved  in  water  in  which  willow  cuttings  were  kept 
stimulated  the  opening  of  the  foliage  buds  several  days  earlier  than  plants 
grown  in  water  not  charged  with  the  gas.  Stone^  found  that  the  effect 
of  gas  on  lenticels  was  to  increase  their  size,  especially  under  water 
charged  with  the  gas.  This  appears  to  be  a  general  response  on  the 
part  of  the  plant  tissue  to  a  demand  for  oxygen. 

That  the  trees,  shrubs  and  flowering  plants  in  our  large  cities  and 

1  Journal  of  Agricultural  Science,  4:  25,  1911. 

2  Stone,  G.  E.:  Effects  of  Illuminating  Gas  on  Vegetation;  2sth  Annual  Rep. 
Mass.  Agric.  Exper.  Stat.,  January,  1913;  Shade  Trees,  Characteristics,  Adapta- 
tion, Diseases  and  Care.     Bull.  170,  Mass.  Agric.  Exper.  Stat.,  Sept.,  1916,  p.  220. 


GENERAL   CONSlDERyVTION    OF   PLANT   DISEASES  293 

in  the  country  along  our  trunk-line  railroads  are  subjected  to  conditions 
which  cause  unhealthy  growth  and  disease  has  been  proven  abundantly. 
Large  factories,  power  plants  and  railroad  locomotives  are  pouring  out 
volumes  of  smoke,  which  alone  is  highly  injurious,  but  in  addition  the 
acid  which  is  formed  in  the  combustion  of  coal,  when  dissolved  in  rain 
water,  has  injurious  effect  upon  fohage  and  other  plant  parts.  Its 
action  is  seen  in  the  corrosion  of  tin  roofs,  rain  pipes  and  ornamental 
iron  work  about  city  houses. 

The  following  note  is  of  interest  to  the  plant  pathologist  and  plant 
physiologist.^  During  the  night  of  Sept,  19,  1913,  a  light  rain  fell, 
followed  by  a  fine  drizzle  in  the  early  morning  of  Sept.  20.  The  wide- 
open  campanulate  flowers  of  the  common  morning  glory  (Ipomcea 
purpurea  Roth),  growing  on  a  lot  in  West  Philadelphia,  four  or  five 
blocks  from  the  Pennsylvania  Railroad,  had  their  usual  quota  of  rain- 
drops studded  over  the  upper,  inner  surface  of  the  purple  corollas. 
Wherever  the  drops  touched  the  surface  of  the  corolla,  the  purple 
color  was  changed  to  a  pinkish  red,  and  in  the  process  of  evaporation 
of  the  raindrops  the  acid  of  the  drops  was  concentrated,  so  that  after 
the  complete  disappearance  of  the  drops  a  brown  spot  was  left  in  the 
center  of  the  pinkish  red  circles  of  discoloration.  The  explanation  of 
the  alteration  of  color  is  found  in  the  change  of  the  sap  of  the  corolla 
cells,  where  touched  by  the  acid  raindrops,  from  an  alkaline  to  an  acid 
reaction.  A  similar  change  can  be  induced  in  blue  violet  petals  by 
bruising  them  slightly  and  placing  them  in  an  acid  liquid.  The  petals 
change,  hke  blue  alkahne  litmus  paper,  from  blue  to  red,  and  this  re- 
action with  violet  petals  has  proved  useful  in  the  physiologic  laboratory 
in  the  absence  of  litmus  paper.  In  nature  a  reverse  change,  which 
illustrates  the  same  chemic  principle,  takes  place  in  many  flowers  of 
plants  belonging  to  the  family  Boraginaceae.  For  example,  in 
Symphytum  and  Mertensia,  the  red  flower  buds,  the  cells  of  which  have 
an  acid  cell  sap,  gradually  change  to  blue  as  the  flowers  open.  That 
this  is  a  chemic  change  is  proved  by  treating  the  red  buds  with  an 
alkaline  fluid  and  the  blue  flowers  with  an  acid  one. 

Similar  spotting,  but  less  clearly  discernible  and  demonstrable,  as 
the  delicate  reaction  with  morning-glory  flowers,  undoubtedly  occurs 
on  leaves  and  fruits,  and  the  suggestion  is  made  here,  that  such  spots 

1  Harshberger,  John  W.  :  The  Acid  Spotting  of  Morning  Glories  by  City  Rain. 
Science,  new  ser.,  xxxviii:  548,  Oct.  17,  1913. 


294  GENERAL    PLANT    PATHOLOGY 

caused  by  the  acidity  of  raindrops  serve  repeatedly  as  the  points  of 
entry  of  parasitic  fungi,  for  there  are  many  leaf  spots  and  fruit  spots 
that  show  concentric  rings  of  diseased  tissue  in  the  earliest  lesions  pro- 
duced. A  fungus,  which  is  stimulated  to  growth  by  an  acid  condition 
of  the  cell  sap,  would  find  ideal  conditions  for  the  commencement  of 
growth  by  entering  areas  influenced  by  acid  raindrops. 

Traumatism. — Traumatism,  or  mechanic  injury,  may  be  of  various 
sorts  and  the  effects  are  dependent  upon  the  form  and  severity  of  the 
injury.  Mechanic  injury  to  the  plant  usually  takes  the  form  of  wounds, 
which  may  be  divided  into  natural  and  artificial.  Natural  wounds  are 
those  which  are  produced  on  plants  living  in  a  state  of  nature,  or  in  a 
cultivated  state  in  which  other  natural  agents  are  concerned  in  their 
production,  man's  activity  not  being  considered.  Insects  and  worms 
may  make  burrows  in  the  organs  of  plants.  For  example,  bark  boring 
is  accomplished  by  species  of  beetles,  so  also  are  tunnels  through  the  bark 
and  the  wood.  Pith  flecks  are  minute  brown  specks,  or  patches,  found 
in  the  wood  layers  of  trees.  They  consist  of  holes  formed  by  boring 
insects  filled  with  dead  parenchyma  cells,  or  dead  empty  cells  filled 
with  fungous  material.  Eroded  and  skeleton  leaves,  and  shot-holes 
in  the  leaf  tissue  are  directly  traceable  to  the  work  of  cutting  insects. 
Frost  cracks  are  longitudinal  wounds  produced  by  the  rending  action 
of  the  frost  on  the  bark  and  wood  of  the  trees.  Sometimes  this  takes 
place  with  a  loud  report.  The  attempt  on  the  part  of  the  plant  to 
heal  the  crack  generally  produces  a  frost  ridge.  Rents  made  by  light- 
ning also  occur.  Strangulations  are  lesions  formed  by  woody  vines,  by 
telegraph  wires,  or  the  like  pressing  on  the  outer  surface  of  stems  which 
grow  about  the  compressing  object  and  create  additional  pressure,  so 
that  the  compressed  tissue  dies.  Callus  forms  above  the  wounded 
areas  formed  by  compression.  Large  hailstones  sometimes  produce 
bruises  on  the  bark  of  young  trees,  as  also  the  bombs  shot  out  of  vol- 
canoes. The  abrasion  of  a  tree  by  the  branch  of  a  neighboring  tree 
rubbing  against  it  or  the  cutting  of  large  lateral  roots  in  laying  curb- 
stones must  be  classed  as  wound  phenomena.  Wounds  are  also 
formed  by  the  teeth  and  horns  of  various  mammals.  Rodents,  such 
as  mice,  rats,  beavers  and  squirrels,  are  responsible  for  wounds  pro- 
duced by  gnawing  with  their  chisel-shaped  incisors.  Bark  is  rubbed 
oft",  or  scratched  by  the  horns  and  antlers  of  animals  of  the  cow  and 
deer  tribes.     Wounds   are    formed  by   the  breaking  off  of  branches 


GENERAL    CONSIDERATION    OF    PLANT   DISEASES  295 

under  the  tearing  action  of  the  wind,  or  by  the  breaking  action  of  the 
weight  of  the  ice  and  the  snow  of  winter.  The  repair  of  wounds 
will  be  discussed  with  the  consideration  of  the  pathologic  anatomy 
of  plants,  which  will  form  a  separate  chapter  of  this  treatise. 

Artificial  wounds  are  due  to  the  influence  of  man.  The  ploughing, 
discing,  harrowing  and  cultivation  of  the  soil  frequently  abrade  roots, 
break  them  off,  or  seriously  wound  them.  Limbs  are  broken  off  and 
bark  removed  by  farm  implements.  Knife  and  axe  wounds  are  easily 
recognized  by  their  sharp  character,  where  the  cut  may  have  been 
made  vertically,  obliquely,  or  horizontally.  The  stripping  off  of 
pieces  of  bark  opens  up  the  inner  tissues  of  the  stem  to  the  attack  of 
the  agents  of  disintegration  and  decay.  The  removal  of  twigs  and 
branches  in  the  ordinary  operations  of  pruning  opens  up  wounds,  some- 
times of  a  gaping  character.  The  ringing,  girdling,  or  scarification 
of  trees  for  various  purposes,  if  not  properly  performed,  opens  up 
wounds,  so  do  nails,  or  spikes  driven  into  the  tree  for  various  purposes 
and  the  placing  of  electric  cables  and  telegraph  wires  along  our  streets 
and  roads  results  in  the  removal  of  tree  tops.  The  habit  of  cutting 
initial  letters  and  monograms  in  smooth-barked  trees,  such  as  the 
beech,  or  the  removal  of  sheets  of  birch  bark,  opens  up  wounds  of  vari- 
ous menace  to  the  health  of  the  tree.  Injuries  due  to  man-created 
environment  may  be  of  a  thousand  and  one  kinds  too  numerous  for 
even  a  brief  mention. 

Animate  Agents  of  Disease. — These  may  be  divided  into  two 
groups,  namely,  animal  and  plant.  Many  animals  are  responsible  for 
the  production  of  wounds  and  the  destruction  of  plant  parts.  Man, 
cattle,  herbivorous  animals,  rodents  (mice,  rats,  squirrels,  rabbits),  and 
birds  do  great  injury  to  plants  by  their  horns,  teeth,  claws  and  beaks 
(woodpeckers).  Among  the  invertebrates  are  to  be  included  the  in- 
sects, mites  and  worms.  Certain  nematode  worms  attack  the  roots  of 
a  large  variety  of  plants  and  produce  galls  of  characteristic  form  and 
appearance.  Phylloxera,  an  hemipterous  insect,  winters  on  the  roots 
of  the  grape,  mostly  as  a  young  wingless  form.  Wingless  individuals 
then  abandon  the  roots  and  crawl  up  the  stems  to  the  leaves,  where  they 
form  galls.  Formerly  introduced  into  Europe,  it  was  very  destructive 
to  European  grape  vines  until  it  was  found  that  it  could  be  controlled 
by  grafting  the  European  vine  on  the  roots  of  American  varieties. 
Insects  injurious  to  plants  may  be  roughly  divided  into  two  groups: 


296  GENERAL   PLANT   PATHOLOGY 

those  with  mandibulate,  or  bithig  mouth  parts,  and  those  with  hausti- 
late,  or  sucking  mouth  parts.  The  first  group  includes  the  insects 
that  bore  into  wood,  those  that  bite  off  the  leaf  surface  (Fig.  in)  and 
thus  skeletonize  leaves  and  those  which  tear  or  bite  pieces  out  of  leaves 
and  other  plant  parts  (Fig.  in).  The  sucking  insects  include  those 
like  the  bugs,  aphids,  or  plant  lice,  and  scale  insects  (Fig.  112),  which 
cannot  be  destroyed  by  stomach  poisons.  These  latter  insects  by  suck- 
ing the  plant  juices  do  irreparable  damage  to  all  kinds  of  fruit  and 
shade  trees,  and  reduce  materially  the  yield  of  agricultural  and 
horticultural  crops. 

Of  the  mites,  the  most  destructive  is  the  red  spider  Tetranychus 
niytilaspidis.  The  red  spider  is  probably  identic  with  the  insect 
known  throughout  Florida  as  the  Purple  Mite.  It  is  quite  a  small 
insect,  yet  distinctly  visible  to  the  naked  eye.  They  appear  during 
summer  in  great  numbers  and  damage  the  oranges  by  causing  the 
fruit  to  drop  and  injure  the  foliage  leaves  so  that  they  cannot  perform 
their  functions  properly.  The  leaves  become  spotted  and  lose  their 
glossy  green  color.  The  males  and  females  are  protected  by  stiff  hairs 
and  their  color  is  purplish,  or  reddish-purple  in  the  old  insects,  but  of  a 
lighter  red  when  young. 

Animal  galls  are  of  various  kinds.  Those  due  to  insects  are  charac- 
teristic and  will  be  described,  when  the  pathologic  anatomy  of  plants 
is  considered  in  detail. 

The  field  of  Economic  Entomology  is  a  special  one  and  there  are 
bulky  treatises  dealing  with  various  phases  of  it.  A  useful  book,  and 
written  in  an  easy  style  is  one  by  John  B.  Smith,  late  Entomologist  of 
the  New  Jersey  Agricultural  Experiment  Station,  and  is  entitled 
"Economic  Entomology  for  the  Farmer  and  Fruit  Grower."  etc. 
Although  published  in  1896,  it  is  still  a  useful  book.  A  few  American 
classics  on  the  subject  may  be  mentioned,  as  follows: 

Crosby,  C.  R.  and  Slingerland,  M.  V.:  Manual  of  Fruit  Insects, 

1915- 

Forbes,  S.  A.:  Several  Reports  of  the  State  Entomologist  on  the 
Noxious  and  Beneficial  Insects  of  the  State  of  Illinois. 

Harris,  T.  W.:  Insects  Injurious  to  Vegetation  (several  editions). 

Insect  Life,  seven  volumes  (a  mine  of  information  on  American 
economic  entomology). 

Packard,  Alpheus    S.:  Insects  Injurious    to  Forest    and  Shade 


GENERAL    CONSIDERATION    OF    PLANT    DISEASES  297 

Trees.  Fifth  Report  of  the  United  States  Entomological  Commission, 
1890. 

Riley,  C.  V.:  Several  Reports  on  the  Noxious,  Beneficial  and  other 
Insects  of  the  State  of  Missouri. 

Saunders,  Willi.^m:  Insects  Injurious  to  Fruits  (several  editions). 

United  States  Bureau  of  Entomology:  Popular  and  Technical 
Bulletins  on  Insects. 


CHAPTER  XXIV 

PLANTS  AS  DISEASE  PRODUCERS,  EPHIPHYTOTISM, 
PROPHYLAXIS 

Vegetal  Agents  of  Disease. — The  plants  which  are  known  to 
be  injurious  to  other  plants  fall  naturally  into  two  large  groups,  namely, 
the  Phanerogamic  and  the  Cryptogamic.  The  latter  includes  injurious 
algae,  slime  moulds,  bacteria  and  fungi. 

The  phanerogamic  parasites  belong  to  four  families  of  plants. 
Their  morphology  and  physiology  is  fairly  well  known,  so  that  in  their 
discussion,  we  are  entering  well-trodden  fields  of  investigation. 

The  flowering  plants,  which  lead  a  partially  or  wholly  dependent 
life  upon  a  host  plant,  may  be  considered  as  belonging  to  two  distinct 
groups:  the  green  parasites  and  the  chlorophylless  parasites.  The 
plants  of  the  first  group  illustrate  by  gradations  how  the  conditions  of 
life  of  the  second  group  have  arisen.  The  seeds  of  the  first  series  of 
green  parasites  begin  their  growth  in  the  soil  and  there  develop  into 
seedlings  with  cotyledons  and  root  system,  without  any  connection 
with  a  host  plant.  The  root  branches  supplied  with  suckers  then 
become  attached  to  the  roots  or  underground  stems  of  other  plants. 
About  one  hundred  plants  of  the  sandalwood  family,  Santalace^, 
belong  to  this  series,  including  the  true  sandalwood,  Santalum  album 
of  India,  where  its  roots  live  attached  to  the  roots  of  a  species  of  Acacia 
leucophcBa  and  Pride  of  India,  Melia  azidarachta^. 

The  bastard  toad-flax  of  Europe,  Thesium  alpinum,  is  another 
member  of  this  family.  It  develops  relatively  large  suckers,  which 
become  attached  to  the  roots  of  other  plants.  These  suckers  are  con- 
stricted near  their  point  of  insertion.  The  swollen  part  spreads  itself 
over  the  root  of  the  host  as  a  plastic  mass,  while  the  central  cores  per- 
forate the  root  and  grow  into  the  wood  of  the  host  where  they  spread 
out.     Comandra  umbellata  is  a  santalaceous  parasite  found  in  the  pine- 

"  Wilson,  C.  C:  Sandalwood.     Indian  Forester,  xli:  248,  August,  1915. 
298 


PLANTS    AS    DISEASE    PRODUCERS  299 

barren  region  of  New  Jersey.  The  family  Scrophulariace^  includes 
a  number  of  these  root  parasites.  Such  are  the  eyebright  {Euphra- 
sia), yellow-rattle  {Rhinanthus),  cow- wheat  (Melampyrum),  lousewort 
(Pedicularis)  and  others.  The  suckers  of  the  yellow-rattle  are  of 
considerable  size :  their  margins  are  swollen  and  they  spread  around  the 
roots  of  the  hosts.  Those  of  the  cow-wheat  resemble  in  general  those 
of  the  yellow-rattle.  In  America  species  of  Agalinis  (old  genus  Gerardia 
in  part)  are  known  to  have  parasitic  attachments  to  the  roots  of  various 
plants.  This  plant  is  a  member  of  the  family  Rhinanthacece  (Scroph- 
ULARiACE^,  tribe  Rhinanthae). 

The  second  series  comprises  the  chlorophylless  root  parasites,  such 
as  Lathrcea  squamaria,  the  toothwort.  The  young  seedling  lives  at 
first  upon  the  reserve  substances  of  its  seed,  sending  out  roots  in  all 
directions.  These  finally  fasten  to  the  roots  of  ash,  hornbeam  or 
poplar,  by  means  of  a  sticky  sucker,  which  develops  a  central  core 
that  penetrates  into  the  roots  of  its  host.  Colorless  shoots  covered 
with  whitish  scale  leaves  are  formed  and  the  flowering  shoot  which 
develops  above  ground  has  a  purphsh  hue. 

The  third  series  of  parasitic  flowering  plants  includes  those  of  the 
families  Orobanchace^,  Balanophorace^  and  Hydnorace^.  One 
genus,  Orobanche,  the  broom-rape  genus,  is  sufficiently  common  to  merit 
attention  (Fig.  117).  The  embryo  of  Orobanche  shows  no  trace  of  root 
and  stem  and  is  without  cotyledons.  It  is  a  spiral  filament  of  delicate 
cells  feeding  on  the  stored  reserve  food.  In  its  downward  growth,  its  tip 
traces  a  spiral  line  until  it  finds  the  roots  of  a  congenial  host,  when  it 
not  only  adheres  firmly  to  a  root,  but  swells  in  such  a  way  as  to  assume 
a  flask-shaped  appearance.  The  thickened  part  becomes  nodulated 
and  papillose  and  some  of  the  papillae  form  conic  pegs,  which  penetrate 
into  the  root  of  the  host  until  the  vessels  of  the  parasitic  attachment 
of  the  broom  rape  reach  the  vessels  of  the  host.  A  bud  is  formed  at 
the  point  of  union  between  host  and  parasite  and  a  strong  thick  flower- 
bearing  stem  grows  above  ground.  Closely  and  intimately  associated 
with  a  host,  such  as  a  clover  plant,  the  broom-rape  does  considerable 
damage.  Conopholis  americana  ,(Fig.  118)  and  C.  mexicana  live  as 
parasites  on  oak  roots,  developing  large  swelhngs  out  of  which  the 
flowering  shoots  grow. 

The  writer  collected  Conopholis  mexicana  in  1896  on  the  roots  of 
an  oak,  Quercus  reticulata,  on  the  mountains  at  Eslava  (10,000  feet) 


300 


GENERAL   PLANT   PATHOLOGY 


Fig.     117. — Broom-i-apu    (Orolnniche    minor)    upon    greenhouse    geranium. 
Halslcd,  B.  D..  Rep.  N.  J.  Agric.  Exper.  Slat.,  1905.) 


{After 


PLANTS   AS   DISEASE    PRODUCERS 


301 


above  the  Valley  of  Mexico.     Cf.  Wilson,  Lucy  L.  W.,  Observations 
on  Conopholis  americana.     Cont.  Bot.-Lab.,  Univ.  of  Pa.,  II:  3-19. 

The  fourth  series  of  phanerogamic  parasites  comprises  plants  of 
the  family  Rafflesiace^,  to  which  a  number  of  genera  belong.  Raf- 
Hesia  is  a  genus  confined  to  the  islands  off  southeastern  Asia,  Java, 
Borneo,  Sumatra  and  Philippines.     The  whole  plant  is  reduced  to  a 


Fig.   118. — Cancer-root,   Conopholis  americana  of  the  broom-rope  family,  Oroban- 
chea;  parasitic  on  roots  of  other  plants.     {From  Gager,  after  Elsie  M.  Kiltredge.) 


gigantic  ill-smeUing  flower,  one  meter  across,  with  parasitic  attach- 
ments suggesting  fungous  hyphae,  which  penetrate  the  roots  of  vines 
of  the  genus  Cissiis.  Brugmansia  and  Cytinus  are  two  other  genera 
of  this  family.  Cytinus  hypocistus  lives  on  the  roots  of  shrubs  of  the 
genus  Cistus  in  Mediterranean  Europe. 

The  fifth  series  of  parasitic  phanerogams  includes  epiphytes  of 
bushy  habit    belonging  to  the  family  Loranthace^.     The    genera 


302 


GENERAL   PLANT   PATHOLOGY 


Fig.  119. — Distorted  branch  of  mulberry  caused  by  mistletoe  {Phoradendron 
flavescens),  Austin,  Texas.  {After  York.  H.  H.,  Bull.  120.  Univ.  of  Tex.,  pi.  ix, 
March  15,  1909O 


PLANTS    AS    DISEASE    PRODUCERS  303 

Loranthns,  Phoradendron  and  Viscum  include  the  well-known  mistletoes. 
The  American  mistletoe,  Phoradendron  flavescens  (Fig.  119),  extends 
from  southern  New  Jersey,  Maryland,  Ohio,  Indiana  and  Missouri 
to  Texas.  It  is  a  slow-growing  green  parasite,  which  on  account  of  its 
chlorophyll  is  not  entirely  dependent  upon  its  host  for  its  carbohydrates 
(Figs.  1 20  and  121).  It  is  essentially  a  water  parasite,  and  consequently, 
its  parasitic  roots  or  sinkers  grow  into  the  woody  cylinder  of  its  host, 


Fig.  120. — Cross-section  of  a  live  oak  branch  showing  five  stems  of  mistletoe 
parasitic  upon  it.  Note  sinkers  on  parasitic  roots  penetrating  into  oakwood.  {From 
Gager.) 


where  they  spread  out  circumferentially  (Figs.  120  and  121).  The 
white  berries,  which  are  sticky,  are  carried  by  birds  as  the  sticky 
mass  containing  the  seeds  adheres  to  the  bill  and  is  only  removed 
by  rubbing  the  beak  against  the  bark  of  a  tree,  for  example. 
Mistletoe  does  not  kill  the  trees  directly,  but  it  often  causes  them  to 
become   very   much   dwarfed  and   their   branches   distorted   greatly. 


304 


GENERAL    PLANT    PATHOLOGY 


Parts  of  trees,  however,  may  be  killed.  ^  The  larch  mistletoe,  Razou- 
mofskya  Douglasii  laricis,  is  one  which  lives  on  the  western  larch  in 
Idaho  and  Oregon  and  in  the  open  places  interferes  seriously  with  the 
development  of  some  of  the  more  valuable  timber  trees. 

The  sixth  series  includes  the  climbing  parasites,  which  are  destitute 


Fig.  121. — Sectional  view,  partly  diagrammatic,  of  a  branch  infected  with 
mistletoe,  showing  relation  of  parasite  and  host,  a,  branch  of  host  tree;  b,  mistletoe; 
c,  primary  sucker;  d,  sucker  from  cortical  root;  e  f,  cortex;  g,  cambium;  h,  wood 
of  branch.     (After  Bray,  W.  L.,  Bull.  i66,  U.S.  Bureau  of  Plant  Industry,  Feb.  2,  1910.) 


1  The  student  should  consult  the  following  for  more  detailed  information  about 
mistletoe.  Sorauer,  Dr.  Paul:  Handbuch  der  Pflanzenkrankheiten  (2d  edition, 
1886,  ii:  25-32;  Peirce,  George  J.:  The  Dissemination  and  Germmationoi  Arceidho- 
lium  occidentalis.  Annals  of  Botany,  xix:99-ii3,  January,  1905;  York,  Harlan  H.: 
The  Anatomy  and  some  of  the  Biological  Aspects  of  the  American  Mistletoe. 
Bull.  Univ.  of  Texas,  Scientific  Series  13,  March  15, 1909;  Meinecke,  E.  P.:  Parasit- 
ism of  Phoradendron  juniperinum,  Proc.  Soc.  Amer.  Foresters,  vii:  35-41,  March, 
1912;  Mistletoe  Pest  in  the  Southwest,  Bull.  166,  Bureau  of  Plant  Industry; 
Weir,  James  R.:  Larch  Mistletoe,  do.  Bull.  317. 


PLANTS   AS    DISEASE    PRODUCERS 


305 


of  chlorophyll  and  whose  seeds  sprout  in  the  soil  and  send  up  a  filiform 
stem  which  brings  itself  by  its  movements  into  contact  with  some 
host  plant,  which  is  penetrated  by  parasitic  roots  which  enter,  as 
far  as  the  bast  region  and  extract  elaborated  food.  When  estabhshed 
on  the  host  the  parasite  severs  its  soil  connection.     Leaves-  have  been 


Fig.    122. — Dodder  (Cuscuta)  in  flower  and  parasitic  on  a  golden  rod,  Solidago  ultni- 
folia.      {From  Gager,  after  Elsie  M.  KlUredge.) 


reduced  to  a  few  scales  located  near  the  clusters  of  small  flowers  and  the 
twining  stem  assumes  a  yellow,  or  orange-yellow  color.  The  dodder, 
Cuscuta  (Figs.  122  and  123),  belonging  to  the  bindweed  family,  is 
illustrative  of  these  parasites. 

Related  in  habit  are  species  of  the  genus  Cassytha.  Most  of  the 
species  of  Cassytha  inhabit  Australia,  but  some  are  found  in  New 
Zealand,  Borneo,  Java,  Ceylon,  the  Philippines,  the  Moluccas,  South 


3o6 


GENERAL   PLANT   PATHOLOGY 


Africa,  the  West  Indies  and  Florida.  In  Florida/  Cassytha  filiformis 
is  abundant  on  the  dunes  and  in  the  rosemary  scrub,  where  it  spins  its 
yellow,  or  reddish-orange  stems  from  bush  to  bush. 

Fungous  Organisms  as  the  Cause  of  Disease.— The  first  part 
of  this  book  dealt  with  the  morphology,  physiology,  and  taxonomy,  of 


Fig.  123. — Photomicrograph  of  the  section  of  a  dicotyledonous  host  plant  para- 
sitized by  dodder,  Cuscula  sp.  At  D  and  Z>'  note  haustoria  entering  host  plant  as 
far  as  the  bast  region  of  the  stem.      (After  Gager). 


the  slime  moulds,  bacteria  and  true  fungi.     General  reference  was  made 
to  the  diseases  induced  by  them  and  in  the  third  part  will  be  given  an 

1  Harshberger,  John  W.  :  The  Vegetation  of  South  Florida.  Trans.  Wagner 
Free  Inst,  of  Science,  vii,  part  3,  October,  1914;  86;  Cf.  Boewig,  Harriet:  The 
Histology  and  Development  of  Cassytha  filiformis.  Cont.  Bot.  Lab.,  Univ.  of 
Penna.,  ii:  399-416,  1904. 


PLANTS   AS   DISEASE   PRODUCERS  307 

account  of  the  fungi  which  cause  specific  diseases.  It  remains  for  this 
discussion  to  consider  fungi  as  the  causes  of  diseases  in  general.  Fungi, 
using  the  word  in  the  broadest  sense  to  include  the  bacteria  and  slime 
moulds,  are  responsible  for  an  extraordinary  number  of  diseases.  The 
entrance  of  the  organism  into  another  is  known  as  infection.  Nothing 
like  the  infection  of  animals  where  the  microbe,  or  its  poison,  circulates 
in  the  blood,  and  finds  lodgment  in  most  of  the  organs  is  found  with 
plants.  Infection  follows,  when  a  fungous  spore  germinates  and  pro- 
duces an  infecting  hyphae,  which  grows  into  the  cells^  or  between  the 
cells  of  the  host,  it  may  be  reaching  to  the  ends  of  the  plant.  As  disease 
is  induced  by  parasitic  fungi,  the  parasite  which  enters  the  host  and 
spreads  through  it  must  absorb  and  utiHze  the  plastic  and  other  sub- 
stances of  the  plant,  which  is  parasitized.  Thus,  we  can  divide  the 
endophytic  hyphae  into  the  intercellular  hyphse  such  as  we  find  in  the 
oomycetous  fungi  and  Puccinia  simplex.  With  such  hyphae  ^he 
protoplasmic  and  other  contents  of  cells  are  utilized  by  the  formation 
of  haustoria  of  different  forms  and  kinds,  which  penetrate  the  interior 
of  the  cells.  The  second  kind  are  the  intracellular  hyphae,  which  as  in 
the  disease  of  the  plane  tree,  Gnomonia  veneta,  grow  lengthwise  and 
crosswise  from  cell  to  cell. 

The  growth  of  the  hyphae  between  and  through  the  host  cells  is 
accompanied  by  the  formation  of  soluble  ferments.  These  dissolve  the 
substance  of  the  cell  walls  of  cellulose,  or  woody  walls  with  lignin  and 
pigment  deposits.  The  hyphae  live  on  the  products  of  solution.^ 
Hence  timber  may  be  damaged  in  two  ways:  by  the  formation  of  minute 
pores  and  apertures  through  it ;  or  by  a  solution  of  the  cell- wall  materials. 
The  wood  loses  in  strength  and  in  weight  and  becomes  "rotten." 
This  rotten  condition,  however,  is  reached  in  a  multiplicity  of  ways,  for 
every  parasitic  fungus  that  lives  in  the  wood  of  growing  trees  destroys 
the  wood  in  a  manner  peculiar  to  itself.  Starch  grains  are  decomposed 
also  in  the  cells,  likewise  crystals  and  tannin,  for  by  the  disappearance 
of  the  latter,  the  smell  of  sound  wood  is  lost.  Hartig  has  described 
the  several  methods  in  his  ''Text-book  on  the  Diseases  of  Trees." 

Then  too,  we  have  the  epiphytic  fungi  which  live  on  the  surface 

^  Sometimes  the  h3^hae  grow  toward  and  surround  the  nucleus  as  the  nucleus 
exerts  a  chemotactic  influence.  Such  hyphae  may  be  termed  nucleotropic  as  in 
Puccinia  adoxce. 

^  Consult  Smith,  Erwin  F.:  Bacteria  in  Relation  to  Plant  Diseases,  ii:  76-89. 


3o8  GENERAL   PLANT   PATHOLOGY 

of  the  host,  as  with  the  common  mildews,  and  send  short  haustoria 
into  the  epidermal  cells  of  the  host  on  which  they  grow.  Some  fungi 
have  mycelial  hyphae  that  grow  in  both  ways,  intracellularly  and  inter- 
cellularly.  Others,  as  a  number  of  wood-destroying  fungi,  grow  down 
through  the  tissue  of  the  host  and  ultimately  kill  it.  Apical  growth 
is  shown  by  some.  The  haustoria,  as  they  enter  a  cell,  may  flatten  out 
against  the  cell  wall,  as  in  Piptocephalis.  Such  flattenings  are  known 
as  appressoria.  The  haustorium,  which  enters  a  cell,  may  become 
branched,  or  dendritic,  it  may  enlarge  into  a  haustorial  knob,  or  re- 
main as  an  haustorial  tube.  Internal  sclerotia  are  formed  sometimes 
in  certain  parasitic  fungi.  These  are  consolidated  or  hardened  masses 
of  hyphae,  which  are  associated  with  a  resting  period. 

Ordinarily  when  a  spore  falls  on  the  surface  of  the  plant,  it  produces 
a  germ  tube,  which  by  the  action  of  a  secreted  ferment  bores  its  way 
through  the  epidermal  cell  walls  and  thus  enters  the  host.  Sometimes 
it  penetrates  the  cuticle,  grows  between  it  and  the  cell  wall  and  grows 
down  between  the  membranes  of  the  cells,  as  in  Botrytis  parasitica. 
Occasionally,  but  not  commonly,  it  enters  through  the  stomata,  or 
sometimes  through  nectaries  and  stigmatic  surfaces.  However,  there 
are  certain  bacteria,  such  as  those  which  cause  the  black  rot  of  the 
cabbage,  which  fall  upon  the  drops  of  water  excreted  by  water  stomata 
and  by  following  the  water  back  into  the  plant  infect  the  cabbage 
leaves.  A  cork  layer  is  protection  against  infection.  Fungi,  however, 
gain  access  to  the  interior  of  the  plant  in  a  variety  of  ways.  Some 
years  ago^  the  writer  considered  the  way  in  which  fungi  enter  living 
trees  and  a  restatement  of  the  facts  presented  in  that  paper  is 
apropos. 

Occasionally  the  planted  seed  contains  a  dormant  fungus  (but  not 
as  a  mycoplasm  in  Eriksson's  sense),  which  begins  its  growth,  as  soon 
as  the  seedling  plant  emerges.  The  oat-  or  wheat-smut  spores  are 
produced  in  the  grain  and  consequently  infect  the  cereal  plant  when 
it  is  small,  and  at  or  near  the  surface  of  the  ground.  In  other  cases  the 
fungus  penetrates  the  underground  parts  or  the  twigs  of  trees.  Fungi 
gain  entrance  to  plants,  through  injuries  caused  by  mechanic,  meteoro- 
logic,  chemic,  or  other  agents.  Mechanic  injuries  are  due  to  man, 
animals,  or  other  causes,  such  as  the  weight  of  snow,  the  rubbing  of 

1  Harshberger,  John  W.:  How  Fungi  Gain  Entrance  to  Living  Trees.  Forest 
Leaves,  viii:  88-90,  December,  1901. 


PLANTS    AS    DISEASE    PKODUCERS 


309 


two  branches  together.  Squirrels  in  search  of  food  bite  off  the  twigs 
of  trees.  Deer  and  moose  browse  upon  the  tender  branches  and  bark 
of  various  trees,  the  moose  especially  upon  Acer  pennsylvanicum  and 
Sorbus  americana.  Grizzly  bears  rub  their  backs  against  the  bark  of 
trees  and  sometimes  in  this  way  decorticate  them.  Rodents  peel  off 
the  outer  protective  layers  of  roots  as  food,  or  as  material  with  which  to 
line  their  burrows.     The  mycelia  of  Rhizocionia,  or  the  oak-root  fungus. 


Fig.  124. — Street  tree  injured  by  use  as  a  hitching  post.      (  I//1 
Conn.  Agi-ic.  Expcr.  Stal.,  pi.  iii,  igou  ) 


\V.  C,  Rep. 


RoseUinia  quercina,  which  live  in  the  soil,  penetrate  into  roots  through 
wounds  produced  by  field  mice  and  gophers.  The  honey  agaric, 
Armillaria  niellea,  forms  strands  of  hyphae  known  as  rhizomorphs, 
which  grow  through  the  soil  and  find  an  easy  entrance  into  roots 
decorticated  by  rodents.  Beavers  are  active  agents  in  cutting  down 
trees  and  removing  the  bark  therefrom.  Woodpeckers  drill  holes  into 
trees  and  in  their  case  it  has  been  definitely  proved  that  they  carry  the 
viable  summer  spores  of   the  chestnut-bHgtht  fungus,  Endothio  para- 


3IO 


GENERAL   PLANT   PATHOLOGY 


sitica,  a  single  downy  woodpecker  carrying  757,074  spores.^  Wood- 
boring  insects  (Family  Scolytid^)  of  the  genera  Dendroctonus, 
Scolytus,  Tomicus  are  responsible  agents  in  the  destruction  of  trees 
opening  up  holes  through  which  fungi  may  gain  entrance.  Horses 
do  considerable  damage  to  trees  by  stripping  off  the  bark  with  their 
teeth,  and  street  trees  cannot  be  too 
soon  or  too  carefully  protected  from 
such  ravages,  for  a  tuHp  tree  planted  in 
the  afternoon  in  front  of  the  house  of 
the  writer  in  West  Philadelphia  had  a 
strip  of  its  bark  removed  by  the  curb- 
stone horse  of  a  delivery  wagon  before 
nightfall  of  the  same  day  (Fig.  124). 

Telegraph  wires  stretched  in  every 
direction  rub  against  the  trunks  and 
limbs  of  trees,  and  do  mechanic  injury 
in  this  way,  but,  if  the  insulation  is 
rubbed  off  the  tree  may  be  badly  burned, 
or  even  set  on  fire  by  the  electric  cur- 
rent, especially  on  rainy  days  when 
there  is  a  direct  grounding  of  the  cur- 
rent through  the  water  running  down 
the  crevices  of  the  bark.  Many  trees 
in  our  cities  are  planted  too  close  to  the 
curb  and  the  wheels  of  passing  wagons 
tear  off  pieces  of  bark  (Fig.  141). 
Farmers  in  plowing,  hoeing,  mowing 
and  cultivating  the  soil  injure  the 
roots  and  stems  of  cultivated  plants 
and  open  the  way  for  the  entrance  of  destructive  fungi.  The  blazing 
of  trees  by  surveyors,  the  careless  system  of  lumbering,  careless  trans- 
planting of  young  trees,  are  fruitful  sources  of  injury  to  trees.  Careless 
pruning  (Figs.  125  and  126)  of  trees  by  inexperienced  men,  such  as  was 
prevalent  in  Philadelphia  before  the  Park  Commission  undertook  to 
properly  care  for  the  trees,  caused  the  death  of  many  fine  shade  trees. 


Fig.  125. — Decay  following  un- 
skillful pruning.  {Slurgis,  W.  C. 
Rep.  Conn.  Agric.  Ex  per.  Stat.,  pi 
Hi,  1900.) 


1  Heald,  F.  D.  and  Studhalter,  R.  A.:  Preliminary  Note  on  Birds  as  Carriers 
of  the  Chestnut  Blight  Fungus.     Science,  new  ser.,  xxxviii:  278-280,  Aug.  22,  1913. 


PLANTS   AS   DISEASE   PRODUCERS 


311 


Stubs  were  left  which  never  healed  over  and  through  the  exposed  sur- 
face the  fungi  of  wood  decay  gained  easy  access. 

The  injuries  produced  by  meteorologic  causes  are  important. 
Entire  forests  have  been  levelled  by  tornadoes.  Cracks  are  produced 
by  wind  action.  Lightning  opens  a  way  by  cracks  to  the  interior. 
Snow  and  ice  snap  off  large  limbs  and  hail  stones  bruise  the  bark  and 
leaves  of  trees  so  that  fungi  can  readily  enter.  Chemic  substances  are 
rather  exceptional  destructive  agents  to  which  reference  has  been  called 


26. — Black  walnut,  Juglans  nigra.      Cold  Spring  Harbor,  L.    I.      Note  large 
open-branch  stub  (July,  1914). 


in  a  previous  page.  Besides  these  agents,  it  occasionally  happens,  that 
fungi  enter  healthy  plants  through  diseased  grafts  which  are  inserted. 
Robert  Hartig  mentions  such  a  graft  union  of  diseased  and  healthy 
roots  in  the  case  of  the  red-rot  fungus,  Trameies  radiciperda.  Here 
contact  of  the  diseased  root  containing  the  fungus  with  the  sound  one 
of  a  neighboring  tree  and  the  partial  natural  graft  union  of  these  two 
roots  explains  how  such  infection  occurs.  An  enumeration  of  the 
way  in  which  fungi  can  gain  entrance  to  plants  follows: 


312 


GENERAL   PLANT   PATHOLOGY 


Infection   by  natural 
growth  of  the  fungus 


A.  By  means  of  spores,  or  h>i)luc,  into  stoinata  and 
water  stomata. 

B.  By  rerment  action  of  a  fungus  on  the  epidermis  of 
the  host. 

f  By  developing  from  a  dormant  state  in  the  seed  into 
[  an  active  state  in  the  seedling. 

[  Beasts 
I.  Mechanic  injuries  )  Man 


Infection  through 


induced  by 


II.   Meteorologic  in- 
juries induced  by 


III.  Chemic  injuries 
induced  by 


Fall  of  fruit 

Combined  weight  action  of  fruit 

Wind 

Snow 

Ice 

Hail 

Lightning 

Sun 

Frost 

Factory  gases 

Sewer  gases 

Locomotive  gases 

Chemicals  at  roots. 

Alkali  soils 

Gases  and  chemicals  in  geysers,  etc. 


IV.    Non-classifiable 
injuries  induced  by 


Natural  grafting  and  budding 


Incubation.^ — The  period  of  incubation  is  the  time  between  ex- 
posure to  the  cause  of  the  disease  and  the  first  appearance  of  the  symp- 
toms, or  physical  signs  of  the  disease.  This  period  in  plants  is  quite  as 
variable  as  in  animals,  and  it  is  dependent  on  the  nature  of  the  organ- 
ism, whether  it  is  virulent,  or  its  virulency  attenuated,  on  its  food  re- 
quirements, on  its  temperature  requirements,  the  volume  of  infectious 
material,  the  stage  of  development,  or  age  of  the  host  plant,  the  amount 
of  water  and  air  in  the  invaded  tissues,  and  individual  or  varietal  re- 
sistance. The  period  of  incubation  may  be  as  short  as  a  few  hours, 
or  as  long  as  three  to  four  weeks.  Presumably  on  seedling  tissues  the 
period  of  incubation  of  the  damping-off  fungus,  Pythium  de  Baryanum, 
is  only  a  few  hours.  Experiments  performed  by  Erwin  F.  Smith^ 
1  Smith,  Erwin  F.:  Bacteria  in  Relation  to  Plant  Diseases,  ii:  66. 


PLANTS   AS    DISEASE    PRODUCERS 


313 


with  Bacillus  trachciphUus  and  young  cucumbers  where  the  organ- 
ism was  inoculated  from  young  cultures,  and  on  susceptible  plants  by 
needle-pricks,  showed  that  signs  of  disease  rarely  appeared  in  less  than 
three  to  four  days,  and  that  signs  of  wilt  and  change  of  color  usually 
were  visible  in  five  to  seven  days.  In  the  case  of  the  white  pine  bhster 
rust,  Cronartium  ribicola,  the  period  of  incubation  in  the  pine  is  from 
one  to  six  years. 

Duration  of  Disease. — The  resistance  of  plants  to  disease  is  various 
even  after  the  fungus  has  obtained  an  entrance  into  the  tissue  of  the 


Fig.    127. — Chestnut,  Caslanea  denlaia,  killed  by  blight  fungus,  lindolhia  payascaili, 
Cold  Spriiig  Harbor,  L.  I.,  July,  1914. 

host.  In  the  case  of  large  trees  like  the  white  oak,  a  number  of  years 
may  elapse  before  the  tree  finally  succumbs  to  such  fungi,  as  Fomes 
{Poly poms)  applanatus.  A  chestnut  tree,  a  few  miles  outside  of 
Philadelphia  resisted  the  chestnut-blight  disease  for  over  four  years 
from  the  time  of  first  infection  before  it  finally  succumbed.  Smith 
{loc.  cit.)  describes  how  a  good-sized  potato  tuber  was  half  rotted  in 
five  days  at  ordinary  autumn  temperatures  when  inoculated  with 
Bacillus  phytophthorus  by  means  of  a  few  needle-pricks. 


314  GENERAL   PLANT   PATHOLOGY 

The  final  outcome  of  the  disease  may  be  a  complete  destruction  of 
the  host  (Fig.  127),  or  its  complete  recovery.  The  simplest  cases  are  leaf 
spots,  or  fruit  spots,  which  are  removed  from  the  plant  when  the  leaves 
and  fruits  fall  without  in  any  way  jeopardizing  the  general  health  of  the 
plant.  Sometimes  the  plant  recovers  from  bacterial,  or  fungal  diseases, 
but  such  recovery  does  not  protect  the  plant  from  subsequent  attacks 
of  the  same  disease,  as  is  the  case  with  some  diseases  of  animals.  Old 
and  slow-growing  cabbages  are  rather  resistant  to  Pseudomonas  cam- 
pestris  while  young  and  rapidly  growing  plants  are  apt  to  be  destroyed. 
Vaccination  of  plants  to  ward  off  diseases  has  never  been  successful, 
and  it  is  doubtful  whether  this  means  of  protection  is  available  for 
plants.  It  is,  however,  a  wholly  unworked  field.  Some  experiments 
which  Smith,  Townsend  and  Brown  performed  in  1908  and  1909  seem 
to  show  that  after  Paris  daisies  have  been  inoculated  several  times  with 
Pseudomonas  tumefaciens  with  the  production  of  tumors,  that  subse- 
quent inoculations  with  cultures  of  the  same  virulence  are  without 
effect,  but  owing  to  the  possibility  that  the  results  were  due  to  loss  of 
virulence,  the  experiments  were  inconclusive.  For  the  student,  who 
may  be  interested  in  pursuing  this  line  of  important  research  work 
further,  the  following  bibliography  is  here  given,  taken  from  Smith. 

Shattock,  Samuel  G.:  The  Healing  of  Incisions  in  Vegetable  Tissues.     Journ. 

Path,  and  Bact.     Edinburgh  and  London,  v:  39-58,  1898. 
HiLTNER,  L.  and    Stormer,  K.:  Neue  Untersuchungen  iiber  die  WurzelknoUchen 

der  Legurainosen   und  deren  Erreger.  Arb.  a.d.  Biologischen  Abt.  fur  Land- 

und  Forstwirthschaft  am  Kaiser.     Gesundheitsamte  iii,  heft  3:  151,  1903. 
Brullowa,  J.  P.:  Ueber  den  Selbstschutz  der    Pflanzenzelle  gegen  Pilzinfektion. 

Jahrb.  f.  Pflz.  Krh.     K.  Bot.  Garten  Petersb.,  Nr.  4,  1907. 
Alten,    H.   von:     Zur     Thyllenfrage.     Callusartige    Wucherungen    in    verlezten 

Blattstielen  von  Nuphar  luteum.     Bot.  Ztg.,  68,  part  ii:  89-95,  1910. 
Smith,  Erwin  F.:  Bacteria  in  Relation  to  Plant  Diseases,  ii:  93-94,  1914. 

DISSEMINATION  OF  FUNGI 

Fungi  are  usually  reproduced  by  spores,  which  are  minute  and  light 
and  easily  carried  about  by  various  agents,  such  as  on  seeds,  by  the  wind, 
by  water,  by  insects,  by  other  animals,  by  agricultural  and  commer- 
cial practices  and  by  railroads,  cars  and  other  vehicles.  The  black-leg, 
or  Phoma  wilt  of  cabbage  of  recent  introduction,  was  introduced  from 
Europe  undoubtedly  with  imported  seed,  and  as  we  have  seen  various 


PLANTS   AS   DISEASE   PRODUCERS  315 

smuts  are  carried  by  the  single  fruits  of  various  grains.  In  the  aecial 
stage  of  the  cedar-apple  fungus,  Gymno sporangium  juniperi-virginiance, 
the  spores  are  set  free  during  dry  weather  at  a  time  when  they  are  most 
likely  to  be  wind-carried.^  The  spores  of  the  water  molds  are  carried 
by  currents  of  water  and  those  of  the  cranberry  gall  due  to  Synchy- 
trium  vaccinii.  The  motile  zoospores  of  the  damping-off  fungus  need 
water  for  their  dissemination.  The  spores  developed  during  the 
Sphacelia  stage  of  the  ergot  fungus  on  rye  are  carried  by  insects.  The 
formation  of  the  conidiospores  is  accompanied  by  a  sweet  substance, 
the  so-called  honey-dew,  which  is  much  relished.  Birds,  especially 
woodpeckers,  disseminate  the  spores  of  the  chestnut-blight  fungus, 
Endothia  parasitica,  and  in  a  great  many  different  ways  man  is  active. 

EPIPHYTOTISMS  (EPIDEMICS) 

When  a  plant  disease  becomes  virulent,  rampant  and  aggressive, 
spreading  rapidly  from  place  to  place,  it  is  said  to  be  epiphytotic 
(epidemic).  A  number  of  such  epiphytotisms  (epidemics)  have  oc- 
curred and  the  destruction  due  to  some  particular  plant  disease  has 
been  enormous.  The  potato  crop  in  the  British  Isles  during  the 
summer  of  1845,  owing  to  a  high  temperature  and  abundant  rains, 
suffered  entire  destruction  in  the  short  space  of  a  fortnight.  This  was 
due  to  the  ravages  of  Phytophthora  infestans,  an  oomycetous  fungus, 
whose  spores  in  wet  weather  produce  numerous  infecting  motile 
zoospores.  The  destruction  of  the  potato  crop  led  to  the  repeal  of  the 
corn  laws  of  England,  and  as  a  sequence,  the  inauguration  of  a  free  trade 
policy.  The  Irish  famine  was  the  direct  result  and  thousands  of  the 
natives  of  the  Emerald  Isle  emigrated  to  America.  With  respect  to  the 
disease  known  as  peach  yellows  Dr.  Erwin  E.  Smith  writing  in  1891^ 
says:  "Formerly  this  disease  was  confined  to  a  small  district  on  the  At- 
lantic Coast,  but  during  the  last  twenty  years  it  has  invaded  distant 
regions  hitherto  free,  and  has  entirely  ruined  the  peach  industry  over 
very  considerable  areas.     Within  ten  years  the  disease  has  taken  fresh 

1  Heald,  V.  D.:  The  Disseminations  of  Fungi  Causing  Disease.  Trans. 
American  Microscopical  Society,  xxxiii:  5-29,  June,  1913. 

2  Smith,  Erwin  F.  :  Additional  Evidence  on  the  Communicability  of  Peach 
Yellows  and  Peach  Rosette,  Bull,  i,  Div.  of  Vegetable  Pathology,  U.  S.  Dept. 
Agric,  1891. 


3l6  GENERAL   PLANT   PATHOLOGY 

very  strong  hold  upon  the  orchards  in  the  Delaware  and  Chesapeake  and 
region,  the  north  portion  of  the  peninsula,  and  has  destroyed  thousands 
and  thousands  of  trees,  rendering  a  great  industry  unprofitable  and 
precarious."  The  recent  spread  and  virulency  of  the  chestnut-blight 
fungus,  Endothia  parasitica,  from  the  neighborhood  of  New  York  City, 
where  it  was  probably  first  introduced,  is  so  recent  and  fresh  in  the 
minds  of  the  public,  that  an  extended  account  of  the  epiphytotism 
(epidemic)  need  hardly  be  made  here.  The  disease  has  practically 
destroyed  the  native  chestnut  trees  of  the  forested  areas  of  the  east- 
ern states  east  of  a  line  running  northeast  and  southwest  through 
the  central  part  of  Pennsylvania .  There  have  been  a  few  sporadic  cases 
west  of  that  line  removed  through  the  heroic  efforts  of  the  men  em- 
ployed by  the  Pennsylvania  Chestnut  Blight  Commission,  who  with  a 
big  appropriation  of  state  money  tried  to  find  a  way  of  heading  off  the 
disease  and  finally  controlling  it  but  without  success.  Introduced  in  all 
probability  from  China,  where  it  has  been  found  recently,  the  ravages 
of  this  disease  have  been  without  precedent. 

As  to  the  epiphytotic  diseases  of  plants  due  to  animals,  we  have  a 
number  of  instructive  illustrations.  The  account  of  the  introduction, 
spread  and  final  control  of  the  cottony  cushion  scale  forms  one  of  the 
most  interesting  chapters  in  the  history  of  American  phytopathology. 
Having  been  introduced  from  Australia  to  California  in  1868,  it 
spread  so  rapidly  during  the  next  twenty  years  that  its  ravages  proved 
a  very  serious  menace  to  the  citrus  industry  of  the  southern  part  of 
California.  The  Australian  ladybird  beetle,  which  was  introduced 
into  California  from  Australia  in  1889  for  the  purpose  of  controlling 
this  scale,  was  so  successful,  that  except  for  occasional  outbreaks  it 
ceased  to  be  considered  a  serious  citrus  pest. 

All  of  these  epiphytotisms  (epidemics)  and  others  that  might  be 
cited  have  been  possible  in  all  probability  because  the  climatic  condi- 
tions of  temperature,  moisture,  rainfall,  wind  and  soil  conditions  have 
been  favorable  during  the  period  of  most  active  virulency,  when  the 
diseases  became  firmly  established.  As  an  important  contributing 
cause  may  be  considered  the  unhealthy,  abnormal,  or  susceptible  condi- 
tion of  the  host  plant  owing  to  the  methods  of  cultivation  which  have 
reduced  the  disease-resisting  capacity  of  the  plant.  In  the  case  of 
the  chestnut,  the  restoration  of  the  trees  by  sprouting  from  the  stump 
was  undoubtedly  one  of  the  contributing  causes  of  the  rapid  spread  of 


PLANTS   AS   DISEASE    PRODUCERS  317 

the  disease.  Altogether,  these  epiphytotisms  (epidemics)  result  either 
when  the  conditions  are  favorable  for  the  spread  of  the  parasites,  or 
when  the  general  tone  and  health  of  the  plant  has  been  lowered  by 
improper  methods  of  handling,  so  that  its  disease-resisting  capacity 
has  been  reduced.  Recognizing  the  possibility  of  the  introduction  of 
other  virulent  fungous,  or  animal  diseases,  a  stricter  quarantine  has 
been  instituted  by  both  the  individual  state  and  national  governments 
with  a  careful  inspection  of  nursery  stock  designed  for  shipment  from 
place  to  place. 

PROPHYLAXIS 

Prophylaxis  may  be  defined  as  the  means  taken  to  prevent  disease. 
It  includes  a  consideration  of  the  methods  of  protecting  plants  from 
disease,  of  preventing  the  spread  of  disease,  and  of  the  methods  of 
breeding  by  which  the  disease  resistance  of  plants  is  increased  until  in 
some  cases  absolute  immunity  is  reached  and  the  plant  is  made  proof 
against  disease.  Some  diseases  are  preventible  by  the  observance  of 
proper  care  in  the  cultivation  of  plants,^  and  by  habits  of  cleanliness, 
when  no  refuse  which  might  harbor  insect  or  fungous  disease  is  per- 
mitted to  remain,  but  is  either  destroyed,  or  rendered  innocuous. 
For  example,  vegetable  and  agricultural  crops  should  be  rotated,  so 
that  the  same  crop  would  not  follow  upon  the  same  piece  of  soil  where 
the  animal  or  fungous  parasite  may  be  lurking.  Neither  should  the 
farmer  attempt  to  cultivate  certain  crops  in  acid  soils,  or  in  low  situa- 
tions subject  to  frost  action.  Nor  should  seeds  be  placed  in  beds  rife 
with  the  spores  of  the  damping-off  fungus,  Pythium  de  Baryamim.  By 
proper  care  on  the  part  of  the  grower  diseased  plants  should  not  be 
sent  away  from  an  infected  locality,  and  vice  versa,  he  should  be  careful 
about  the  introduction  of  nursery  stock  and  plants  from  other  localities 
without  a  careful  inspection.  The  national  and  state  quarantine 
regulations  are  designed  to  help  the  grower  in  these  respects,  and  he  can 
refuse  to  purchase  new  plants  without  they  are  accompanied  by  a 
certificate  setting  forth  that  these  plants  are  free  from  animal  and 
fungous  diseases.     Orton-  in   two  suggestive  papers,  has  shown  that 

^  BoLLEY,  H.  L. :  Cereal  Cropping:  Sanitation,  a  New  Basis  for  Crop  Rotation, 
Manuring  Tillage  and  Seed  Selection.     Science,  xxxvii:  249-250,  Aug.  22,  1913. 

^ Orton,  W.  A.:  International  Phytopathology  and  Quarantine  Regulation, 
Phytopathology,  3:  143-151,  June,  1913.  The  Biological  Basis  of  International 
Phytopathology,  Phytopathology,  3:  325-333,  February,  1914. 


3l8  GENERAL   PLANT   PATHOLOGY 

this  problem  is  not  only  of  national,  but  of  international  and  inter- 
continental importance.  These  papers  should  be  read  by  every 
serious-minded  student. 

Plant  protection  may  be  secured  by  the  use  of  spraying  materials.^ 
The  principal  rules  to  be  observed  in  their  use  are:  (i)  the  poison  em- 
ployed must  be  sufficiently  strong  or  concentrated  to  kill  the  parasite, 
but  not  sufficiently  powerful  to  injure  the  host;  (2)  it  must  be  applied  at 
the  right  time,  as  suggested  by  a  knowledge  of  the  life  history  of  the 
fungus,  or  insect  in  question.  Such  sprays  may,  therefore,  be  divided 
into  two  kinds,  viz.,  insecticides  and  fungicides.  Applications  of  these 
to  healthy  plants  serve  to  protect  the  plant  from  the  attacks  of  its 
fungous  and  insect  enemies.  Vast  possibilities  of  controlling  disease 
have  been  opened  up  by  the  treatment  of  seeds  with  hot  water  and  other 
substances  before  the  seeds  are  planted. 

iMcCuE,  C.  A.:  Plant  Protection.  Bull.  97,  Del.  Coll.  Agric.  Exper.  Stat. 
June  IS,  1912;  Rees,  Charles  C.  and  Macfarlane,  Wallace:  A  Bibliography  of 
Recent  Literature  Concerning  Plant  Disease  Prevention.  Univ.  of  111.:  Agric. 
Exper.  Stat.,  Circular  183,  May,  1915. 


CHAPTER  XXV 
PRACTICAL  TREE  SURGERY^ 

The  object  of  tree  surgery  is  to  repair  the  damage  done  to  trees  by 
the  various  causes  previously  described  (page  274).  The  principles 
involved  in  all  such  remedial  work  are  the  removal  of  all  decayed,  dis- 
eased, or  injured  wood  and  bark,  the  cauterization,  sterilization,  and 
waterproofing  of  the  cleaned,  or  cut,  surfaces,  and  the  putting  of  the 
tree  in  a  condition  for  rapid  healing.  Such  treatment  should  be 
watched  from  year  to  year,  so  that  any  defects  will  receive  immediate 
attention. 

As  the  work  requires  the  apphcation  of  scientific  principles,  no 
ignorant  laborers  should  be  employed.  The  men  who  act  as  tree  sur- 
geons should  have  some  knowledge  of  the  structure  of  trees,  their 
physiology  and  their  habits  of  growth.  A  knowledge  of  the  general 
principles  of  horticultural  practice  would  not  come  in  amiss,  such  as 
the  tenets  of  grafting  and  pruning.  Such  workmen  would  be  still 
better  prepared,  if  acquainted  with  the  structure,  growth  and  life 
histories  of  the  common  destructive  fungi  and  insects.  If  a  town  or 
municipality  is  unable  to  obtain  such  skilled  labor,  then  the  appoint- 
ment of  a  superintendent,  or  town  forester,  who  is  acquainted  with  such 
matters,  should  be  made.  Such  a  man  should  know  the  right  thing 
to  be  done  and  all  the  details  of  the  work. 

Preventive  Measures. — As  means  Oi"  preventing  injuries  to  trees, 
various  things  may  be  done.  The  placing  of  an  open  tree  box  or  fence 
of  iron,  or  wire  netting,  is  important,  because  it  protects  the  tree  from 
the  gnawing  of  horses  and  the  rubbing  action  of  passing  vehicles,  or  the 
viciousness  of  street  arabs.  Proper  attention  to  the  insulation  of 
telephone,  telegraph  and  electric  wires  will  prevent  a  lot  of  damage  to 
shade  trees.     Electric  linemen,  unless  properly  supervised,  have  no 

'  A  detailed  account  of  practical  tree  surgery  by  J.  Franklin  Collins  will  be  found 
in  the  Yearbook  of  the  United  States  Department  of  Agriculture,  1913;  also  con- 
sult Stone,  George  E.:  Shade  Trees,  Characteristics,  Adaptation,  Diseases  and 
Cure,  Bull.  170  Mass.  Agric.  Exper.  Stat.,  Sept.,  191 6. 

319 


320 


GENERAL   PLANT   PATHOLOGY 


regard  for  shade  trees,  as  they  look  upon  them  as  obstacles  to  the 
prosecution  of  their  work.     Improper  pruning,  when  large  stubs  are 


Jl 

IFI 

^ 

Ci 

"    '-"^4 

/'^ 

^^E 

r^  m 

^Hy 

^    '  m 

^^1 

M 

md 

f 

Fig.  128. — Properly  treated  area  left 
by  branch  removal.  Scar  beginning  to 
heal  over  by  callus  growth.  (After 
Collins,  F.  L.,  U.  S.  Yearbook  Dept. 
Agric,  1913-) 


Fig.  129. — Properly  treatcil  branch 
scar'  about  three-quarters  healed  over. 
(After  Collins,  F.  L.,  Yearbook  U.  S. 
Dept.  Agric,  1913) 


left,  is  another  source  of  danger  to  the  tree,  which  with  proper  knowledge 

can    be    safeguarded.     There    are    a 

thousand  and  one  details  which,  if 
neglected,  will  work  injury  to  the 
planted  trees. 

Character  of  the  Work. — Tree  sur- 
gery consists  in  the  removal  of  de- 
cayed or  dead  limbs  from  trees,  the 
cutting  ofif  of  stubs  left  by  improper 
methods  of  pruning,  and  the  treat- 
ment of  scars,  holes  and  cavities,  so  as 
to  prevent  decay  and  secure  proper 
healing  (Figs.  128,  129,  130).  The 
removal  of  branches  from  trees  should 
be  done  in  such  a  way  as  to  prevent 
injury  to  the  surrounding  bark  and 
cambium  or  active  layer  of  growth. 
For  this  purpose,  a  saw,  or  gouge,  a  chisel,  a  mallet  and  a  strong 
knife  are  essential.     Where  the  branches  are  high  above  the  ground, 


Fig.  130. — Cross-section  of  7- 
year  old  blaze  on  a  quaking  aspen 
nearly  healed  over.  (After  Collins, 
F.  L.,  Yearbook  U.  S.  Dept.  Agric. 
1913-) 


PRACTICAL  TREE  SURGERY  32 1 

a  rope  and  ladder  are  needed.  The  cuts  should  be  made  close  to  the 
main  tree  trunk,  so  as  to  reduce  the  surface  exposed  to  the  action  of 
the  elements.  Cut  surfaces  should  be  cauterized  and  water-proofed. 
The  best  antiseptic  dressings  are  some  of  the  creosotes,  which  destroy 
and  prevent  the  growth  of  wood-destroying  fungi,  because  it  penetrates 
the  wood  better  than  a  watery  antiseptic.  The  antiseptic  treatment 
with  creosote  should  be  followed  by  painting  the  scar  with  coal-tar. 
Lead  paint  is  sometimes  more  available.  It  is  useful,  but  not  as 
satisfactory,  as  a  heavy  coat  of  coal-tar. 

Cavity  Treatment. — The  removal  of  all  decayed  and  diseased  parts 
of  the  tree  should  be  accomplished  first  by  the  use  of  gouges,  chisels  and 
scraping  tools.  The  use  of  the  chisels  is  assisted  by  a  wooden  mallet. 
These  cutting  instruments  should  have  keen  edges  for  the  cambium 
may  be  injured  by  dull  tools.  After  properly  clearing  away  all  decayed 
material,  the  freshly  cut  surfaces  should  be  treated  with  creosote  and 
heavy  coal-tar  which  should  coat  the  surface  of  the  sound  and  healthy 
exposed  surfaces  of  the  wood.  The  excavation  should  be  so  made  as 
to  provide  drainage  at  the  bottom  of  the  cavity,  but  the  undercutting 
should  be  done  in  such  a  way  as  to  hold  the  filling  material.  Before 
the  filling  material  is  added  to  the  cavity,  it  may  be  necessary  to  place 
one  or  more  bolts  in  position  to  hold  the  tree  shell  firmly  together. 
Iron  rods  and  wire  netting  are  also  sometimes  placed  in  the  hollow  to 
help  reinforce  the  concrete,  or  cement,  when  it  is  mixed  and  ready 
for  use.  The  tree  surgeon  learns  by  experience  the  best  methods  of 
procedure  in  the  use  of  bolts,  wire  netting  and  the  placing  of  the  filling 
substance. 

Mixing  and  Placing  the  Cement. — A  good  grade  of  Portland  cement 
and  clean,  sharp  sand  free  from  loam  (i  part  of  cement  to  3  or  less  of 
sand)  should  be  used.  The  mixing  can  be  done  in  a  mortar  bin,  a 
wheelbarrow,  a  pail,  or  in  any  other  available  receptacle.  A  mason's 
flat  trowel  and  an  ordinary  garden  trowel  with  a  curved  blade  will  be 
found  convenient  in  placing  the  cement.  A  tamping  stick,  one  or  two 
inches  thick  and  one  to  three  feet  long,  according  to  the  size  of  the  cavity, 
will  be  needed,  also  some  rocks  to  help  fill  the  cavity  and  a  pail  of 
water.  As  the  cement  begins  to  harden,  the  surface  should  be  carefully 
smoothed,  so  that  it  conforms  with  the  general  contour  of  the  tree  trunk. 
Sometimes  cloth,  or  wire  dams  are  used.  These  are  stretched  across 
the  opening  and  a  more  liquid  cement  is  poured  into  the  space  behind 


322 


GENERAL   PLANT   PATHOLOGY 


Fig.  131. — Cement  cavity  fillings,  showing  different  types  and  successive  stages. 
I,  A  large  cavity  in  an  elm  filled  with  cement  blocks  separated  by  layers  of  tarred 
paper;  a  patented  process.  2,  An  excavated  cavity  ready  for  treating  and  filling. 
3,  The  cavity  shown  in  2,  which  has  been  nailed  and  partly  filled  with  cement.  The 
ends  of  the  rods  for  reinforcing  the  concrete  are  sprung  into  shallow  holes  in  the  wood. 
The  wire  dam  is  sometimes  allowed  to  remain  embedded  in  the  cement,  though  it 
is  usually  removed  as  soon  as  the  cement  has  partially  set.  4,  A  later  stage  of  the 
work  shown  in  3.  The  height  of  the  wire  dam  has  been  increased.  5,  The  same 
cavity  shown  in  2,  3,  and  4,  several  days  after  the  filling  was  completed.  (After 
Collins,  F.  L.,  U.  S.  Yearbook  Dept.  Agric,  1913.) 


PRACTICAL  TREE  SURGERY  323 

the  dam  which  is  removed  when  the  fiUing  has  hardened.  Asphalt  and 
asphalt  mixtures  promise  much  for  the  future,  when  the  proper  methods 
of  applying  liquid  asphalt  have  been  discovered  (Fig.  131). 

Defects  in  cement  work  are  due  to  the  use  of  cheap  materials, 
carelessness  in  the  mixing  of  the  cement,  splitting  of  the  tree  by  the 
action  of  intense  cold,  dislodgment  of  the  cement  by  the  swaying  action 
of  the  wind.  Cracks  appear  in  the  cement,  if  the  wood  of  the  tree 
contracts  away  from  the  Ming,  or  by  the  spread  of  the  decayed  tissue 
behind  the  cement  work  due  to  lack  of  care  in  excavating  rotten  wood 
prior  to  the  filling  operation.     These  defects  may  cause  lots  of  trouble. 

Metal-covered  Cavities. — Sheet  tin,  zinc  and  iron  have  been  used 
extensively  to  cover  cavities.  These  coverings  often  serve  to  exclude 
rain,  fungous  organisms  and  destructive  insects  for  some  time.  If  not 
properly  applied,  such  tin-covered  cavities  are  a  greater  menace  to  the 
tree  than  open  cavities.  If  such  covers  are  used  at  all,  the  excavated 
cavity  should  be  thoroughly  sterilized  and  waterproofed.  The  metal 
is  nailed  fast  with  a  light  hammer  and  its  center  should  be  allowed 
to  curve  outward,  so  as  to  conform  to  the  general  shape  of  the  tree 
trunk.  The  tacked  edges  should  be  as  nearly  air-tight  and  water- 
proof as  it  is  possible  to  make  them,  and  this  can  be  assisted  by  paint- 
ing the  surface  of  the  tin.  Sometimes  fumigation  of  the  cavity  is 
resorted  to  as  an  added  precautionary  measure. 

Where  the  tree  is  not  of  sufficient  value  to  fill  with  cement,  an  open 
cleaned  cavity  may  be  left  after  cauterization  of  the  cleaned  wood 
surface  and  waterproofing.  A  layer  of  burned  wood  is  sometimes  a 
sufficient  protective  covering,  if  the  burning  is  accompHshed  by  one 
of  the  blow  lamps,  such  as  painters  use  for  stripping  the  paint  off 
woodwork. 

Guying. — Closely  associated  with  the  work  of  tree  surgery  proper, 
and  often  an  indispensable  adjunct  is  the  guying  of  limbs  to  prevent 
the  spHtting  of  the  crotches,  or  to  check  further  splitting.  Experience 
demonstrates  the  best  methods  of  applying  the  hook  bolts,  chains  or 
other  braces  to  the  trees  to  be  treated.  This  varies  so  widely  in  dif- 
ferent trees  that  it  is  impossible  to  give  specific  directions  for  this 
kind  of  work. 

In  conclusion,  it  should  be  stated  that  tree  surgery  can  be  under- 
taken safely  at  almost  any  season  of  the  year,  especially  well  when  the 
sap  is  not  flowing  actively,  and  the  weather  is  not  too  cold,  to  freeze 


324  GENERAL   PLANT   PATHOLOGY 

the  cement,  and  destroy  such  expensive  filling  work.  Most  ornamental 
and  shade  trees  having  only  a  few  dead  limbs  are  unquestionably  worth 
attention.  Others  which  have  many  dead  limbs,  or  numerous  decayed 
areas  may  not  be  worth  the  expense.  Trees  of  large  size,  rare  trees, 
historic  trees  and  trees  which  fill  a  peculiar  place  in  the  landscape  are 
probably  worth  saving  by  the  most  expensive  methods  of  tree  surgery, 
if  necessary.  Another  phase  of  tree  surgery  is  the  commercial  side, 
where  ignorant  men  and  tree  fakers  have  undertaken  to  make  a  business 
of  pruning  and  treating  trees.  The  sad  appearance  of  excessively 
pruned  trees  in  all  of  our  large  American  cities  are  living  spectacles  of 
the  zeal  of  such  men,  who  should  be  driven  out  of  the  business,  as  they 
have  in  Philadelphia  by  the  municipal  authorities  undertaking  to  do 
the  work  by  the  employment  of  skilled  tree  surgeons. 

Bailey,  L.  H.:  The  Pruning  Book.     The  Macmillan  Co.,  New  York,  1907. 
Blakeslee,  Albert  F.  and  Jarvis,  Chester  Deacon:  Trees  in  Winter.     Their 

Study  Planting  Care  and  Identification.  The  Macmillan  Co.,  New  York,  1913. 
Collins,  J.  Franklin:  Practical  Tree  Surgery.     Yearbook  of  the  United  States 

Department  of  Agriculture,  1913:  163-190. 
Gaskili,  Alfred:  The  Planting  and  Care  of  Shade  Trees. 

Forest  Park  Reservation  Commission  of  New  Jersey,  19 1 2,  with  papers  on  Insects 

Injurious  to  Shade  Trees  by  John  B.  Smith  and  Diseases  of  Shade  and  Forest 

Trees  by  Mel  T.  Cook. 
Start,  E.  A.  Stone,  G.  E.,  and  Fernald,  H.  T.:  Shade  Trees.     Bull.  125,  Mass. 

Agric.  Exper.  Sta.,  Oct.  i,  1908. 

It  has  been  a  matter  of  general  knowledge  that  a  disease  may  be 
controlled  by  a  change  in  the  time  of  planting,  for  with  smuts  the  very 
different  climatic  conditions  prevailing  at  the  time  of  the  various 
sowings  have  influenced  the  rate  of  infection.  Early  sowing  of  winter 
wheat  has  been  found  beneficial  in  the  reduction  of  the  amount  of 
stinking  smut,  for  wheat  sown  early  in  October  showed  no  sign  of  infec- 
tion, while  plants  sown  at  the  end  of  October  were  much  attacked 
(about  60  per  cent.)  by  the  smut.  By  experiment  as  a  problem  in 
prophylaxis  this  matter  of  sowing  as  a  means  of  controlling  disease 
should  be  established  for  all  of  our  important  cultivated  crops. 

Then  too,  a  study  of  the  cells  and  tissues  which  protect  plants 
against  the  entrance  of  insects  and  fungi  is  a  matter  of  prophylactic 
interest.  The  formation  of  cork,  of  bark,  of  callus,  of  how  in  response 
to  the  attack  of  fungi,  the  multiplication  of  protecting,  or  outer  cells, 
is  accomplished,  should  receive  the  attention  of  the  student  of  phyto- 


PRACTICAL  TREE  SURGERY  325 

pathology.  The  presence  of  tannin  and  other  protective  chemical 
substances  in   the  plant   may  explain  immunity  or  non-immunity.^ 

Disease  resistance  and  disease  susceptibility  are  understood  imper- 
fectly. The  determination  of  the  cause  of  the  inherent  differences  in 
the  tendency  of  this  or  that  variety  to  suffer  from  disease  is  a  matter 
of  great  importance.  Breeding  for  disease  resistance  is  a  promising 
field  of  research. 2  Something  has  been  accomplished  along  this  line, 
but  the  amount  which  we  do  not  know  vastly  exceeds  the  knowledge 
which  we  now  possess.  Rustproof  varieties  of  wheat  have  been  ob- 
tained. At  the  Ohio  Experiment  Station  by  selection  of  hills  of 
potatoes  that  withstood  attacks  of  the  early  blight  fungus  and  planting 
tubers  therefrom  with  subsequent  repetition  of  this  line  of  work,  early 
blight  resistant  strains  were  secured.  Progress  has  been  made  with 
cotton  resistant  to  wilt  and  with  musk  melons  resistant  to  leaf  blight. 

Recently  Jones  and  Oilman^,  Wisconsin,  have  undertaken  to  con- 
trol the  disease  known  as  yellows  caused  by  the  parasitic  soil  fungus, 
Fusarium  conglutinans,  by  breeding  cabbage  plants  that  show  disease 
resistance.  By  repeated  selection  of  the  occasional  sound  heads  in 
fields  of  diseased  cabbages,  strains  of  winter  cabbage  of  the  Hollander 
type  have  been  secured  which  have  proved  in  a  high  degree  resistant 
against  the  attacks  of  Fusarium.  The  chances  for  research  along  these 
lines  are  practically  unlimited  and  full  of  promise  for  the  future  of 
agriculture  and  horticulture. 

1  Cook,  Mel  T.  and  Taubenhaus,  J.  J. :  The  Relation  of  Parasitic  Fungi  to 
the  Contents  of  the  Cells  of  the  Host  Plants,  (i.  The  Toxicity  of  the  Tannins) 
Bull.  91,  Del.  Agric.  Exper.  Stat.,  February,  1911. 

2  Orton,  W.  a.  :  The  Development  of  Farm  Crops  resistant  to  Disease.  Year- 
book of  the  United  States  Department  of  Agriculture,  1908:  453-464. 

3  Jones,  L.  R.  and  Oilman,  J.  C. :  The  Control  of  Cabbage  Yellows  through 
Disease  Resistance.  Research  Bull.  38,  Agric.  Exper.  Stat.  Univ.  Wis.,  December, 
1915;  Norton,  J.  B.:  Methods  used  in  Breeding  Asparagus  for  Rust  Resistance, 
U.  S.  Bureau  of  Plant  Industry,  Bull.  263,  1913. 


CHAPTER  XXVI 
INTERNAL  CAUSES  OF  DISEASE 

During  recent  years  attention  has  been  called  to  diseases  which  are 
evidently  due  to  the  action  of  an  enzyme,  or  ferment  in  the  plant, 
which  renews  itself  perhaps  as  a  catalytic  agent  in  the  tissues  of  the 
host.  As  it  is  filterable  through  a  Berkefeld  filter,  it  may  be  a  soluble 
enzyme  pure  and  simple,  or  it  may  be  one  of  the  extremely  minute, 
ultra-microscopic  organisms  to  which  attention  has  been  called  recently. 
All  the  evidence  seems  to  point  to  its  enzymatic  nature.  Such  diseases 
are  caused  by  the  excessive  activity  of  the  oxidase  and  peroxidase 
enzymes  in  the  plant  and  the  loss  of  function  of  catalase,  another  en- 
zyme, which  carries  off  some  of  the  residual  products  of  the  others 
mentioned.  Such  diseases  due  to  a  Contagiimi  viviim  fluidum  affect  a 
number  of  plants,  notably  the  tobacco,  and  all  of  these  diseases  seem 
to  be  more  or  less  related,  as  to  their  nature  and  origin.  Recently 
Kiister  in  the  second  edition  of  his  "Pathological  Plant  Anatomy" 
(191 6)  has  grouped  many  of  the  enzyme-produced  conditions  under 
the  head  of  "Panaschiering."  He  distinguishes  several  types.  The 
first  is  when  the  green  parts  contract  sharply  under  the  pale  parts. 
Under  this  head  he  considers:  (a)  marginal  panaschiering,  when  such 
terms  as  "albo-marginatis"  would  be  applicable,  as  in  such  cultivated 
plants  as  Pelargonium  zonale,  Hedera  helix  and  Weigelia  rosea,  (b) 
In  sectional  panaschiering,  the  white  and  the  green  colors  are  dis- 
tributed sectionally  over  leaves  and  stems,  as  in  Chamaecyparis  pisi- 
fera  plumosa  argentea.  (c)  He  distinguishes  marbled  and  pulverulent 
panaschiering.  His  second  group  includes  cases  where  the  border 
between  green  and  pale  parts  is  not  sharply  marked  and  this  group 
includes  {a)  Zebra-panaschiering,  as  in  the  banded  leaves  of  Etdalia, 
and  (b)  flecked  panaschiering,  where  white  specks  are  distributed  over 
a  green  background  and  blend  with  it.  It  is  clear  that  "Mosaic," 
"Brindle,"  "Calico"  or  "Mottle  Top"  of  tobacco  is  a  physiologic, 
not  a  fungous  or  bacterial  disease. 

326 


INTERNAL   CAUSES    OF   DISEASE  327 

It  is  infectious,  and  to  a  certain  extent  contagious.  As  calico  is  an 
important  disease  of  tobacco  and  tomato  a  description  of  it  in  these 
plants  will  serve  to  show  what  enzyme  diseases  are  like  in  general. 
The  leaves  present  a  mottled  appearance,  being  divided  into  smaller,  or 
larger,  areas  of  light-green  and  dark-green  patches.  In  the  tomato,  the 
light-green  areas  become  yellowish,  as  the  disease  progresses,  and  in 
very  badly  affected  plants  become  finally  purplish-red  in  color.  The 
leaves  are  much  distorted,  stiff,  and  badly  curled.  It  attacks  other 
plants,  notably  the  poke  weed.  Phytolacca  decandra,  ragweed,  Am- 
brosia artemisicBfolia,  Jamestown  weed.  Datura  stramonium.  It  is 
probable  that  peach  "yellows,"  aster  "yellows"  are  more  or  less  similar 
to  the  true  "mosaic."  Calico  is  primarily  a  disease  of  the  green  color- 
ing matter  (chlorophyll)  of  the  infected  plants;  hence  it  disturbs  the 
normal  nutrition  of  the  plant.  To  this  destruction  of  the  chlorophyll 
the  name  of  chlorosis  has  been  given  and  calico  is,  therefore,  a  state  of 
chlorosis.  The  contagious  nature  of  calico  is  shown  by  experiments 
which  prove  that  it  can  be  communicated  at  least  in  some  cases  by 
mere  contact  of  calicoed  plants  with  the  healthy.  Juice  on  the  hands 
from  calicoed  plants  when  handling  disease-free  plants  will  spread  the 
disease  in  nearly  all  cases,  and  this  infection  is  due  to  the  chlorotic  juice 
on  the  hands  of  the  experimenter.  Chlorosis,  or  calico,  usually  takes 
ten  to  fourteen  days  to  make  its  appearance  after  infection  and  a  plant 
once  infected  remains  permanently  so,  and  all  new  growth  usually 
becomes  calicoed.  Calico,  or  mosaic,  can  be  transferred  to  other  species 
and  varities  of  Nicotiana  than  the  common  N.  iabacum,  also  to  potato, 
egg  plant,  peppers,  petunia,  etc.  The  dried  leaves  of  calicoed  tobacco 
retain  their  power  of  infection  for  at  least  a  year  or  two,  to  some  degree, 
but  if  wetted  they  lose  this  power.  The  virus,  if  it  is  permissible  to 
use  this  word,  can  be  apparently  extracted  from  calicoed  leaves  by 
ether,  chloroform  and  alcohol  without  destroying  its  infectious  qualities. 
Bunzel  has  measured  the  oxidase  content  of  plant  juices,  because  of  the 
importance  of  oxidase  in  chlorotic  diseases  of  plants,  in  their  causal 
relationship  to  color  production  in  plants,  their  importance  in  the  dark- 
ening of  tea  and  in  the  production  of  the  smooth,  black  and  hard 
lacquer  of  the  Japanese,  from  the  white,  fluid,  soft  secretion  of  the 
lacquer  tree,  Rhus  vernicifera.  The  literature  on  oxidizing  enzymes 
is  a  copious  one.  The  following  papers  and  books  can  be  consulted, 
as  well  as  the  bibliography  which  each  includes: 


328  GENERAL  PLANT  PATHOLOGY 

BuNZEL,  Herbert  H.  :  The  Measurement  of  the  Oxidase  Content  of  Plant  Juices. 

Bull.  238,  Bureau  of  Plant  Industry,  U.  S.  Dept.  Agric.,  191 2. 
Chapman,  G.  H.  :  Mosaic  and  Allied  Diseases  with  Especial  Reference  to  Tobacco 

and  Tomato.  2sth  Annual  Report  Mass.  Agric.  Exper.  Stat.,  1913:  94-104. 
Clinton,  G.  P.:  Chlorosis  of  Plants  with  Special  Reference  to  Calico  of  Tobacco. 

Report  Conn.  Agric.  Exper.  Stat.,  New  Hav^en,  1914:  357-424,  with  8  plates. 
Kastle,  J.  H. :  The  Oxidases  and  other  Oxygen  Catalysts  concerned  in  Biological 

Oxidations.     Bull.  59,  U.  S.  Hygienic  Lab.,  1910. 
Klebahn,    Professor    Dr.    H.:    Grundziige    der    Allgemeinen     Phytopathologie, 

191 2:  124-127. 
Woods,  Albert  F.:  Observations  on  the  Mosaic  Disease  of  Tobacco.     Bull.  18, 

Bureau  of  Plant  Industry,  U.  S.  Dept.  Agric,  1902. 

Nutritive  disturbances  may  also  be  included  as  internal  causes  of 
disease.  If  for  any  reason,  such  as  the  inability  of  the  living  cells  of 
the  root  to  take  up  water  through  a  change  in  the  osmotic  power  of  the 
protoplasmic  membrane  of  the  root  hair  cells,  the  leaves  above  owing 
to  active  transpiration  cannot  secure  sufficient  quantities  of  water 
and  the  whole  plant  wilts.  A  disturbance  in  the  formation  of  starch 
in  the  chloroplast  results  in  a  deficiency  of  the  plastic  carbohydrates, 
and  the  active  cells  of  the  cambium  during  this  period  of  starvation 
form  less  wood  and,  therefore,  fewer  conducting  vessels.  This  reacts 
on  the  tissues  everywhere  in  the  plant  by  reducing  the  available  water 
and  food  and,  therefore,  the  plant  is  dwarfed  and  perhaps  sickly. 
Intumescences  are  trichomatous  outgrowths  not  associated  with 
insects  or  fungi  which  are  due  to  some  disturbance  of  the  balance 
between  transpiration  and  assimilation. 

Mutations  which  result  in  the  sterility  of  an  annual  species  would 
lead  to  the  extinction  of  the  plant  with  such  non-seed  production. 
(Enothera  albida  is  a  pale-green,  rather  brittle  and  very  delicate  form 
with  narrow  leaves;  never  attaining  anything  like  the  height  of  (E. 
Lamarckiana.  It  bears  pale  flowers  and  weak  fruits  which  contain 
little  seed.  It  appears  every  year  in  most  of  de  Vries's  cultures  in 
larger  or  smaller  numbers.  The  plants  are  so  weak  that  de  Vries 
imagined  them  to  be  diseased,^  and  after  much  difficulty  he  secured 
seeds  from  them.  Enough  has  been  given  on  these  points  to  show  that 
mutations  may  be  along  the  line  of  plants  constitutionally  weak. 
The  absence  of  amygdalin  and  prussic  acid  in  the  Sweet  Almond 
may  make  such  a  form  more  susceptible  to  disease,  as  also  the  absence 
of  quinine  from  cinchona  trees  kept  in  European  hot  houses. 

^DE  Vries,  Hugo:  The  Mutation  Theory  (English  edition),  I:  229,  1909. 


internal  causes  of  disease  329 

Malformations  and  Monstrosities 

Hugo  de  Vries  has  shown  that  malformations  and  monstrosities 
do  not  arise  as  a  result  of  variations,  but  may  be  looked  upon  as  muta- 
tions. His  tricotylous,  hemisyncotylous,  syncotylous,  and  amphi- 
syncotylous  races  are  proof  of  this  statement.  Fasciation  in  its 
simplest  form  consists  of  a  flat,  ribbon-like  expansion  of  stem, 
branch,  flower  clusters,  flowers  and  fruits  which  may  be  cylindric 
below,  but  flattened  above.  This  is  one  of  the  most  common  of  all 
malformations  and  by  numerous  experimental  cultures  the  fasciation 
has  been  found  to  be  heritable.  Spirally  twisted  plants  are  more 
striking  malformations  than  fasciations.  Valeriana  officinalis  is 
one  of  the  best-known  examples  displaying  spiral  torsion.  It  is  also 
displayed  in  a  teasle.  Dipsacus  silvestris  torsus,  twisted  sweet  william, 
Dianthiis  barbatus,  dark-eyed  Viscaria,  Viscaria  oculata.  Such  mal- 
formations de  Vries  has  shown  to  be  truly  heritable.  (Pleiphylly  is 
that  condition  where  two  or  more  leaves  arise  in  place  of  a  single  one.} 
Such  we  find  in  the  ever-sporting  races  of  clovers,  where  four,  five, 
six,  seven,  or  even  eight  leaves  appear  instead  of  the  normal  three. 
The  presence  of  three  leaves  in  a  whorl,  or  of  three  cotyledons,  as  above 
noted,  is  called  polyphylly.  Shull  has  shown  that  the  ascidial 
leaflets  of  the  white  ash,  Fraxinus  americanus,  are  heritable.  Pistil- 
lody  is  demonstrated  in  the  appearance  of  imperfect  pistils  in  place  of 
stamens,  as  in  the  poppy.  When  colored  flower  parts  become  green, 
this  condition  is  known  as  antholysis,  or  chloranthy,  and  is  illustrated 
in  green  roses  and  green  dahlias.  This  condition  and  petalody  and 
sepalody  are  transmitted.  Peloria,  where  a  normally  zygomorphic 
flower,  as  in  the  toad-flax,  Linaria  vulgaris,  is  transformed  into  a  regular 
flower  with  five  spurred  petals  instead  of  one  spurred  petal,  is 
another  example  of  monstrosities  which  are  heritable. 

The  history  of  Cytisus  Adami  which  originated  as  a  graft  hybrid 
is  of  interest  in  connection  with  the  study  of  Chimaeras.  Hybrids  that 
arise  by  vegetative  reproduction,  where  scion  and  stock  are  mutually 
affected,  are  known  as  graft  hybrids.  The  origin  of  Cytisus  Adami 
seems  to  have  been  as  follows:  a  shoot  of  Cytisus  purpureus  was 
grafted  on  a  stock  of  Cytisus  laburnum;  from  this  were  produced  many 
shoots,  one  of  which  grew  vigorously,  and  developed  larger  leaves 
than  those  of  C.  purpurcus  and  from  this  shoot  plants  were  propagated 


330  GENERAL   PLANT   PATHOLOGY 

constituting  Cytisus  Adami.  It  was  found,  that  on  flowering,  this 
form  had  dingy  red  flowers.  Winkler  believes  that  graft  hybrids  and 
chimaeras  are  the  result  of  the  process  by  which  cells  of  two  distinct 
kinds  or  species  are  united  vegetatively  instead  of  by  sexual  methods, 
and  that  this  serves  as  the  point  of  departure  for  an  organism  which  in 
a  single  growth  shows  bound  together  the  peculiarities  of  both  species. 
Hence,  a  graft  hybrid  is  a  complex  chimgera.  Baur  thinks  that  the 
union  between  CratcBgus  and  Mespilus  {Crafa gomes pilus)  is  a  periclinal 
chimgera,  and  refers  this  and  the  graft  hybrid  to  the  development  of  a 
mixed  vegetation  point,  where  the  periclinal  chimaera  originates  in 
the  development  of  an  apical  region  with  a  periclinal  arrangement 
of  cells.  ^ 

Branches  of  shrubs  and  trees  originate  as  mutants  with  a  dififerent 
combination  of  characters  than  the  rest  of  the  shrub,  or  trees.  Such 
mutants  probably  arise  in  the  change  of  some  single  cell.  The  shoot 
which  arises  from  tissue  formed  by  mutating  cells  develops  into 
something  new  which  is  called  a  bud  variation,  or  sport  variety.  If 
the  shoot  arises  from  the  mutating  cells  alone,  then  the  resulting 
shoot  will  consist  only  of  the  new  cells  an^  the  sport  can  be  propagated 
true  without  any  reversion.  If  the  tissue  which  gives  rise  to  the  shoot 
combines  both  old  and  new  cells,  then  there  arises  a  mixed  branch, 
which  is  known  as  a  "sectorial  chimaera."  Citrus  treess  how  such 
"sectorial  chimaeras"  not  infrequently  when  a  Valencia  orange  tree 
bears  typical  Valencia  oranges  and  a  small  rough  and  worthless  muta- 
tion. A  twig  here  and  there  produces  oranges  in  which  certain  sectors 
of  the  fruits  show  mutant  tissue,"  forming  what  may  be  called  mixed 
oranges.  These  have  probably  arisen  because  the  mutant  tissue  is 
scattered  or  mixed  with  the  tissue  of  the  original  form  thus  constituting 
a  "hyper  chimaera." 

"Mutations  often  occur  in  the  cells  which  begin  the  formation  of 
the  minute  ovaries  in  the  blossom  buds.  As  the  ovary  grows  in  size, 
the  mutation  appears  as  a  sector  of  the  fruit  which  differs  in  color, 
ripening  season,  or  thickness  of  skin  from  the  rest  of  the  fruit.  Such 
curious  fruits  have  been  called  spontaneous  chimaeras"  (Coit). 

1  Winkler,  H.:  Ueber  Pfropfbastarde  und  Pflanzliche  Chimaren.  Ber. 
Deutsch.  Bot.  Gesellsch.,  25:  568-576,  1907;  Baur,  E.:  Pfropfbastarde,  Periklinal 
chimaren  und  Hyperchimaren,  Do.,  27:  603-605,  1909. 

2  Coit,  J.  Eliot:  Citrus  Fruits,  1915:  121-122. 


CHAPTER  XXVII 
CLASSIFICATION  OF  PLANT  ABNORMALITIES 

The  older  botanists  prior  to  the  pubHcation  of  the  important  work 
of  Maxwell  T.  Masters  in  1869  gave  little  attention  to  abnormalities  in 
plants.  Linnaeus  treated  of  them  to  some  extent  in  his  ''Philosophia," 
but  it  is  mainly  to  Augustin  Pyramus  de  Candolle  that  the  credit  is 
due  of  calling  attention  to  the  importance  of  vegetable  teratology,  as 
throwing  light  upon  normal  structure  and  functions.  Until  the  epoch- 
making  work  of  de  Vries  on  plant  mutations  drew  attention  to  the 
absolute  necessity  of  experimental  methods  in  the  study  of  normal  and 
teratologic  plants,  the  field  of  vegetable  teratology  was  the  concern  of 
the  plant  morphologist  and  the  different  abnormalities  were  studied  by 
comparative  morphologic  methods.  Hugo  de  Vries  and  several  of 
his  co-workers  pointed  out  that  many  abnormal  forms  are  heritable  and 
this  suggested  that  the  line  of  approach  in  their  study  was  through 
experiments  in  breeding  these  forms  to  discover  their  origin  and 
true  character.  This  has  been  done  with  a  few  forms,  but  the  whole 
field  should  be  worked  by  some  competent  geneticist,  who  would  devote 
his  life  to  the  undertaking.  Without  further  discussion,  it  has  been 
thought  advisable  to  put  in  a  form  accessible  to  American  college 
students,  a  glossary  of  the  more  important  terms  used  in  teratology. 
With  the  exception  of  a  few  additions  the  terms  given  in  first  volume 
of  "  Pflanzen-Teratologie"  (1890)  by  Dr.  0.  Penzig  are  here  translated 
from  the  original,  as  serving  as  an  outline  of  teratology  for  American 
students. 

Abortion  (Masters  and  English  authors;  Abortus,  German  Avortion 
or  Avortement,  French)— Stunting  of  an  organ,  that  is  the  exceptionally 
small  formation  of  the  same,  whereby  the  form  remains  unchanged. 
The  German  and  French  authors  use  the  same  expression  very  fre- 
quently for  the  cases  where  a  certain  organ  is  entirely  suppressed  and 
does  not  make  an  appearance. 

Acaiilosy. — Acaulosia  is  the  diminution  in  the  size  of  the  stem,  for 
absolute    suppression    of    the    stem,    as    the    terms   acaulescent   and 

331 


332  GENERAL   PLANT   PATHOLOGY 

acaulosia  would  signify,  is  an  impossibility  in  a  typic  plant.  The  term 
is  purely  a  relative  one. 

Acheilary  (Ch.  Morren). — The  suppression  of  the  labellum  in  such 
flowers  as  the  Orchidace^. 

Adesmy  (Ch.  Morren). — Congenital  separation  of  organs  which 
are  normally  united  together,  therefore,  often  included  as  atavism. 
Morren  distinguishes  between  homologous  adesmy  as  the  separation 
of  members  of  one  whorl  and  heterologous  adesmy  the  separation  of  the 
members  of  one  whorl  from  those  of  another. 

Adenopetaly. — Formation  of  a  nectary  in  a  former  nectarless  petal. 

Adhesion.^ — Normally  used  for  the  union  of  parts  of  different  whorls 
in  the  flower,  for  example,  the  union  of  a  sepal  with  a  petal,  or  of  a 
stamen  with  a  carpel,  and  also  for  fusion  in  general  (of  a  branch  with 
the  main  axis,  of  a  leaf  with  a  branch,  etc.). 

Adherence  (Moquin-Tandon). — Fusion  of  organs  which  normally 
are  separate. 

Anaeretic  (Schimper,  1854).^ — Vnder  foli alio  anceretka,  C.  Schimper 
obviously  understood  the  abnormal  arrangement  of  leaves  on  an  axis 
in  a  single  row,  a  condition  sometimes  produced  by  a  torsion,  or  twisting 
of  the  axis. 

Antherophylly  (Ch.  Morren).- — Formation  of  anthers  upon  leaf 
blades. 

Anthesmolysis  (Engelmann). — Central  or  lateral  metamorphosis 
of  an  inflorescence,  especiafly  of  heads  as  in  the  Dispaceae  and 
Compositse. 

Antholysis  (Spenner  in  Flor.  Friburg). — A  solution  of  flowers, 
particularly  applied  to  the  condition  in  which  the  axis  becomes  elongated 
and  the  flower  whorls  separated  from  each  other. 

Aphylly.^ — The  condition  of  the  plant  in  which  leaves  are  suppressed. 

Apilary  (Ch.  Morren). — Suppression  of  the  upper  lip  in  normally 
bilabiate  flowers,  as  in  Calceolaria. 

Apogamy.- — Vegetative  reproduction  of  plant  individuals  instead 
of  by  the  usual  method  with  sex  organs,  especially  used  with  reference 
to  ferns  where  the  antheridia  and  archegonia  are  suppressed  or  not 
functional,  the  young  plant  arising  directly  from  the  prothallium.  If 
is  also  used  for  the  non-sexual  formation  of  embryos  in  the  embryo  sac 
of  the  phanerogams. 

Apophysis. — Vegetative,  central  proliferation  of  an  inflorescence. 


CLASSIFICATION    OF   PLANT   ABNORMALITIES  ^^^ 

Apostasis. — The  monstrous  disunion  of  parts  normally  united  as 
in  the  elongation  of  a  flower  axis,  as  a  result  of  which  the  whorls  are 
transformed  into  spirals.  One,  however,  uses  the  term  for  the  sepa- 
ration of  single  floral  phyllomes,  for  example  single  sepals  from  the 
calycine  whorl. 

Atrophy. — Wasting  away;  degeneration  of  organs;  abortion. 

Autophyllogeny  (Ch.  Morren). — The  budding  of  one  leaf  from 
another,  as  from  the  midrib. 

Balance  Organic  (Moquin-Tandon).^One  uses  this  expression  for 
cases  that  by  atrophy  of  single  organs  of  a  plant  is  compensated  by 
hypertrophy  of  others. 

Biastrepsis  (C.  Schimper). — This  is  analogous  to  the  torsion,  or 
twisting  of  other  authors. 

Blastomany  (A,  Braun). — Abnormal  tendency  of  single  plant 
individuals  to  develop  an  unusual  number  of  leaf  buds  (axillary  or 
adventitious). 

Calycanthemy  (Masters). — Transformation  of  sepals  to  petaloid 
structure. 

Calyphyomy  (Ch.  Morren). — Adhesion  of  one  or  all  of  the  sepals  to 
the  back  of  the  petals. 

Cenanthy  (Ch.  Morren).- — Kevds  =  empty  +  avdos  =  flower:  Abor- 
tion, or  suppression  of  the  stamens  and  pistils  of  a  flower,  leaving  the 
perianth  empty. 

Ceratomany. — Abnormal  formation  of  horn-like,  or  hooded,  fre- 
quently nectariferous  structures  in  a  flower.  Clos  has  employed  the 
same  term  for  the  increase  in  the  spurs  in  many  families  (Orchidace^)  . 

Chellomany  (Ch.  Morren). — The  doubling  of  the  lip,  or  labellum, 
in  orchids,  as  in  Orchis  morio. 

Chloranthy. — The  transformation,  or  change  of  all  or  most  of  the 
floral  parts  into  leaf-like  green  parts;    frondescence. 

Chorisis. — The  separation  of  a  leaf  or  phylloid  part  into  more  than 
one;  dedoublement,  doubling. 

Cladomany. — An  abnormally  richly  branched  plant. 

Cohesion. — A  union  between  the  members  of  one  and  the  same 
whorl  (particularly  in  flowers),  or  between  the  parts  of  a  composite 
organ. 

Coryphylly. — An  abnormality  in  which  a  leaf  ends  the  axis.  This 
leaf  is  sometimes  colored. 


334 


GENERAL   PLANT   PATHOLOGY 


Crateria.^ — C.  Schimper  uses  this  term  for  a  leaf  blade  which  de- 
velops ascidia,  as  the  ascidial  white  ash  discovered  by  George  H.  Shull. 

Cyclochorisis  (Fermond). — Division  of  an  axial  organ  in  two  direc- 
tions, so  that  in  place  of  a  simple  axis  there  arise  whole  clusters  of 
secondary  axes. 

Dedoublement  (chorisis,  doubling)  .^ — Congenital  division  of  an 
organ  in  which  several  parts  arise  out  of  a  single  primordium.  Lateral 
and  serial  dedoublement  are  distinguishable. 


Fig.  132. — Twin  cherries  due  to  dialysis,  or  disjunction,  of  the  pistil  of  the  flower 
into  two  carpels,  each  of  which  matures  into  perfect  drupe  joined  at  the  base  with 
its  fellow.     Philadelphia  Market,  May  25,  1916. 

Deformation.^ — A  malformation,  or  alteration  from  the  normal 
kind.  A  general  expression  for  the  irregular  formation  of  an  organ, 
or  a  complex  of  organs. 

Degeneration  (Masters) .^ — Stunted  formation  of  an  organ  with 
which  changes  of  form  are  associated.     An  alteration  for  the  worse. 

Dialysis  (Ch.  Morren,  Masters). — The  separation  of  parts  normally 
in  one,  especially  parts  of  the  same  whorl.  Scarcely  distinguishable 
from  adesmy  (Fig.  132). 

Diaphysis  (Engelmann).— A  central  proliferation  of  flowers.  If 
the  flower  axis  elongated  beyond  the  carpels  bears  another  flower,  we 


CLASSIFICATION    OF   PLANT   ABNORMALITIES  335 

speak  of  Diaphysis  floriparous;  if  leafy  shoots  arise,  it  is  Diaphysis 
frondiparons;  if  a  cluster  of  flowers,  it  is  known  as  Diaphysis 
racemiparous. 

Diplasy  (Fermond). — The  division  of  an  axial  organ  into  two 
parts. 

Diremption.^ — The  occasional  separation,  or  displacement  of  leaves. 

Diruption. — A  term  used  by  Germain  de  St.  Pierre  for  different 
appearances  (division  of  leaves,  axes,  fasciation). 

Discentration  (C.  Schimper).^ — A  term  applied  to  fasciation  of  an 
axial  organ,  but  used  occasionally  for  the  multiple  division  of  a 
phyllome. 

Displacement  (Masters). — The  abnormal  position  of  a  plant  organ. 

Distrophy  (Re). — The  dissimilar  formation  of  the  homologous 
organs  of  a  plant. 

Divulsion  (St.  Germain  de  Pierre).- — See  diruption. 

Ecblastesis  (Engelmann).^ — ^Lateral  proliferation,  that  is  bud  for- 
mation in  the  axils  of  flower  parts  (sepals,  petals,  stamens  or  carpels). 
There  can  be  distinguished  floriparous,  frondiparous  and  racemiparous 
kinds  of  ecblastesis. 

Enation.^ — The  formation  of  excrescences  of  different  kinds  on  the 
upper  surface  of  other  organs.  We  find  scales  projecting  from  petals, 
small  lamina  on  foliage,  leaves,  etc. 

Epanody  (Ch.  Morren). — Abnormal  reversion  of  an  organ  to  a 
simpler  form  than  it  normally  shows. 

Epipedochorisis  (Fermond).- — A  manifold  division  of  an  axial 
organ  in  one  plane.     Frequently  not  distinguishable  from  fasciation. 

Epistrophy  (Ch.  Morren). — A  reversion  of  an  apparently  constant 
monstrosity  to  the  normal  form  of  single  organs,  for  example,  the 
development  of  branches  with  normal  leaves  in  place  of  those  with  cleft 
leaves. 

Etiolated. — Blanched,  or  lengthened  abnormally  by  the  absence  of 
light. 

Expansivity .^ — A  term  used  by  Germain  de  St.  Pierre  with  a  similar 
sense  to  Diruption  and  Divulsion. 

Fasciation  (Olaus  Borrich,  i67i).^A  flat  band-like,  or  ribbon-like 
expansion  of  a  normal  cylindric  axis,  or  stem,  associated  with  departure 
from  the  normal  leaf  position.  If  flowers  are  developed  they  are 
generally  altered  in  structure  (Fig.  133). 


336 


GENERAL   PLANT   PATHOLOGY 


Fission. — A  division  of  a  normally  simple  organ. 

Frondescence.^ — The  prolifer- 
ation of  a  normally  reduced  petal 
to  a  foliage  leaf  with  lamina. 

Gamomery  (Engelmann). — 
The  condition  in  which  the 
normally  distinct  petals  are 
united  into  a  gamopetalous 
corolla. 

Gemmiparity. — The  condtion 
of  leaves  which  develop  adventi- 
tious buds. 

Gymnaxony  (Ch.  Morren).— 
The  condition  in  which  the 
placenta  protrudes  through  the 
ovary  of  the  flower. 

Gynophylly  (Ch.  Morren). — 
The  transformation  of  a  carpel 
into  a  foliage  leaf.  Phyllomor- 
phy  of  the  ovary. 

Hemitery. — An  abnormality 
of  elementary  organs,  or  of  axial 
appendages. 

Heterogamy  (Masters). — An 
alteration  in  the  position  of  the 
sexual  organs. 

Heteromorphy  (Masters). — 
Irregular  formation  of  an  organ. 

Heterotaxy. — This  term  is 
used  by  Masters  for  the  cases  in 
which  a  new  organ,  or  structure, 
appears  in  unusual  places,  as  leaf 
buds  and  flower  buds  on  a  root. 
Later  authors  (Freyhold)  use  the 
word  in  an  entirely  different  sense 
for  the  inversion  of  the  floral  plan. 

Homotypy. — The  develop- 
ment of  an  organ,  or  of  any 
structure  in  the  same  place,  where  normally  another  one  originates. 


Fig.  133. — Fasciated  stem  and  fruits  o^ 
the  poppy  {Papaver).  {Drawing  by  Alice  M- 
Russell.) 


CLASSIFICATION   OF   PLANT   ABNORMALITIES  337 

Hypertrophy. — An  abnormal  largeness,  strong  formations  of  any 
plant  part. 

Idiotery. — A  monstrosity  by  which  a  plant  departs  from  the  normal 
type  and  from  all  of  its  related  forms. 

Lepyrophylly  (Ch.  Morren). — The  transformation  of  the  integu- 
ments of  the  ovule  into  scales,  or  leaves. 

Meiophylly. — The  diminution  in  the  number  of  leaves  in  a  whorl,  as 
compared  with  those  of  the  preceding  whorl. 

Meiotaxy.— The  suppression  of  entire  whorls. 

Metamorphosis. — The  transformation  of  an  organ  into  another  one, 
that  is  morphologically  equivalent  to  it,  but  it  may  be  has  a  wholly 
different  appearance  and  other  functions. 

Metaphery  (Ch.  Morren)  .^ — The  displacement  of  organs,  as  when 
alternate  become  opposite. 

Metastasis  (Moquin-Tandon). — The  shifting  of  an  organ  to  some 
unusual  position. 

Mischomany  (Ch.  Morren). — An  increase  in  the  number  of  pedicels 
or  the  branching  of  the  inflorescence,  as  in  Muscari  comosum. 

Monosy  (Ch.  Morren). — Separation  of  floral  parts  from  one  another 
with  which  they  normally  are  in  Cohesion,  or  Adhesion.  The  abnormal 
isolation  of  parts  due  to  a  desmy  or  dialysis. 

Multiplication. — The  division  of  an  order  into  many  homologous 
parts. 

Oolysis. — A  greening  (viridescence)  which  shows  conspicuously 
in  the  carpels  and  ovules  of  the  flowers. 

Peloria  (Linnaeus). — The  radial  (actinomorphic)  regular  formation 
of  a  normal  zygomorphic  (irregular)  flower. 

Periphyllogeny  (Weinmann). — The  formation  of  numerous  leaflets 
about  the  border  of  a  leaf  blade. 

Permutation  (De  CandoUe). — An  enlargement  of  the  floral  envelopes 
with  corresponding  abortion  of  the  sexual  organs. 

Petalody. — The  metamorphosis  of  stamens,  or  other  organs  into 
petals  with  their  usual  form,  color  and  consistence. 

Petalomania. — An  abnormal  multiplication  of  petals. 

Phyllocally  (Lemaire). — The  budding  of  new  leaflets  on  the  surface 
of  foliage  leaves. 

Phyllody  (Masters). — The  appearance  of  foliage  leaves  in  place  of 
floral  ones. 


338  GENERAL   PLANT    PATHOLOGY 

Phyllomania. — An  abnormal  production  of  green  leaves. 

Pistillody  — The  transformation  of  floral  parts  into  carpels. 

Pleiomorphy  (Masters). — An  abnormal  or  excessive  development. 

Pleiophylly  (Masters)  .^ — The  appearance  of  many  leaves  in  place  of 
a  single  part. 

Pleiotaxy  (Masters). — The  increase  in  the  number  of  whorls  in  a 
flower. 

Plesiasmy  (Fermond). — An  abnormal  shortening  of  the  stem  inter- 
nodes,  so  that  the  leaves  are  arranged  closely  together. 

Pollaplasy  (Fermond). — The  division  of  a  theoretic  simple  organ 
into  many  analogous  structures. 

Polyclady. — An  unusual  development  of  branches  and  twigs. 

Polyphylly. — The  abnormal  increase  in  the  number  of  parts  of  the 
floral  whorls. 

Prolification. — This  term  is  used  with  a  number  of  different 
meanings.  One  is  the  central,  or  lateral,  outgrowth  from  a  flower,  or 
an  inflorescence.  The  different  kinds  are  designated  as  median,  axil- 
lary, extrafloral,  while  each  kind  is  again  divided  into  foliar  and  floral, 
depending  upon  the  nature  of  the  adventitious  bud.  The  axillary 
prolification  is  known  as  echlastesis  (Engelmann)  and  the  median  as 
diaphysis. 

Rachitism  (Touchy). — Hypertrophy  of  the  floral  envelopes,  as  in 

JUNCACE.E,  CyPERACE^,   GrAMINACE.E. 

Recrudescence.- — The  production  of  a  leafy,  or  flowering,  shoot  from 
an  axis  of  inflorescence  after  the  formation  of  ripe  fruit  on  that  axis, 

Rhizocallesy  (Ch.  Morren). — The  union  of  two  plants  of  the  same 
species  solely  by  their  roots. 

Salpinganthy  (Ch.  Morren).— The  transformation  of  ligulate  or 
ray  florets  of  Compositae  into  conspicuous  tubular  florets. 

Scyphogeny  (Ch.  Morren). — The  formation  of  ascidia  from  leaf 
blades. 

Sepalody.^The  transformation  of  petals  into  sepals,  or  sepaloid 
parts. 

Solenoidy.  (Ch  Morren). — The  metamorphosis  of  stamens  into 
tubular  structures. 

Solution  (Masters)  .^ — Abnormal  separation  of  the  members  .of  a 
whorl  from  those  of  another  (similar  to  the  Adesmia  heterologous  of 
Morren). 


CLASSIFICATION   OF   PLANT   ABNORMALITIES  339 

Sphaerochorisis  (Fermond). — Multiple  division  of  an  axis  in  all 
directions  producing  a  witches'-broom-like  arrangement  of  branches. 

Speiranthy  (Ch.  Morren). — The  anomalous  condition  in  which  the 
flowers  develop  into  a  twisted  form. 

Spiroism  (Ch.  Morren).— An  elongated  snail-like  development  of 
an  organ. 

Staminody. — The  transformation  of  a  petal  into  a  stamen. 

Stasimorphy  (Masters). — The  arrest  in  the  development  of  an 
organ,  or  an  organ  complex,  and  the  stoppage  of  development  at  a  lower 
stage. 

Stesomy  (Ch.  Morren). — A  term  with  similar  usage  to  stasimorphy. 

Strophomany  (Schimper).^ — A  term  used  in  the  same  sense  as 
biastrepsis  for  twisting,  or  torsion. 

Suppression. — The  complete  abortion  of  an  organ. 

Synandry.^ — The  abnormal  union  of  stamens. 

Synanthy.^ — Lateral  union  of  two  or  more  flowers.  This  condition 
can  arise  in  a  number  of  ways;  for  example,  by  the  approach  and  fusion 
of  two  floral  fundaments,  or  through  the  partial  forking  of  a  receptacle, 
or  through  floriparous.ecblastesis,  etc. 

Synanthody. — ^Lateral  union  of  two  floral  buds  on  the  same  stalk, 
or  on  two  pedunfles  which  have  become  fasciated. 

Syncarpy.- — ^Lateral  fusion  of  two  or  more  fruits.  This  condition 
is  the  natural  result  of  synanthy. 

Synophthy  (Ch.  Morren). — The  union  of  two  leaf  buds,  or  foliage 
shoots  with  each  other. 

Sjmspermy.^ — The  fusion  of  several  seeds. 

Taxitery  (Gubler). — A  modification  which  is  so  slight  that  it  admits 
of  comparison  with  the  normal  form.     Contrast  Idiotery. 

Torsion. — A  spiral  twisting,  or  bending,  or  parts  or  organs. 

Triplasy  (Fermond). — The  separation  of  an  organ  into  three  analo- 
gous structures.     Trifurcation. 

Virescence. — The  abnormal  development  of  flowers  in  which  all 
organs  are  colored  green  and  more  or  less  wholly  transformed  to  small 
foliage  leaves.  If  the  metamorphosis  is  complete,  there  result  foliage 
leaves  with  distinct  lamina  and  this  condition  is  known  as  frondescence. 

In  concluding  this  glossary  of  teratologic  terms,  it  might  be  well 
to  add  that  a  recent  work  on  plant  teratology  has  appeared.  It  is 
designed  to  bring  our  knowledge  up  to  date.     The  first  volume  of 


340  GENERAL   PLANT   PATHOLOGY 

Worsdell's^  "Principles  of  Plant  Teratology"  includes  a  consideration 
of  the  fungi  and  bryophytes  as  non-vascular  plants  and  with  vascular 
plants  he  goes  as  far  as  a  consideration  of  the  teratology  of  roots,  stems, 
leaves  and  flowers.  It  is  issued  by  the  Ray  Society,  as  was  that  of 
Maxwell  T.  Masters  in  1869. 

^  WoRSDELL,  Wilson    Crosfield:  The  Principles  of   Plant  Teratology,  vol.  i., 
London,  printed  for  the  Ray  Society,  1915;  vol.  ii,  1916. 


CHAPTER  XXVHI 
SYMPTOMS  OF  DISEASE  (SYMPTOMATOLOGY) 

The  preceding  pages  have  dealt  with  the  causes  of  plant  diseases, 
that  is  their  etiology.  It  remains  to  discuss  the  symptoms  of  disease 
as  that  is  a  very  important  matter  in  deciding  as  to  the  nature  of  the 
disease,  and  the  harm  that  the  various  diseases  may  do  to  our  agri- 
cultural crops.  It  is  easy  to  determine  that  there  is  something  wrong 
with  the  plant,  because  such  well-known  symptoms  as  withering, 
as  yellowing,  as  abnormal  growth  are  evidences  of  it,  but  it  is  quite 
another  thing  to  decide  as  to  the  specific  nature  of  the  disease,  its  cause 
and  probable  amelioration.  Even  to  the  trained  plant  pathologist,  it 
is  not  an  easy  problem  to  decide  what  the  trouble  is.  It  requires  some- 
times two  or  three  years  of  research  work  with  all  the  refined  methods 
of  modern  science  to  reach  a  satisfactory  conclusion,  and  at  times  even 
then  the  solution  is  baffling.  To  call  a  pathologist,  or  a  botanist,  an 
ignoramus,  because  he  cannot  by  a  study  of  the  symptoms  name  the  dis- 
ease, is  unworthy  of  people  who  claim  to  be  cultured,  and  yet  it  fre- 
quently happens  that  the  farmer's  opinion  of  the  book  scientist  is  based 
upon  just  such  a  flimsy  pretext.  General  conclusions  are  reached  in 
this  field  of  inquiry,  just  as  in  other  fields,  by  the  process  of  exclusion. 
The  pathologist  puts  questions  to  himself  about  the  plant  and  gradually 
he  eliminates  the  impossible  conditions,  gradually  narrowing  himself 
down  to  a  few  possibilities.  For  example,  he  might  ask  himself 
whether  the  cause  of  the  disease  is  external  or  internal.  If  external, 
then  whether  it  is  due  to  climate,  to  animals,  or  plant  parasites.  If 
plant  parasites  are  concerned,  then  are  they  flowering  plants  or  fungi. 
We  will  suppose  that  he  finds  that  the  disease  is  of  fungal  origin.  Then 
with  the  cultural  means  at  his  disposal,  the  fungus  must  be  obtained 
in  pure  culture,  and  its  pathogenicity  tried  out  upon  healthy  individuals 
corresponding  racially,  or  specifically,  with  the  diseased  ones.  If  the 
inoculation  of  the  healthy  host  is  successful,  then  the  recovery  of  the 
fungus  from  the  tissues  for  comparative  cultural  study  will   follow. 

341 


342  GENERAL    PLANT    PATHOLOGY 

Knowing  the  specific  fungal  organism,  a  great  stride  has  been  made 
toward  a  comprehensive  knowledge  of  the  disease. 

The  plant  pathologist,  who  would  be  successful  in  his  profession, 
must  be  acquainted  with  the  normal,  or  healthy,  conditions  of  plants, 
or  how  can  he  study  the  unhealthy  states?  Any  departure  from  the 
healthy  state  is  indicated  by  a  certain  behavior  of  the  plant,  or  reac- 
tion to  the  causes  of  disease  and  certain  peculiarities  of  structure,  form 
and  color  are  also  manifested.  An  investigation  of  these  character- 
istics of  disease  concerns  symptomatology.  The  most  common  symp- 
toms of  plant  diseases  may  be  classified  according  to  the  outline  pre- 
sented by  Heald  in  Bulletin  135  of  the  University  of  Texas,  Nov.  15, 
1909,  entitled  "Symptoms  of  Diseases  in  Plants." 

1.  Discoloration  or  change  of  color  from  the  normal. 

(a)  Pallor.     Yellowish  or  white  instead  of  the  normal  green. 

(b)  Colored  spots  or  areas  on  leaves  or  stems. 
Whitish  or  gray:  mildews;  white  rusts,  etc. 
Yellow:  many  leaf  spots. 

Red  or  orange:  rusts,  leaf  spots,  etc. 
Brown:  many  leaf  spots. 
Black:  black  rust,  tar  spots,  etc. 
Variegated:  leaf  spots,  etc. 

2.  Shot-hole:  perforation  of  leaves. 

3.  Wilting:  "damping-off,"  "wilt,"  etc. 

4.  Necrosis:  death  of  parts,  as  leaves,  twigs,  stems,  etc. 

5.  Reduction  in  size:  dwarfing  or  atrophy. 

6.  Increase  in  size:  hypertrophy. 

7.  Replacement  of  organs  by  a  new  structure. 

8.  Mummification. 

9.  Change  of  position. 

10.  Destruction  of  organs. 

1 1 .  Excrescences  and  malformations. 

Galls:  pustules,  tumors,  corky  outgrowths,  crown  galls,  etc. 
Cankers:  malformations  in  the  bark  generally  resulting  in  an  open 

wound. 
Punks  or  conchs  and  other  fruits  of  fleshy  fungi.    . 
Witches'  brooms. 
Rosettes  and  hairy  root. 


SYMPTOMS    OF    DISEASE    (SYMPTOMATOLOGY)  343 

12.  Exudations. 
Slime  flux. 

Gummosis:  especially  for  stone  fruits. 
Resinosis:  especially  for  coniferous  trees. 

13.  Rotting: 

Dry  rot  and  soft  rot:  "the  gangrene"  of  plant  tissue. 

Root  rots:  alfalfa,  cotton,  beets,  cherry,  etc.,  generally  woody  or 
fleshy  roots. 

Stem  or  trunk:  dry  rot  of  trees;  rot  of  modified  stems  like  rhi- 
zomes, bulbs,  or  tubers.  > 

Buds. 

Fruits:  fleshy  fruits  of  various  kinds. 

It  will  be  profitable  to  discuss  the  symptoms  of  disease  under  the 
above  heads. 

I.  Discolor ations. — ^The  unnatural,  or  false  color  which  plants 
assume  under  diseased  conditions  may  be  included  under  the  head  of 
discolorations.  Sometimes,  as  in  woods,  the  discoloration  may  appear 
as  a  stain.  AbnormaUty  of  color  usua|y  accompanies  other  symptoms 
of  plant  disease.  Pallor,  or  chlorosis,  v^ere  the  plant  assumes  a  yellow- 
ish to  white,  or  sickly-pale  hue,  is  due  to  a  number  of  causes.  Promi- 
nently, one  form  is  due  to  the  absence  of  light,  whereby  the  plant  be- 
comes etiolated,  or  suffers  etiolation.  It  is  considered  that  the  laying  of 
wheat  and  other  cereals  is  one  form  of  this  etiolation  where,  through 
lack  of  carbohydrates,  the  cellulose  which  forms  the  strengthening  of  the 
cell  wall  does  not  form  properly.;;,' Sometimes  the  gardener  induces 
etiolation  in  his  celery,  endive  and  asparagus  plants,  where  the  blanch- 
ing is  secured  by  covering  such  plants  with  soil.  True  chlorosis  is  due 
to  an  enzyme  which  destroys  the  chlorophyll  pigment  of  the  chloroplasts 
which  are  fully  developed.  Icterus  is  the  condition  where  the  organs 
are  only  yellow;  chlorosis,  where  they  are  white,  such  as  in  the  mosaic, 
or  calico  disease  of  plants  formerly  described.  Yellowing  may  be  in- 
duced experimentally  by  an  excess  of  carbon  dioxide,  in  fact  yellowing 
accompanies  wilting,  the  attack  of  wire  worms,  the  presence  of  poisons, 
or  acid  gases. 

Variegation  and  albinism  may  be  apparently  normal  conditions  of 
some  varieties  of  plants,  for  gardeners  and  horticulturists  grow  such 
plants  by  preference  for  decorative  uses.     This  variegation,  or  albinism, 


344 


GENERAL   PLANT   PATHOLOGY 


is  induced  in  all  probability  by  the  presence  of  oxidizing  enzymes  in 
patches  of  cells  where  the  chlorophyll  pigment  is  destroyed  and  not  in 
other  adjoining  areas. 

The  formation  of  spots  on  leaves  (Fig.  134),  stems,  flowers,  or  fruits  is 
due  to  a  variety  of  causes.  The  grayish  or  whitish  spots  on  the  under 
surface  of  grape  leaves  are  due  to  mildews,  on  the  stems  of  cruciferous 
plants  to  white  rusts  and  on  the  leaves  of  the  parsnip  are  found  white 
spots  due  to  a  fungus,  Cercospordla.    Grayish  spots  on  the  prickly  pear 


Fig.  134. — Apple  leaves  showing  leaf  spots  produced  by  natural  infection  with 
Sphaeropsis  malorum.  {After  Scott,  W.  M.,  and  Rorer,  J.  B.,  Bull.  121,  U.  S.  Bureau 
of  Plant  Industry,  1908.) 

and  on  the  leaves  of  the  box  trees  are  occasioned  by  a  disease  known  as 
anthracnose.  Many  leaf  spots  are  yellow  as  in  violets,  oaks,  cucumbers 
and  melons.  The  red  or  orange  spots  on  plants  usually  suggest  the 
presence  of  rusts  as  on  wheat,  rye,  alfalfa  and  a  host  of  other  cultivated 
and  wild  plants.  The  so-called  tar  spots  of  the  maple  leaves  are  bla'gk 
in  color  and  such  discolorations  of  the  leaf  surface  are  traceable  to  the 
attack  of  a  fungus,  Rhytisma  acerinum.  Apples  are  frequently  marked 
by  fly  specks  which  are  usually  clustered  as  small  circular  black  spots.. 
A  fungus  is  the  causal  agent. 


SYMPTOMS    OF   DISEASE    (SYMPTOMATOLOGY) 


345 


2.  Shot-holes  (Fig.  135). — The  perforations  of  leaves  and  the  forma- 
tion of  what  are  called  shot-holes  illustrate  another  form  of  fungous 
attack,  where  circular  patches  of  dead  tissue  killed  by  the  fungus  drop 
out  leaving  a  hole.  The  Enghsh  morello  cherry  trees  in  some  sections 
of  our  country  have  been  killed  during  the  past  few  years  by  this  "  shot- 


FlG.    135. — Shot-hole    disease    of    the    plum    due  to  Cylindrosporium 

Heald,  F.  D.,  Bull.  135  {Sci.  Ser.  14),  Univ.  of  Tex.,  Nov.  15,  1909.) 


{.After 


hole"  disease.  When  the  funguses  belonging  to  the  genera  Cercospora 
and  Phyllostida  attack  the  leaves  of  Virginia  creeper  perforations  may 
be  formed. 

3.  Wilting. — Wilting  in  general  is  due  to  the  lack  of  sufficient  water 
to  supply  that  lost  by  transpiration,  for  wherever  the  amount  of  water 


346  GENERAL    PLANT    PATHOLOGY 

transpired  exceeds  that  absorbed  by  the  roots  wilting  occurs.  Wilting 
may  result,  if  the  normal  ascent  of  the  sap  is  interfered  with  by  the 
growth  of  fungi  into  the  water-conducting  tissues,  the  entrance  of  bac- 
teria into  the  woody  vessels  of  the  plant,  whereby  they  are  literally 
plugged  with  such  organisms,  or  some  injury  which  cuts  off  the  ascend- 
ing current  of  water.  Damping-off  is  a  form  of- wilt  in  which  an  oomy- 
cetous  fungus  enters  the  collar  of  seedling  plants,  or  where  a  Rhizoctonia 
species  invests  the  roots  of  the  growing  plants  and  interferes  with  the 
regular  water  absorptive  processes. 

4.  iVecro5M.— Necrosis  is  the  mortification,  or  death,  of  the  tissues. 
The  term  is  usually  applied  to  the  death,  or  loss  of  vitality,  of  one  part  of 
a  plant,  while  the  other  parts  remain  alive.  When  the  fungus,  Fusa- 
rium  trichothecoides ,  is  inoculated  into  Green  Mountain  potato  tubers, 
in  about  three  weeks'  time  it  will  be  found  that  a  portion  of  the  tuber, 
usually  the  central  part  directly  beneath  the  point  of  inoculation,  has 
undergone  necrosis.  The  surface  of  the  potato  tuber  becomes  sunken 
through  the  death  and  collapse  of  the  starch  containing  cells  and  the 
lesions  may  involve  half  of  the  tuber.  The  black  rot  of  the  navel 
orange  is  due  to  a  fungus,  AUernaria  citri,  which  gains  entrance  to  the 
fruit  through  slight  imperfections  about  the  navel  end.  A  black 
decayed  area  is  found  under  the  skin.  This  decay  does  not  spread  im- 
mediately through  the  entire  fruit,  but  remains  for  weeks- as  a  small 
black  necrotic  area  with  a  mass  of  the  fungus  present.  The  decayed  tis- 
sue does  not  always  extend  to  the  surface,  but  remains  beneath  the  skin. 
Necrosis  often  follows  the  action  of  frost  in  killing  the  cortex  cells  of 
fruit  trees  in  patches  with  a  blackening  of  the  tissues.  Fire  bhght  may 
be  the  cause  of  necrosis,  for  the  cambium  which  is  killed  dries  up  in 
black  patches. 

5.  Dwarfing. — A  reduction  in  the  size  of  a  plant  is  very  often  asso- 
ciated with  disease.  This  may  be  true  of  the  whole  plant,  or  some 
particular  organ  only  may  be  dwarfed.  Apples  are  frequently  reduced 
in  size  by  the  attack  of  the  scab  fungus,  sometimes  not  reaching  one- 
fourth  the  size,  and  the  same  is  true  of  apples  affected  by  the  cedar  rust. 
Dwarfing  of  the  whole  plant  may  be  a  symptom  of  malnutrition.  It 
may  be  evidence  of  a  poor  soil,  or  the  repeated  maiming,  or  nipping  off  of 
the  buds  by  cattle,  or  purposely  by  man,  as  is  the  case  with  the  minia- 
ture trees  of  the  Japanese.  Dwarfing,  or  nanism,  may  be  the  result 
of  climate,  as  is  the  normal  case  with  alpine  plants.     Prostrate  forms  of 


SYMPTOMS    OF    DISEASE    (SYMPTOMATOLOGY) 


347 


trees  of  great  age  are  formed  by  the  action  of  the  dimate  of  high 
mountains,  or  by  growth  in  porous  sand  on  exposed  sea  dunes.  Atro- 
phy, or  the  non-formation  of  parts,  or  organs,  is  a  phase  of  dwarfing. 
It  is  seen  in  the  dwindling  of  organs  in  size,  as  the  result  of  various 
causes,  such  as  the  attack  of  fungi.  The  carpels  of  Anemone  are 
atrophied  in  plants  infested  by  Mcidium  and  the  whole  flower  is  sup- 
pressed when  the  cherry  is  attacked  by  Ex- 
oasciis  cerasi.  Exoascus  pruni  is  responsible 
for  the  absence  of  the  stone  in  plum  fruits,  etc. 

6.  Hypertrophy. — The  undue  excessive  de- 
velopment of  a  plant  part  is  a  symptom  of  a 
diseased  condition  of  that  part.  The  bladder 
plums  formed  in  the  plum  pocket  disease  are 
good  illustrations  of  hypertrophied  tissues,  as 
the  replacement  of  the  rye  ovary  by  the  ergot 
sclerotium,  following  the  entrance  of  the  spores 
of  Clamceps  purpurea.  The  attack  of  Gym- 
nosporangium  biseptatum  (Fig.  136)  results  in 
the  massive  enlargement  of  the  stem  of  the 
white  cedar.  A  rust  fungus  is  responsible  for 
the  increase  in  size  of  the  twigs  and  petioles  of 
our  common  ash  and  elder. 

7.  Replacement: — ^A  new  structure  takes 
the  place  of  organs. 

8.  M ummifi cation. — The  drying  and 
wrinkling  of  fruits  and  other  plant  parts 
where  the  general  shape  of  the  part  is  pre- 
served, but  in  a  reduced  size,  is  an  evidence 
of  the  unhealthy  condition  of  that  organ,  or 
part.  The  attack  of  the  black-rot  fungus, 
Sphceropsis  malorum,  brings  about  a  slow  desiccation  of  the  fruit  which 
may  remain  hanging  on  the  tree  over  winter  and  in  a  shriveled  condi- 
tion. Frequently,  the  mummies  produce  a  crop  of  spores,  which  spread 
the  disease. 

9.  Alteration  of  Position. — The  change  of  position  of  an  organ  from 
its  normal  one'is  a  sure  symptom  of  disease,  usually  the  attack  of  some 
fungous  parasite.  The  normal  position  of  the  leaves  of  the  house  leek, 
Sempervivum  tectorum,  is  that  of  a  rosette  with  the  spirally  arranged 


Fig.  136. — Swelling  of 
main  stem  of  white  cedar 
caused  by  Gymnosporangium 
biseptatum.  (After  Harsh- 
berger,  Proc.  Acad.  Nat.  Set., 
Phila.,  May,  1902.) 


348  GENERAL   PLANT   PATHOLOGY 

leaves  approximately  horizontal.  When  attacked  by  a  rust  fungus, 
Endophyllum  sempervivi  (Fig.  137),  the  diseased  leaves  grow  erect. 
The  same  is  true  with  our  native  American  hepatica,  Hepatica  triloba. 
Infrequently,  it  is  attacked  by  a  rust  fungus  in  the  aecial  condition, 
Tranzschelia  punctata,  so  that  (Fig.  138),  the  rusted  leaves  develop  a 
larger,  stiffer  petiole,  stand  erect  .with  a  smaller,  stifYer  leaf  blade  on 
which  the  aecia  are  found.  The  common  garden  purslane  Portiilaca 
oleracea,  usually  grows  in  a  prostrate  position,  but  when  attacked  by 
the  white  rust,  Cystopus  (Albugo)  portulacce,  many  of  the  diseased 
branches  become  erect  or  ascending.  The  stems  of  Vaccinium  vitis- 
idcBa  become  erect  the  second  year  after  infection  by  Melampsora 
Goeppertiana. 


Fig.  137. — Two  plants  of  house-leek,  Sempervivum.  Left  one  affected  by  Endo- 
phyllum sempervivi.  Right  one,  a  healthy  plant.  {After  Grove,  W.  B.:  The  Brilish 
Rusl  Fungi,  1913:  54. 

10.  Destruction  of  Organs. — The  destruction  of  plant  organs  by  the 
attack  of  fungi  is  well  illustrated  by  the  cereal  smuts,  which  attack  the 
flower  parts  reducing  them  to  a  black  powdery  mass  of  spores,  which  are 
carried  away,  leaving  nothing  but  the  bare  axis  on  which  the  flowers 
were  originally  situated. 

11.  Excrescences  and  Malformations. — These  will  be  treated  of  in 
detail  in  another  chapter.  Here  it  may  be  said  that  galls,  pustules, 
tumors,  corky  outgrowths,  crown  galls,  cankers,  burls,  or  knauers, 
(Fig.  139)  witches'  brooms  (Fig.  140),  etc.,  are  evidences  of  diseased 
conditions.  The  nature  of  these  excrescences  and  malformations  can- 
not be  discussed  here,  but  it  may  be  said  that  they  are  specific  and 
usually  associated  with  the  attack  of  some  fungus,  as  for  example  the 
plum  knot  due  to  Plowrightia  morbosa,  the  cedar  apples  formed  on  the 


SYMPTOMS    OF   DISEASE    (SYMPTOMATOLOGY)  349 


Fig.  138. — Hepatica  triloba  parasitized  by  a  rust  fungus,  Tranzschelia  punctata, 
which  causes  some  of  the  leaves  to  stiffen  and  grow  erect.  Left  figure  shows  ascia, 
April  29,  1915. 


35° 


GENERAL   PLANT    PATHOLOGY 


red  cedar  by  Gymnosporangimn  juniperi-virginiatKE.  The  crown  galls, 
or  possible  vegetal  caricers,  are  another  illustration  of  such  excres- 
cences, while  malformations  are  represented  by  peach  leaf  curl  and 
the  witches'  brooms  on  trees. 

12.  Exudations. — The  formation  of  slimy  substances,  which  flow 
from  trees  and  plants,  the  diseased  conditions  known  as  bacteriosis, 
gummosis^  and  resinosis,  illustrate  the  character  of  the  exudations  from 


Fig.  139. 


-Burl,  or  enlarged  base  of  an  oak  tree  in  the  forest  on  Gardiner's  Island, 
New  York,  July  17,  1915. 


plants  under  abnormal  conditions.  The  production  of  clear  amber- 
colored  secretions,  which  accumulate  on  the  surface  of  the  diseased  parts, 
is  known  as  gummosis  and  is  seen  in  cherries,  apricots,  almonds  and 
many  other  trees.  It  follows  wounds  or  the  attack  of  fungi.  The 
same  condition  in  coniferous  trees  is  known  as  resinosis  and  in  a  few 
trees  it  is  of  economic  interest  because,  as  in  the  spruce,  the  exudation  of 

1  Wolf,  Frederick  A.:  Gummosis.     The  Plant  World,  15:  49-59,  March,  191 2. 
Butler,  O.:  A  Study  on  Gummosis  of  Prmiits  and  Citrus.     Annals  of  Botany, 
25:  107-153,  1910- 


SYMPTOMS    OF    DISEASE    (SYMPTOMATOLOGY)  35 1 


Fig.    140. — Branch-knot  or  witches'-broom  of  the  Hackberry  ,(C>//J5  occidentalis) . 
{After  Kellerman,  W.  A.,  Mycological  Bulletin,  Nos.  61-72,  July,  1906. 


352 


GENERAL   PLANT    PATHOLOGY 


gum  rosin  known  as  ''spruce  gum"  is  collected  and  sold  at  from  two 
dollars  to  two  dollars  and  fifty  cents  a  pound.  ^  Where  due  to  the  attack 
of  bacteria  it  is  called  bacteriosis.  Tumescence  is  the  over-turgescence 
of  plant  tissues  due  to  the  excess  of  water.  It  sometimes  indicates 
pathologic  changes  and  was  formerly  called  (edema,  or  dropsy.  Flux 
is  another  name  applied  to  the  issuance  of  fluids  from  wounds  in  trees, 
while  slime  flux  issuing  from  wounds  may  be  frothy,  owing  to  the  fer- 
mentative activity  of  yeasts  and  other  fungi,  which  live  in  such  slimes. 
Manna  flux  is  found  in  such  trees  as  the  manna  ash  and  species  of 
tamarisk.     Cuckoo  spit  is  a  frothy   material  found  on   grasses  and 


■  g 

'1 

"M 

1 

1 

1 

'"'i 

P 

7 

1 

Fig.   141. — Crown  gall  with  hairy  root  on  nursery  stock  of   Northern  Spy  apple. 
-  {From  Marshall  after  Paddock.) 

other  plants  in  which  green  sucking  insects  live.  Honey-dew  is  the 
excretion  of  plant  lice,  or  aphides,  and  its  presence  encourages  the 
growth  of  fungi  {Meliola,  Scorias). 

13.  Rotting. — Rottenness  of  plant  parts  is  the  state  of  decomposition 
putrefaction,  or  decay  usually  associated  with  the  formation  of 
malodorous,  or  putrid  substances.  Several  kinds  of  rots  are  dis- 
tinguished as  dry  rot,  soft  rot,  black  rot  and  gangrene.  Usually  such 
rot  or  gangrene  is  due  to  the  presence  of  some  bacterial,  or  fungous 
organism,  which  brings  about  the  decomposition  of  the  parts  attacked. 
The  decay  may  be  slow,  or  rapid.  Sometimes  the  rot  is  associated  with 
the  production  of  bitter  substances,  as  in  the  bitter  rot  of  apples. 
^  Record,  Samuel  J. :  Harvesting  the  Spruce-gum  Crop.  Tlie  Country  Gentle- 
man, Feb.  26,  1916,  p.  475. 


SYMPTOMS    OF   DISEASE    (SYMPTOMATOLOGY)  353 

The  wet  rot  of  potatoes  is  probably  due  to  putrefactive  bacteria.  The 
tissues  become  soft,  then  mushy,  and  finally  become  a  liquid  mass  with 
a  vile  smell. 

BIBLIOGRAPHY  OF  PLANT  DISEASES  IN  GENERAL 

Heald,  Frederick  D.:  Symptoms  of  Disease  in  Plants.     Bull.  135,  University  of 

Texas,  Nov.  15,  1909. 
Klebahn,   Prof.  Dr.  H.:    Grundziige    der    allgemeinen    Phytopathologie.     Berlin 

Gebriider  Borntraeger,  191 2. 
KtJSTER,  Dr.  Ern.st:  Pathologische  Pflanzenanatomie.     Gustav  Fischer  in  Jena, 

1903,  Zweite  Auflage,  1916. 
KtJSTER,   Dr.    Ernst:  Pathological   Plant   Anatomy.     Authorized    translation   by 

Frances  Dorrance,  1913-1915. 
Smith,  John  B.:  Economic  Entomology  for  the  Farmer  and  Fruit  Grower,  and  for 

Use  as  a  Text-book  in  Agricultural  Schools  and  Colleges,  J.  B.  Lippincott  Co., 

1896. 
Stengel,  Alfred:  A  Text-book  of  Pathology,  W.  B.  Saunders  Co.,  Philadelphia, 

1906. 
Ward,  H.  Marshall:  Disease  in  Plants,  Macmillan  Co.,  &  1901. 


23 


CHAPTER  XXIX 
PATHOLOGIC  PLANT  ANATOMY 

With  the  multiplicity  of  higher  plant  forms,  in  which  the  same  end 
is  attained  in  a  diversity  of  ways,  the  terms  normal  and  abnormal 
become  in  one  sense  merely  relative  terms  for  what  apparently  is  the 
normal  method  of  procedure  in  one  group  of  plants,  may  be  decidedly 
different,  or  abnormal,  in  other  uncommon  groups.  The  words  normal 
and  abnormal  are,  therefore,  variable  terms,  but  useful  ones.  Speci- 
fically, when  we  use  the  word  abnormal,  we  mean  the  departure,  or 
deviation,  from  the  normal  (average)  structure  or  function  of  the  mem- 
bers of  any  group  selected  for  investigation.  Pathologic  plant  anatomy, 
therefore,  has  to  deal  with  abnormal,  but  not  necessarily  diseased 
organs,  and  yet  a  study  of  diseased  tissues  is  an  important  subject  of 
investigation  for  the  plant  pathologist. 

The  material  which  forms  the  substance  of  our  inquiry  naturally 
falls  into  two  principal  groups. 

1.  The  differentiation,  number  or  size  of  the  cells  of  pathologic 
tissues  remain  more  or  less  below  the  normal,  so  that  the  tissues  in  one 
or  more  ways  remain  in  a  stage  of  incomplete  development.  The  term 
Hypoplasia  designates  those  abnormal  processes  of  formation,  which 
compared  with  the  corresponding  normal  processes  of  development 
appear  retarded  as  it  were  and  prematurely. 

2.  The  pathologic  cells  and  tissues  exceed  the  conditions  of  differen- 
tiation and  growth  characteristic  of  normal  plants,  so  that  a  treatment 
of  such  necessitates  a  consideration  of  several  independent  groups. 

(a)  The  abnormal  cells  differ  from  the  normal  ones  only  in  their 
internal  structure  (contents,  mechanics,  etc.)  and  for  the  processes  of 
differentiation  by  which  the  tissue  cells  supplement  their  normal 
qualities,  or  exchange  them  for  new  ones,  the  term  Metaplasia  is 
used. 

(6)  The  increase  in  size  of  abnormal  cells  over  normal  ones  is 
termed  Hypertrophy  (v-rrep  =  over,  excessive;  rpepoi  =  to  nourish), 
and  it  is  not  important  fundamentally  whether  the  histologic  structure 

354 


PATHOLOGIC   PLANT   ANATOMY  355 

of  the  cells  concerned  remains  similar  to  that  of  the  normal  ones,  or  is 
altered  in  some  way. 

(c)  The  increase  of  a  part  by  an  increase  in  the  number  of  its  indi- 
vidual structural  elements  is  known  as  Hyperplasia  (wep  =  over, 
excessive;  TrXoo-ts  =  formation,  structure),  and  this  depends  on  cell 
division  following  cell  growth.  A  large  number  of  abnormal  formations 
arise  through  hyperplasia  and  the  histology  of  the  newly  formed  tissues 
is  exceedingly  varied. 

3.  The  processes  of  Restitution  consist  in  the  restoration  of 
structures,  which  resemble  those  lost  in  injuries  and  mutilations  of  the 
plant  body.  Although  the  tissues  thus  formed  are  like  the  normal 
ones  yet  their  formation  following  injuries,  or  mutilations,  comes  within 
the  realm  of  pathologic  anatomy. 

Hence  we  shall  treat  of  morbid  anatomy  under  the  five  heads 
suggested  in  the  above  considerations.  Naturally  the  material  for 
our  investigation  and  treatment  arranges  itself  into  five  chapters,  on 
"Restitution,"  "Hypoplasia,"  "Metaplasia,"  "Hypertrophy"  and 
"Hyperplasia." 

RESTITUTION 

Following  a  wound  or  other  injury  or  the  removal  of  a  plant  part, 
the  organs  are  stimulated  to  renew  the  lost  part,  or  to  repair  the  damage 
to  the  cells  or  tissues.  The  regeneration  of  lost  or  injured  plant  cells, 
tissues,  or  organs,  is  called  specifically  in  pathologic  plant  anatomy 
restitution,  wHile  the  word  regeneration,  although  implying  restitution 
(L.  restitutio  (-n),  <  restitutus,  pp.  of  restituo,  restore,  <  re-,  again,  + 
statuo,  set  up,  <  sto,  stand),  is  used  in  a  somewhat  different  sense. 

The  process  of  restitution,  it  is  conceivable,  includes  a  number  of 
distinct  operations.^  The  newly  formed  parts  are  formed  at  the  place 
of  amputation  and  are  like  the  lost  portion  (as  the  regeneration  of  root 
tips)  or  the  newly  formed  parts,  which  resemble  the  lost  ones,  are  not 
produced  at  the  injured  place,  but  some  distance  away  from  it,  or  the 
new  parts  arise  on  the  cut  surface,  but  are  unlike  the  lost  part  (hetero- 
morphosis),  and  finally  the  new  parts  do  not  resemble  the  lost  ones,  nor 
do  they  arise  at  the  surface  of  the  amputation. 

It  will  be  profitable  to  discuss  the  two  most  important  forms  of 

*  Consult  Studien  iiber  die  Regeneration  v.  Professor  Dr.  B.  N^mec.  Mit  18 
Textabb. 


356  GENERAL   PLANT    PATHOLOGY 

restitution,  viz.,  that  of  the  cell  and  that  of  the  tissues.  The  experi- 
ments of  Tittman  have  shown  that  the  waxy  cuticle  of  the  castor-oil 
plant,  Ricinus  communis,  may  be  restored  after  removal.  Exposure 
of  the  protoplast  results  in  many  cases  in  the  formation  of  a  new  cell 
membrane,  as  is  illustrated  in  some  of  the  large-celled  algae  belonging  to 
the  Siphoned.  Frequently,  it  is  possible  to  demonstrate  the  restitu- 
tion of  the  cell  membrane  by  the  process  of  plasmolysis  in  which  the 
protoplasm  is  made  to  retreat  from  the  cell  wall.  The  time  varies  for 
its  formation  under  conditions  of  plasmolysis.  In  Conferva,  it  takes 
place  in  one  to  two  days,  in  Zygnema  in  three  to  four  days.  When  the 
root  hairs  of  dicotyledonous  plants  are  plasmolyzed  new  membranes 
are  formed  about  the  protoplast. 

Wounded  siphonaceous  algal  cells  {Caulerpa,  Valonia,  Vaucheria), 
where  the  cell  wall  has  been  injured,  are  capable  of  restoring  the  cell 
wall.  Some  fungi  show  such  restitution  also,  while  the  injured  cells 
of  the  higher  plants  lack  this  power.  A  few  exceptions  are  known  where 
nettle  hairs  of  Urtica  dioica  may  imperfectly  replace  the  broken-off  tip. 
Pricking  the  turgid  cell  of  Valonia  utricularis,  as  I  have  done  with 
fresh  specimens  in  Bermuda,  is  followed  by  the  escape  of  a  liquid  jet 
and  later  the  opening  is  closed  by  a  gall-like,  protoplasmic,  chloro- 
phylless  plug. 

It  has  been  demonstrated  that  the  important  cell  wall  can  be  regen- 
erated on  fragments  of  protoplasm  provided  the  influence  of  the  nucleus 
is  felt  in  such  formation.  Klebs  has  shown  that,  with  the  removal  of 
the  nucleus  from  the  cell,  that  cell  has  lost  all  its  power  to  produce  new 
cell  walls,  but  a  distant  nucleus  may  extend  its  wall-forming  influence, 
when  removed  several  millimeters  away  in  an  adjoining  cell. 

In  the  restitution  of  tissues,  we  will  consider  those  cases  in  which  the 
injured  cells  remain  unhealed,  but  in  which  the  uninjured  neighboring 
cells  bring  about  the  restitution.  The  removal  of  the  rhizoidal  hairs 
on  the  thallus  of  Marchantia  is  followed  by  the  appearance  of  other 
hairs  in  a  few  days,  which  may  grow  out  through  the  cavity  of  the 
mutilated  one  as  described  so  carefully  by  King.  The  mutilated 
tip,  or  growing  point,  of  many  multicellular  algae  is  replaced  by  the 
development  of  the  uppermost  intact  cell.  Brefeld  found  in  the 
sclerotia  of  Coprinus  stercorarius  the  inner  cells  are  able  to  regenerate 
the  outer  black  cuticularized  coat,  if  that  is  removed. 

The  number  of  cases  of  tissue  restitution  known  in  the  higher  plants 


PATHOLOGIC   PLANT   ANATOMY  357 

are  few.  The  peridium,  or  secondary  tegumentary  tissue  of  stem  or 
root,  is  easily  regenerated,  as  is  seen  in  the  formation  of  new  cork  layers 
in  the  cork  oak  after  the  removal  of  older  ones.  The  epidermis  is  not 
always  replaced  but  Massart  found  that  removal  of  the  epidermis  of 
Lysimachia  vulgaris  resulted  in  the  regeneration  of  a  new  hair-bearing 
epidermis.  The  regeneration  of  the  vascular  bundles  has  been  studied 
in  monocotyledonous  plants  and  in  dicotyledons.  The  regeneration 
of  roots  in  monocotyledons  consists  in  the  replacement  of  epidermis, 
phloem  and  xylem.  In  dicotyledons  before  the  wood  and  bast  are 
replaced  there  is  a  regeneration  of  the  endodermis,  so  that  the  restora- 
tion of  central  cylinders,  that  have  been  destroyed,  is  not  unusual. 

HYPOPLASIA 

The  condition  of  hypoplasia  in  plants  is  one  of  arrested  develop- 
ments. The  organism,  or  one  of  its  parts,  does  not  reach  normal  devel- 
opment, but  that  development  is  arrested,  or  stopped  prematurely. 
Hypoplasia  is,  therefore,  defective  development.  The  plant  morpholo- 
gists  and  plant  anatomists  are  chiefly  concerned  with  the  problems 
of  arrested  development  and  recently  awakened  interest  has  been 
taken  in  its  study,  because  it  has  been  found  that  the  interpretation  of 
certain  phenomena  is  subject  to  experimental  treatment,  and  hence, 
there  has  arisen  a  coterie  of  experimental  plant  morphologists.  Such 
investigators  have  found  that  the  processes  of  growth  and  differentia- 
tion are  not  always  equally  arrested,  which  are  associated  in  time  and 
place  in  the  normal  course  of  development.  For  example,  leaves  differ 
from  the  normal  by  their  small  size.  They  may  be  retarded  in  their 
form,  as  the  narrow  leaves  of  Sagittaria  produced  under  water,  or  the 
form  may  remain  entirely  undeveloped.  We  will  treat  of  hypoplasia  as 
to  the  number  of  cells,  as  to  the  size  of  the  cells,  as  to  the  differentiation 
of  the  cells  and  the  tissues. 

A.  Number  of  Cells. — It  has  been  found  in  a  study  of  the  dwarf 
forms  of  plants  such  as  occur  on  high  mountain  tops  that  the  condition 
of  nanism  is  not  so  much  due  to  a  decrease  in  the  size  of  the  cells  over 
those  of  the  normal  plant,  but  is  chiefly  conditioned  on  a  reduction  in  the 
number  of  cells.  The  internodes  of  plants  may  be  shortened,  the  size 
of  the  leaf  blade  may  be  reduced,  the  thickness  in  the  leaf  may  be  re- 
duced, and  this  reduction  in  size  is  usually  associated  with  a  loss  in  the 


358  •        GENERAL   PLANT   PATHOLOGY 

number  of  cells,  as  for  example,  the  omission  of  one  of  the  palisade 
layers  of  the  leaf.  External  factors  are  important  in  determining  the 
structure  of  the  leaf  tissue,  for  the  leaf  more  than  any  other  plant 
organ  is  an  index  of  the  influence  of  climate.  This  fact  is  empha- 
sized by  a  work  entirely  devoted  to  this  subject  and  given  the 
appropriate  title  of  "Phyllobiologie."  There  is  a  marked  difference 
in  the  thickness  of  beech  leaves,  for  example,  which  have  developed 
under  different  environmental  conditions,  as  I  have  proved  satisfacto- 
rily by  the  use  of  calipers  and  microscopic  measurements,  which  show 
an  accurate  coincidence.  The  thickness,  or  thinness,  of  such  a  leaf  de- 
pends essentially  on  the  number  of  rows  of  cells.  The  thickest  leaves 
with  the  largest  number  of  palisade  layers  which  I  have  studied,  grew 
in  the  bright  sunlight  in  exposed  places  along  the  edge  of  a  salt  marsh 
at  Cold  Spring  Harbor,  Long  Island.  Sun  leaves  back  from  the  influ- 
ence of  salt  water  were  thinner  and  broader,  while  those,  growing  in 
the  dense  shade  of  the  forest  in  an  inland  situation  near  Philadelphia 
were  the  broadest  and  thinnest  of  all.  Not  only  was  the  mesophyll 
modified  in  these  leaves,  but  a  marked  difference  was  found  in  the  shape 
of  the  epidermal  cells  in  the  sun  and  shade  leaves. 

The  number  of  cells  which  arise  from  the  cambial  layer  suffers  a 
marked  diminution  in  trees  which  grow  under  unfavorable  climatic  life 
conditions.  Drought,  strong  winds,  pressure,  unfavorable  light  and 
nutrition  are  disturbing  factors.  Growth  activity  of  the  cambium  may 
cease  entirely,  if  these  factors  become  too  intensive.  Huntington  has 
proved  abundantly  by  his  study  of  yellow  pines  of  New  Mexico  and 
the  big  trees  of  California  that  climatic  cycles  of  wet  and  arid  conditions 
in  the  past  history  of  North  America  can  be  determined  from  a  study  of 
the  size  and  character  of  the  annual  rings  due  to  the  cambial  activity  of 
those  trees,  and  he  has  plotted  curves  showing  this  relationship  for  a 
period  approximately  3500  years  in  the  case  of  the  big  tree.  Sequoia 
gigantea} 

B.  Size  of  Cells. — The  size  of  ceUs  must  be  considered  also  in  dis- 
cussing the  phenomena  of  hypoplasia.  Abnormally  small  cells  may 
be  produced  in  different  ways:  A  fresh  division  of  the  cells  may  take 
place  before  the  cells  have  reached  the  average  size  which  they  as- 
sume under  normal  conditions.     Klebs  recites  a  case  where  he  culti- 

1  Huntington  Ellsworth:  The  Climatic  Factor.  Publ.  192,  Carnegie  Institu- 
tion of  Washington,  1914:  153. 


PATHOLOGIC   PLANT   ANATOMY  359 

vated  Euaslrum  verrucosum,  a  desmidiaceous  alga,  in  lo  per  cent,  cane 
sugar.  The  daughter  cells  formed  by  a  previous  division  of  those 
cells  divided  again  before  they  had  attained  their  normal  size.  The 
conditions  in  the  higher  plants  where  hypoplasia  is  shown  by  the 
production  of  abnormally  small  cells  are  such  that  the  period  of  elon- 
gation, which  normally  follows  the  last  cell  division,  does  not  take 
place,  or  is  stopped  part  way.  Abnormally  narrow  tracheal  tubes  are 
found  in  dwarfs,  in  etiolated  and  poorly  nourished  plants,  or  in  in- 
dividuals infected  by  fungi,  or  gall-producing  animals.  Disturbances 
in  nutrition  reduce  the  size  of  the  wood  elements  produced  by  cambial 
activity. 

In  the  study  of  the  differentiation  of  cells  and  tissues,  those  cases 
should  be  considered  first  which  concern  the  individual  cells,  where  the 
formative  process  may  stop  prematurely.  An  investigation  of  Udotea 
Desfontainii  shows  the  arresting  action  of  unfavorable  life  conditions 
upon  the  development  of  the  cell  form.  The  leaf-like  part  of  this  alga 
is  composed  of  elongated  sacs,  which  run  lengthwise  and  parallel,  with 
numerous  side  branches  of  limited  growth,  which  interlock  to  give 
the  thallus  its  characteristic  firmness.  If  artificially  cultivated,  the 
parallel  sacs  show  undiminished  growth  activity,  but  the  side  branches 
no  longer  show  limited  growth,  but  unlimited,  and  the  thallus  loses  its 
wonted  form. 

Arrestment  of  the  development  of  the  cell  wall  is  indicated  in  the  par- 
tial, or  entire  cessation  of  the  secondary  growth  in  thickness,  and  as  a 
result,  the  elements  normally  thick-walled  have  walls  of  only  moder- 
ate thickness.  Weak,  or  insufficient,  transpiration  acts  pari  passu  in  a 
poor  development  of  the  cuticle  of  epidermal  cells.  Dwarfed  plants 
frequently  show  weakly  developed  cell  membranes,  as  a  sign  of  disturb- 
ances in  the  nutritive  processes.  Chemic  changes  may  be  associated 
with  hypoplasia.  Lignification  is  rarely  excluded  in  the  formation 
under  disturbing  influences  of  the  woody  elements  of  plants.  The  cells 
of  the  medullary  parenchyma  in  thorns  {CratcBgus)  remain  unhgnified, 
when  infected  with  a  rust  fungus,  Roestelia.  Finally,  the  formation  of 
cross  walls  may  remain  incomplete,  thus  giving  rise  to  chambers, 
sometimes  communicating  with  each  other. 

Hypoplasia,  as  it  affects  the  cell  contents,  may  be  seen  in  the 
reduction  in  the  number  of  chloroplasts  in  variegated  leaves,  in  plants 
with  pale-green  leaves  and  in  plants  which  grow  in  places  saturated  with 


360  GENERAL   PLANT   PATHOLOGY 

vapor.  The  individual  chlorophyll  grains  may  not  attain  their  normal 
size,  remaining  small.  The  formation  of  chlorophyll  presupposes  a  cer- 
tain temperature,  the  action  of  light,  the  presence  of  iron  and  certain 
organic  food  materials.  Low  temperature  may  reduce  chlorophyll  for- 
mation, as  is  seen  in  grain  seedlings  and  bulbous  outgrowths  or  with 
yellowish  color  grown  under  a  low  temperature.  Deficiency  of  light  and 
iron  causes  etiolation,  more  especially  chlorosis,  or  icterus  in  the  absence 
of  normal  pigment  due  to  the  lack  of  iron,  while  in  vines  unable  to 
absorb  iron  chlorosis  may  take  place  with  abundance  of  iron  in  the  soil. 
Sometimes  it  happens,  on  the  other  hand,  following  the  attacks  of  an 
insect  that  ripening  lemons  remain  green-flecked.  This  condition 
is  due  to  arrested  development  of  the  chloroplasts,  which  normally 
would  be  transformed  to  yellow  chromatophores. 

Light  also  seems  to  influence  the  development  of  the  red  pigment, 
anthocyanin,  as  is  especially  noticeable  in  varieties  of  Coleus,  while 
other  parts,  such  as  rhizomes,  bulbs  and  roots,  which  remain  under- 
ground, are  richly  provided  with  anthocyanin.  Chromogenic  bacteria 
may  lose  the  power  of  producing  pigment,  as  is  illustrated  by  Micro- 
coccus prodigiosus  grown  at  the  high  temperature  of  4o°C.  A.F.W. 
Schimper  and  other  botanists  have  shown  that  the  formation  and  dis- 
tribution of  crystals  of  calcium 'oxalate  in  plants  is  to  a  large  extent 
dependent  on  external  factors.  Shade  leaves  contain  fewer  crystals 
than  sun  leaves  and  plants  grown  in  moist  air,  or  without  light,  are  also 
poor  in  these  crystals. 

C.  Tissue  Differentiation. — The  arrestment  of  tissue  differentiation 
can  be  illustrated  in  simple  algae  where  the  cells  are  united  into  colo- 
nies. When  the  green  alga,  Scenedesmus  caudatus,  the  end  cells  of 
which  have  gelatinous  horns,  is  subjected  to  abnormal  life  conditions 
the  horns  do  not  form.  In  the  consideration  of  tissues  of  multicel- 
lular growths  it  may  be  said  that  there  is  no  organ  in  which  homo- 
plasia  may  not  appear.  Examples  have  been  found  in  the  hepatic  and 
true  mosses. 

The  best  illustrations  of  the  developmental  arrest  of  tissues  are 
found  among  the  flowering  plants,  where  as  one  case  the  guard  cells  of 
the  stomata  may  be  arrested  by  a  lowered  transpiration  and  weak  illumi- 
nation. Stapf  in  his  experiments  with  the  potato,  Solanum  tuberosum, 
showed  that  under  normal  conditions  there  was  one  stoma  for  every 
forty-six  epidermal  cells,  and  in  specimens  matured  by  him  in  gaslight, 


PATHOLOGIC   PLANT   ANATOMY 


36] 


there  was  a  pair  of  guard  cells  for  every  204  epidermal  cells.  The  for- 
mation of  the  hairs  on  the  edge  of  the  ocrea  of  Folygonum  amphibium 
is  entirely  suppressed  in  the  form  natans,  which  is  grown  under  water, 
while  they  are  present  in  the  form  terrestre.  The  modification  of  the 
mesophyll  tissue  in  homoplasia  is  .due  to  the  character  of  the  environ- 
ment. Plants  cultivated  in  places  saturated  with  moisture,  or  after 
infection  by  fungi  or  animals,  show  a  homogeneous  development  of 
the  mesophyll. 

In   homoplasia,    the   vascular   bundles    decrease    in    number,    the 
mechanic  tissue  degenerates  and  the  collenchyma  sometimes  does  not 


A  B 

Fig.  142. — .4,  Cross-section  of  a  normal  thalloid  shoot  of  Lunularia.  {After 
Nestler,  Die  natiirlichen  Pflanzenfamilien  1.  3,  p.  17.)  B,  Cross-section  of  a  thalloid 
shoot  grown  in  the  absence  of  light.  {After  Beauverie  in  Ktister  Pathologische  PJlanzen 
Anatomie,  1903:  42.) 

form.  Thouvenin  by  the  use  of  mechanic  pressure  retarded  the 
development  of  the  woody  tissues  in  the  stem  of  Zinnia.  The  stems  of 
Cardamine  grown  under  water  develop  no  mechanic  tissue.  The 
length  of  the  vascular  bundles  is  less  in  plants  grown  in  moist  places 
over  plants  which  transpire  strongly.  Stahl  found  in  his  study  of  the 
leaves  of  Lactuca  scariola,  that  the  mesophyll  consists  of  palisade  cells 
throughout  in  the  vertical  leaves  and  in  horizontal  leaves  lighted  from 
above  of  palisade  cells  only  on  the  upper  side  of  the  leaf.  If  we  call 
upon  homoplasia  to  explain  the  formation  of  shade  leaves  (Fig.  142),  as 


362  GENERAL   PLANT    PATHOLOGY 

the  unavoidable  product  of  some  arresting  factor,  then  the  structure  of 
shade  leaves  and  those  from  alpine  habitats,  as  well,  as  those  placed  under 
water  and  which  have  a  shade  leaf  structure,  lose  their  remarkable  char- 
acter. Taking  into  consideration  all  of  the  experiments  which  have  been 
performed,  it  may  be  stated  in  concluding  this  chapter,  that  all  of  the 
described  hypoplasias  may '  be  traced  back  to  scanty  nourishment. 
We  are  probably  correct  in  assuming  that  there  is  poor  nutrition  in 
plants  grown  in  distilled  water,  in  the  dark,  in  an  atmosphere  deprived 
of  its  carbon  dioxide  in  moist  places,  or  under  water.  Insufficient 
nourishment  leads  to  an  arrestment  of  differentiation  and  this  becomes 
evident  in  a  number  of  ways. 

Metaplasia 

Metaplasia  has  been  defined  as  the  progressive  change  of  any  cell, 
which  is  not  connected  with  cell  division  and  cell  growth.  The  empha- 
sis in  this  definition  is  upon  the  word  progressive  in  contradistinction  to 
the  word  regressive.  Metaplasia  is  less  important  in  the  histology  of 
plants  than  it  is  in  animal  histology.  Changes  of  a  metaplastic  kind 
are  produced  in  the  cells  of  plants,  especially  in  the  production  of  new 
cell  contents,  or  of  the  cell  wall  by  increase  in  thickness. 

Cell  Contents. — Frequently,  it  happens  with  tubers,  bulbs,  rhizomes 
and  roots  of  many  plants  that  they  develop  a  green  color  in  place  of 
their  normal  chlorophylless  character.  Potato  tubers  kept  in  a  damp, 
warm,  sunny  place  sometimes  develop  a  green  color  and  become 
poisonous  through  the  formation  of  metaplastic  solanin.  Bonnier 
found  that  the  tissues  of  his  experimental  plants  exposed  to  strong  arc 
lights  turned  green  even  to  the  pith.  Likewise  red  pigment  dissolved 
in  cell  sap  may  appear  as  a  metaplastic  change.  For  example,  the  nor- 
mally green  pitchers  of  Sarracenia  purpurea  become  purplish  green  when 
the  plant  is  grown  in  intense  sunlight.  Such  is  also  true  in  the  heather, 
Calluna  vulgaris,  Azolla,  many  succulents  as  Opuntia  and  Sedum.  In- 
jury to  plant  parts  may  be  followed  by  the  development  of  a  red  color. 
The  normal  color  of  the  leaves  of  Saxifraga  Ugulata  are  green,  but  if  leaves 
are  cut  through  the  midrib,  a  red  coloration  developed  along  the  edges 
of  the  wound.  Parasitic  fungi  may  cause  a  local  reddening  of  the  cells 
affected  as  in  certain  fruit  and  leaves  spot  diseases.  The  metaplastic 
formation  of  coloring  matters  appears  in  the  so-called  graft  hybrids. 


PATHOLOGIC    PLANT   ANATOMY  363 

The  excessive  formation  of  starch  in  the  leaves  of  such  plants  as  the 
buckwheat,  Polygonum  fagopyrum,  when  insufficiently  supplied  with 
chlorine  is  a  case  in  point,  as  also  the  unfavorable  nutrition  occasioned 
by  potassium  salts,  while  Schimper  succeeded  in  getting  the  same  ac- 
cumulation of  starch  in  unusual  amounts  in  the  leaves  of  Tradescantia 
selloi  by  cultivation  in  nutrient  solutions  free  from  calcium. 

Cell  Membranes. — The  metaplastic  modifications  of  cell  walls  may 
be  considered  under  two  heads.  The  first  condition  is  found  where 
bordered  pits  are  formed,  as  in  such  orchids  as  Cymbidium  ensifolium, 
LcBlia  anceps  and  Epidendrum  ciliare,  whose  leaves  have  been  scarred. 
The  second  modification  is  seen  where  the  cell  walls  have  been  thick- 
ened abnormally  by  cellulose  knobs,  or  thickenings.  Such  cellulose 
deposits  occur  about  calcium  oxalate  crystals,  oil  drops,  as  in  Piper- 
ace^,  Laurace^  and  about  the  hyphae  of  fungi  which  penetrate  cells, 
the  hyphae  along  with  certain  cytoplasmic  inclusions  being  surrounded 
by  the  cellulose  sheath  bridging  the  space  of  the  cell.  Wortmann  has 
found  heavy  wall  thickenings  in  the  epidermis  and  bark  of  beans  and 
other  twining  plants,  if  they  are  prevented  from  carrying  out  their 
reaction  curvatures,  while  Kiister  noticed  the  lignification  of  the  cell 
walls  in  the  leaves  of  Juglans  under  the  influence  of  certain  plant  lice. 


CHAPTER  XXX 

PATHOLOGIC  PLANT  ANATOMY  (CONTINUED) 

HYPERTROPHY 

The  plant  pathologist  applies  the  word  hypertrophy  to  an  abnormal 
process  of  growth  in  which  the  individual  cells  are  larger  than  the  nor- 
mal, or  when  whole  tissues  become  enlarged,  or  distended.  Cell 
division  is  left  out  of  account  as  a  means  of  the  formation  of  hyper- 
trophied  cells,  or  tissues.  The  cells  which  are  enlarged  may  be  derived 
from  the  meristematic  elements,  which  have  continued  their  growth  to 
the  enlarged  size,  or  cells  continue  their  growth  longer  and  more  in- 
tensively, or  cells  of  permanent  tissue  are  concerned,  which  take  up 
anew  the  process  of  growth  in  size.  The  cell  may  enlarge  in  all  of  its 
dimensions,  so  that  the  original  shape  of  the  cell  is  maintained,  or  it  may 
enlarge  in  one  or  two  directions,  when  the  original  shape  is  no  longer 
kept.  If  the  enlargement  is  in  two  directions  the  cell  will  be  distorted,  if 
in  one  direction  it  will  grow  abnormally  long.  The  extent  of  the  en- 
largement and  its  direction  will  be  determined  by  the  character  of  the 
surrounding  cells,  or  their  absence.  An  hypertrophied  cell  may  be 
surrounded  by  cells  incapable  of  distention,  hence  its  enlargement  will 
be  limited  to  the  size  of  the  available  free  space.  Kiister  distinguished 
two  kinds  of  hypertrophy,  cataplastic  and  prosoplastic.  Cataplastic 
hypertrophy  is  an  abnormal  increase  in  the  volume  of  cells  associated 
with  degenerative  atrophy  of  their  living  contents,  for  the  functional 
decline  of  the  cell  has  been  termed  by  Beneke,  cataplasia.  Prosoplastic 
hypertrophy  involves  new  anatomic  characteristics  and  functional 
activities,  for  the  cells  store  up  fats,  proteins  and  starches,  or  develop 
chlorophyll,  or  red  coloring  matter.  The  involution  forms  of  Bacillus 
radicicola,  which  forms  the  leguminous  root  tubercles,  and  those  of 
the  crown-gall  organism,  Pseudomonas  turn efac tens,  are  examples  of 
simple  hypertrophied  cells  (Fig.  143).  With  these  preliminary  remarks 
it  is  important  to  illustrate  the  different  kinds  of  hypertrophy  which 
have  been  described  by  plant  pathologists.  The  most  simple  cases  are 
those  in  which  the  meristematic  cells  capable  of  division  have  grown  to 

364 


PATHOLOGIC   PLANT   ANATOMY 


365 


an  abnormal  size  by  the  omission  of  cell  division.  Under  the  influence 
of  a  fungous  parasite,  Chytridium  sphac  ell  arum,  the  apical  cells  of  the 
lateral  branches  of  an  alga,  Cladostephus  spongiosus,  stop  dividing  and 
enlarge  into  club-shaped  swellings  at  their  upper  end.  If  specimens  of 
Padina  pavonia,  a  siphonaceous  alga,  be  inverted  and  are  exposed  to 


•    /     /     V      *' 

V             B 

^          >                    C 

»•          'A          *^    D 

Fig.  143. — Drawings  of  rods  and  involution  forms  of  Pseiidotnonas  lumefaciens 
from  young  tumors.  A,  B,  Daisy  on  daisy;  C,  D,  hop  on  red  table  beet;  E,  F,  hop 
on  sugar  beet.  (After  Smith,  Brown,  McCulloch,  Bull.  255,  U.  S.  Bureau  of  Plant 
Industry,  1912.) 

light,  their  spiral  edges  uncoil  and  the  cells  of  the  apex  enlarge  into 
vesicular  form.  The  hyphae  of  the  sterile  mycelium  of  Rozites 
gongylophora  found  in  the  fungous  gardens  of  the  tugging-ant,  Atta, 
show  regular  ball-like  swellings  on  the  ends  of  the  hyphae.  These 
united  into  thick  groups  form  the  kohl-rabi  growths  which  serve  the 
ants  as  food. 


366  GENERAL   PLANT   PATHOLOGY 

Etiolated  plants  afford  interesting  examples  of  hypertrophy,  for 
in  the  absence  of  light  the  internodes  of  the  stems  and  the  petioles 
of  the  leaves  become  inordinately  long.  If  this  follows  cell  divisions, 
then  it  is  a  hyperplastic  phenomena,  but  where  it  is  due  to  the  abnormal 
lengthening  of  existing  cells,  it  is  a  simple  case  of  hypertrophy.  Kiister 
found  in  the  etiolated  peduncles  of  Tulipa  Gesneriana,  that  the  cells 
were  from  a  third  to  a  half  longer  than  the  normal  ones.  Longer  cells 
than  usual  are  produced  in  plants  grown  experimentally  in  moist  air. 

Hyperhydric  tissues  are  abnormal  and  are  formed  by  an  excess  of 
water  within  the  plant.  They  constitute  a  homogeneous  group  from 
a  causative  (etiologic)  point  of  view.  As  examples  may  be  cited 
the  spongy  white  masses  of  cells  which  appear  in  the  lenticels  of  the 
twigs  of  alder,  poplar,  willow  when  such  twigs  are  placed  in  water. 
The  individual  cells  of  this  porous  tissue  are  chlorophylless,  have  a  thin 
layer  of  cytoplasm  and  a  clear  abundant  cell  sap.  Such  water  lenticels 
were  compared  by  Schenck  with  typic  aerenchyma  found  on  numerous 
water  plants.  Such  lenticel  excrescences  arise  from  normal  lenticels 
by  the  enlargement  of  the  phelloderm  cells  and  in  some  cases  the  bark 
cells  lying  under  the  lenticel  hypertrophy.  Von  Tubeuf  and  Devaux 
give  extensive  lists  of  the  plants  which  produce  hypertrophied  lenticels.^ 

Bark  excrescences  form  another  kind  of  hypertrophied  tissue. 
They  have  been  produced  experimentally  on  the  bark  of  the  red  currant, 
Rihes  aureum  (Fig.  144).  In  such  boss-like  excrescences  the  paren- 
chyma cells  of  the  bark  grow  out  into  long  sac-like  cells  of  different 
form  and  size  by  growth  in  a  radial  direction.  Not  only  the  cells  of 
the  outermost  bark  layers  take  part,  but  all  the  elements  down  to  the 
wood  take  part  in  the  abnormal  growth  and  have  become  completely 
or  nearly  colorless.  The  firm  connection  between  bark  cells  is  lost  and 
they  are  separated  from  each  other  by  large  intercellular  spaces. 
Sorauer  kept  cuttings  of  shoots  of  Ribes  aureum  several  years  old  in  a 
vessel  of  water  and  in  moist  air.  At  the  end  of  four  weeks  extensive 
excrescences  were  formed. 

Intumescences  are  small  pustules,  which  are  formed  only  in  limited 
areas,  and  their  formation  follows  the  same  processes  of  growth  as  in 
the  case  of  bark  excrescences.  They  are  known  in  the  branches  of 
Acacia  pendula,  Eucalyptus  rostratus,  Lavatera  trimestris  and  Malope 

^  KtJSTER,  Dr.  Ernst:  Pathological  Plant  Anatomy,  authorized  translation  by 
Frances  Dorrance,  1913:  74-75. 


PATHOLOGIC   PLANT   ANATOMY 


367 


grandiflora.  They  are  formed  on  the  side  of  the  branches  exposed  to 
the  sun  and  the  bark  cells  are  elongated  in  a  radial  direction,  finally 
breaking  through  the  epidermis  as  spongy  masses  of  cells.  Leaves 
also  produce  intumescences.     Originating  in  the  mesophyll  cells,  they 


Fig.  144. — Cross-section  of  a  part  of  a  strongly  hypertrophied  bark  of  Ribes 
aureuni.  K,  Cork;  P,  periderm;  H,  abnormally  elongated  bark  cells.  {Kiisler, 
Pathologische  Pflanzenanatomie,  1903:  80.) 

appear  as  greenish  or  whitish  pustules  of  varying  size  and  beneath  the 
cells  lose  their  chlorophyll  content.  Cataplastic  hypertrophy  explains 
the  origin  of  some  intumescences.  For  example,  the  lower  cells  of  the 
several-layered  epidermis  of  Ficus  elastica  are  pressed  together  by  the 


368  GENERAL   PLANT   PATHOLOGY 

growth  of  the  mesophyll  cells  and  the  space  originally  occupied  by  the 
former  is  finally  filled  with  the  cells  of  the  mesophyll.  Excess  of  water 
is  one  of  the  contributing  causes  in  the  formation  of  intumescences, 
as  also  treatment  of  plants  with  poisons,  especially  copper  salts. 

Abnormal  succulence,  as  an  hypertrophy,  is  such  where  plants  with 
normally  thin  leaves,  develop  thick  ones  in  their  place.  Salt  solutions, 
if  used  experimentally  upon  certain  plants,  may  induce  succulency. 
LeSage  produced  artificial  succulence  in  the  leaves  of  Lepidium  sativum 
by  abundant  doses  of  common  salt,  NaCl.  The  mesophyll  cells  were 
elongated  greatly. 


Fig.  145. — Cross-section  through  the  wounded  border  of  a  cabbage  leaf.  The 
hypertrophied  mesophyll  cells  are  enlarged  into  vesicular  swellings.  {Kilster,  Palh- 
ologische  PJlanzenanatomie,  1903:  94.) 

Callous  hypertrophy  arises  after  an  injury  when  the  living  cells  of  an 
organ  enlarge  without  division,  especially  at  the  edge  of  the  wound, 
where  they  may  enlarge  to  many  times  their  normal  volume  (Fig.  145). 
As  it  frequently  happens  that  cell  divisions  follow  an  injury,  it  is  not 
always  easy  to  distinguish  between  callous  hypertrophies  and  callous 
hyperplasias.  We  find  callus  hypertrophies  among  the  thallophytes, 
as  in  Padina  pavonia,  and  in  the  higher  plants  where  the  bark,  wood 
parenchyma,  leaves  are  affected.  Kiister  produced  callous  hyper- 
trophies near  the  upper  surface  of  the  cut  by  keeping  one  end  of  the 


PATHOLOGIC   PLANT    ANATOMY 


369 


cutting  under  water,  the  other  extending  into  moist  air.  The  bark 
cells  were  enlarged  greatly,  producing  ball-Hke  or  weakly  lobed  forms. 
Only  single  cells  in  the  bud  hypertrophied  and  they  grew  out  into  large 
colorless  vesicles.  Miehe  has  found  Tradescantia  virginica  a  suitable 
object  to  produce  callous  hypertrophies  experimentally.  The  destruc- 
tion of  cells,  or  cell  groups,  of  the  epidermis  causes  the  formation  of 
empty  places  which  are  filled  by  the  neighboring  cells  which  close  the 


Fig.  146. — Pitted  vessel  of  black  locust, 
Robinia  pseudacacia,  filled  with  enlarged 
parenchyma  cells  or  tyloses.  At  a  the  con- 
nection between  tyloses  and  original  cell  is 
seen.  (Kiister,  Pathologische  Pflanzenanal- 
omie,  1903:  100. 


Fig.  147. — Cross-section  through 
old  wood  of  Mespilodaphne  sassafras. 
The  lower  vessels  contain  .stone 
tyloses,  the  upper  besides  stone 
tyloses,  contain  thin-walled  tyloses. 
{After  Molisch  in  Kiister,  Pathologische 
Pflanzenanatomie,  1903:  100.) 


opening.  Haberlandt  in  his  culture  of  isolated  tissue  elements  obtained 
abnormally  large  cells  which  should  be  classed  among  callous  hyper- 
trophies. He  kept  alive  isolated  mesophyll  cells  from  the  leaves  of  the 
purple  dead  nettle,  Lamiuni  purpureiim,  for  weeks  in  Knop's  solution, 
or  in  nutrient  sugars,  and  these  cells  grew  perceptibly  at  the  same  time 
that  a  thickening  of  their  membranes  took  place.  The  exact  causative 
influence  in  the  development  of  callous  hypertrophies  is  still  an  open 
question. 
24 


370  GENERAL   PLANT   PATHOLOGY 

Tyloses^  are  more  or  less  closely  packed,  bladder-shaped  intrusions 
derived  from  the  parenchyma  cells  adjoining  the  cavities  of  water- 
conducting  elements  into  which  they  project,  often  completely  blocking 
the  cavities  (Fig.  146).  They  were  first  investigated  by  Hermine  von 
Reichenbach,  who  noticed  that  the  swelling  is  not  cut  ofiF  from  the 
parent  cell  by  a  septum.  They  arise  frequently  in  association  with  one- 
sided bordered  pits,  the  limiting  membranes  of  which  undergo  active 
surface  growth  and  thus  push  their  way  into  the  cavities  of  the  vessels 
(Fig.  147).  Several  tyloses  may  arise  from  a  single  epidermal  cell.  They 
occur  beneath  branch  scars  that  have  been  formed  by  a  branch  breaking 
off  and  also  at  the  wounded  end  of  cuttings  being  formed  in  such 
numbers,  that  they  become  flattened  by  mutual  pressure.  The  cavities 
of  vessels  are  thus  filled  and  they  probably  serve,  as  Boehm  first  sug- 
gested, to  plug  up  the  cavities  of  the  water-conducting  tubes  that  have 
suffered  mechanic  injury.  This  explanation  suffices  for  such  special 
cases  of  injury,  but  tyloses  are  formed  in  uninjured  vessels  where  they 
obviously  do  not  serve  to  close  up  a  wound.  Haberlandt  believes  that 
tyloses  of  this  last-mentioned  type  take  some  part  in  the  process  of 
conduction,  by  increasing  the  surface  of  contact  between  the  vessels 
and  the  neighboring  parenchyma  cells.  Kiister  in  his  "Pathological 
Plant  Anatomy"  gives  a  detailed  account  of  the  different  kinds  of 
tyloses  and  their  method  of  formation,  which  need  hardly  be  discussed 
in  a  text-book  for  student  use.  Molisch  gives  a  list  of  plants  in  which 
tyloses  have  been  found.  Sometimes  tyloses  fill  the  air  chambers  of 
the  stomata  partially  or  almost  entirely,  where  the  epidermal  cells 
adjacent  to  the  guard  cells  grow  out  into  large  unicellular  bags,  as  in 
Tradescantia  viridis. 

Gall  hypertrophies  are  those  which  are  produced  by  the  effect  of  a 
poison  formed  by  an  attacking  animal,  or  plant.  The  tissue  products 
are  the  most  diverse  and  a  sharp  distinction  cannot  be  drawn  between 
hypertrophic  and  hyperplastic  gall  tissues.  Gall  hypertrophies  usually 
occur  in  the  epidermal  and  the  fundamental  tissues  of  various  plants. 
The  galls  of  the  fungi  belonging  to  the  family  Chytridiace^,  namely, 
those  occasioned  by  species  of  Synchytrium,  are  very  simple,  for  the 
entire  life  history  of  the  fungous  parasite  is  passed  in  a  single  cell  of  the 

1  Gerry,  Eloise:  Tyloses:  Their  Occurrence  and  Practical  Significance  in  Some 
American  Woods.  Journal  of  Agricultural  Research,  i:  445-470,  with  8  plates, 
March  25,  1914. 


PATHOLOGIC   PLANT   ANATOMY  37 1 

host.  The  zoospores  of  the  species  of  Synchytrium  penetrate  the  epi- 
dermal cells  and  incite  these  cells  to  active  growth  causing  their  enlarge- 
ment, as  in  the  cells  attacked  by  Synchytrium  drabcB.  Sometimes  the 
infected  cell  grows  inordinately  and  pushes  the  mesophyll  cells  lying 
below  apart,  until  it  projects  into  the  underlying  cells  as  a  spheric 
pouch.  If  the  neighboring  epidermal  cells  are  stimulated  warts  are 
formed. 

The  second  group  of  gall  hypertrophies  are  certain  hair-like  develop- 
ments of  epidermal  cells  due  to  the  irritation  of  certain  mites  of  the 
genus  Phytoptus,  which  produce  felt-galls,  or  Erineum.  These  erineum 
structures  arise  in  clusters  on  the  surface  of  leaves  of  such  trees  as 
maples,  alders,  birches,  beeches,  oaks,  willows,  limes  and  on  herba- 
ceous plants  belonging  to  the  genera  Geranium,  Mentha,  Salvia,  etc. 
These  outgrowths  so  resemble  fungi,  that  Persoon  was  deceived  into 
so  believing.  They  are  usually  pale,  or  even  white  at  first,  and  they 
turn  brown  aS  the  hair-like  outgrowths  die  and  lose  their  sap,  but 
since  the  latter  may  be  colored  yellow,  red  or  purple,  the  outgrowths  are 
conspicuous  objects  on  smooth  leaves.  The  botanist  Malpighi  in 
1675-1679  was  the  first  to  call  attention  to  these  galls.  One-celled 
erinea  are  the  rule,  but  multicellular  abnormal  hairs  are  formed  by  the 
hypertrophies  of  the  normal  trichomes  as  Frank  reports  on  Quercus 
(Bgilops. 

Gall  hypertrophies,  where  the  ground  tissues  of  plants  participate  in 
their  formation,  are  known.  The  roots  of  the  Cycadace^  develop 
sacs  out  of  their  parenchyma  cells,  so  that  large  intercellular  spaces  are 
formed  in  which  a  blue-green  alga,  Anabcena  cycadearum,  the  causal 
organism,  lives.  Galls  produced  by  flies  and  belonging  to  the  group  of 
zoocecidia  may  be  taken  as  illustrations  of  gall  hypertrophies.  One  is 
known  as  the  window  gall  of  the  maple,  and  the  other  is  a  reddish-brown, 
bladder  gall  occurring  on  the  leaves  of  Viburnum  lantanum. 

Multinuclear  giant  cells  may  be  formed  in  plants,  if  the  nuclei  divide 
regularly,  but  for  some  reason  the  formation  of  cross-walls  becomes 
impossible.  The  cells  are  stimulated  to  abnormal  growth  forming  the 
so-called  giant  cells.  Such  hypertrophies  are  associated  with  an  in- 
crease of  the  cytoplasmic  contents  of  the  cells.  Such  giant  cells  are 
those  produced  by  certain  Nematode  worms  of  the  genus  Heterodera  on 
such  host  plants  as  Beta,  Coleus,  Daucus,  Plant  ago  and  Saccharum  (Fig. 
148).     Prilleux  produced  multinuclear  giant  cells  in  seedlings  which 


372 


GENERAL   PLANT    PATHOLOGY 


were  cultivated  at  an  abnormally  high  temperature.     The  number  of 
nuclei  rarely  exceeded  three. 

Multinucleate  cells  occur  in  crown  gall  which  are  perhaps  compar- 
able to  the  giant  tells  of  the  animal  histologist.  Cancer  specialists  have 
divided  these  into  two  groups,  viz.,  foreign-body  giant  cells  in  which  the 


Fig.  148.- — Cross-section  of  a  part  of  a  root  gall  of  Circaa  luteliana  in  old  stage, 
numerous  giant  cells  are  seen,  the  nuclei  of  which  have  begun  to  degenerate;  b,  irreg- 
ularly branched  nuclei  out  of  the  giant  cells  dividing  by  amitosia  within  anuceoli; 
C,  a  single  multinucleate  giant  cell.  {After  Tischler  in  Kuster,  Pathologische  Pflanzen- 
anatomie,  1903:  128.) 


stimulus  is  some  introduced  foreign  substance,  and  genuine  ones  in 
which  no  foreign  bodies  are  visible.  There  is  probably  no  real  distinc- 
tion other  than  that  those  occupied  by  parasites  are  malignant  and  those 
induced  by  non-Hving  granules  are  harmless.  The  cells  in  question  in 
crown  gall  are  not  very  large,  but   they  contain  several  nuclei   (Fig. 


PATHOLOGIC   PLANT   ANATOMY 


373 


149).  Four  nuclei  in  one  cell  is  the  most  we  have  seen,  but  it  is  prob- 
able that  larger  numbers  occur.  It  would  seem  from  the  studies  of 
Erwin  F.  Smith,  which,  however,  are  incomplete,  that  most  of  the  cell 
divisions  in  crown  gall  are  by  mitosis.  Frequently,  however,  there 
have  been  found  nuclei  variously  lobed  and  in  process  of  amitotic 
division,  and  this  is  probably  the  way  in  which  several  nuclei  are 
formed  in  one  cell  (Fig.  149). 


Fig.  149. — Nuclear  division  in  crown  gall;  1-16,  cells  showing  amitotic  (direct) 
division;  17,  mitotic  division  in  which  more  chromosomes  have  passed  to  one  pole 
than  to  the  other.  (After  Smith,  Brown,  McCulloch,  Bull.  255,  U.  S.  Bureau  of  Planl 
Industry,  1912.) 

HYPERPLASIA 


Virchow  in  his  "  Cellularpathologie "  (1858:  58)  defined  hyper- 
plasia as  all  abnormal  quantitative  increase,  produced  by  cell  division, 
and  that  definition  will  be  adopted  here.  It  is  very  difficult  in  practice 
to  distinguish  without  a  careful  study  between  hypertrophy  and  hyper- 
plasia, but  in  the  latter  abnormalities  are  produced  by  cell  division, 


374  GENERAL    PLANT   PATHOLOGY 

while  in  hy})crtiophy  they  are  not.  A  number  of  well-defined  groups  of 
vegetative  hyperplasias  may  be  distinguished  by  their  etiology.  Chemic 
stimulation  may  be  the  cause  of  some,  injury  the  cause  of  others.  The 
normal  currents  of  foodstuffs  may  be  clogged,  the  food  may  be  irregu- 
larly distributed  and  these  interferences  with  normal  processes  may 
result  in  proliferations  and  other  abnormalities.  Special  stimuli  may 
also  bring  about  abnormal  supplies  of  food  with  consequent  hyperplas- 
tic tissue  formation.  The  study  of  the  abnormality  to  determine  its 
kind  must  be  based  on  histologic  analysis.  If  in  our  histologic  examina- 
tion, we  discover  that  the  abnormal  tissues  resemble  the  corresponding 
normal  plant  parts,  we  are  dealing  with  homooplasia;  if  they  differ  from 
the  normal,  that  is  are  composed  of  cells  different  from  the  correspond- 
ing normal  ones,  then  we  have  a  case  of  heteroplasia. 

Heteroplastic  excrescences  are  of  great  interest  histologically.  The 
difference  between  normal  and  abnormal  states  is  sometimes  greatly 
diverse.  This  difference  may  be  one  of  size,  of  tissue  differentiation,  of 
constitution,  and  it  is  important  in  our  pathologic  study  to  determine 
the  nature  of  the  differences  between  normal  and  abnormal  conditions. 
Thus,  when  we  find  a  less  differentiated  tissue  produced  by  abnormal 
cell  division  without  regard  to  the  increase  in  the  numbers  of  cells,  we  can 
speak  of  the  degeneration  of  tissue  formation  combined  with  an  increase 
of  volume.  This  is  known  as  cataplasy,  and  the  products  of  the  cata- 
plastic  processes  as  cataplasms  and  the  kind  of  hyperplasia  illustrated 
in  these  abnormal  changes  as  cataplastic  hyperplasia.  When,  on  the 
other  hand,  we  find  new  histologic  characteristics  and  functional  activi- 
ties associated  with  hyperplasia,  we  speak  of  prosoplasy,  of  prosoplasms, 
and  of  prosoplastic  hyperplasia. 

Homooplasia. — This  term  may  be  defined  as  abnormal  tissue  forma- 
tion produced  by  an  increase  of  the  normal  elements;  it  has  a  limited 
use  to  abnormalities,  not  to  increase  in  size  of  normal  organs  by  a  mere 
increase  in  the  number  of  cells.  We  would  not  use  the  word  homo- 
oplasia for  the  unusually  large  leaves  which  of  normal  form  and  texture 
appear  on  the  shoots  which  arise  from  tree  stumps  and  which  have  been 
studied  by  the  writer  in  a  number  of  our  American  forest  trees,  such  as 
the  tulip  tree,  Liriodendron  tulipijera.  Homooplasia  is  opposed  to  the 
phenomena  of  giant  growth  here  mentioned. 

Localized  tissue  excrescences  composed  of  the  same  histologic  ele- 
ments and  of  homooplastic  character  are  not  common.     Occasionally 


PATHOLOGIC    PLANT    ANATOMY  375 

sugar  beets  continue  their  growth  to  abnormal  thickness  by  the  forma- 
tion of  ridge-like  tissue  excrescences  composed  of  normal  layers  of  tis- 
sues which  extend  longitudinally.  De  Vries  investigated  a  case  where 
new  cariibial  rings  were  formed  outside  of  the  latest  ones  of  the  first  year 
coincident  with  an  arrestment  of  activity.  Hottas  incased  roots  of 
Viciafaba  in  plaster  casts  pierced  by  holes.  He  found  that  by  correla- 
tive growth  homooplastic  excrescences  filled  the  holes. 

Some  kinds  of  homooplasias  are  characterized  by  the  fact,  that  only 
single  tissue  forms  of  an  organ  are  developed  unusually  without  the  for- 
mation of  local  excrescences  by  which  means  the  histology  of  the  organ 
is  altered.  Increased  demand  upon  a  tissue  may  result  in  the  formation 
of  abnormally  abundant  tissue  and  to  this  the  name  of  activity  homo- 
oplasias has  been  given.  Various  experiments  have  been  conducted  in 
the  attempt  to  form  mechanic  tissue  by  putting  an  increased  mechanic 
demand  upon  plant  tissues.  The  experiments  of  Kiister  with  sunflower 
stems  were  negative,  as  also  those  of  Wiedersheim  with  branches  of 
beech  and  ash,  for  he  found  no  strengthening  of  the  hard  bast  in  his 
experiments.  He  proved,  however,  an  increase  of  stereids  in  the 
strained  branches  of  Corylns  avellana.  Vochting  has  shown  that  hori- 
zontal stalks  of  the  Savoy  cabbage  strained  at  the  extremity  by  hanging 
weights  developed  thickenings  on  the  upper  side  of  the  branch.  De 
Vries  has  described  an  abnormal  potato  tuber  in  which  through  the  need 
of  conduction  of  plastic  substances  the  bundles  of  the  tuber  had  devel- 
oped to  an  extent  unusual  to  the  normal  plant.  The  wood  and  bast 
portions  were  both  increased.  Vochting's  experiments  with  potato 
tubers  supplement  those  of  de  Vries;  for  he  succeeded  in  interpolating 
the  potato  tuber  as  an  element  in  the  potato  plants  grown  from  it  and 
succeeded  in  getting  hyperplastically  developed  vascular  bundles. 

Correlation  homooplasias  result  when  there  is  a  local  arrestment  of 
growth,  and  growth  is  started  elsewhere  with  homooplastic  changes  in 
the  tissues.  The  experiments  of  Boirivant  and  Braun  have  proved  this 
in  a  number  of  plants.  Only  one  case  of  callus  homooplasia  has  been 
reported  and  it  is  described  by  Schilberszy,  who  succeeded  in  stimulat- 
ing an  increase  of  vascular  tissue  in  the  stalks  of  Phaseohis  mtdtiflorus 
through  injury.  No  positive  cases  are  known  where  homooplasias 
occur  in  the  formation  of  galls. 

Heteroplasias. — This  term  of  pathologic  anatomy  is  used  when 
there  is  a  quantitative  increase  of  an  organ  in  which  by  abnormal  di- 


376  GENERAL  PLANT   PATHOLOGY 

vision  of  the  cells  there  are  produced  tissues,  the  single  elements  of  which 
have  no  resemblance  to  normal  ones.  Size  of  cells  is  of  relatively  little 
interest  in  the  study  of  these  abnormalities.  More  important  are  cata- 
plasmic  and  prosoplasmic  tissues,  which  are  formed  in  heteroplasia. 
Cataplasmic  tissues  are  those  which  are  more  simply  constructed  than 
the  corresponding  normal  tissues,  while  prosoplasmic  tissues  are  those  in 
which  we  can  see  processes  of  differentiation  in  the  formation  of  their 
single  cells  and  in  the  distribution  of  their  different  elements,  which  are 
not  manifest  in  the  formation  of  the  corresponding  normal  tissue. 

The  material  illustrating  the  various  kinds  of  heteroplasia  may  be 
treated  of  under  the  following  heads: 

1.  Correlation-heteroplasms      1 

2.  Calluses  \  Cataplasms 
Heteroplasias     3.  Wound- wood                         J 

4.  Wound-cork 


Galls 


I .  Correlation-heteroplasms 


(a)  Cataplasms 

(b)  Prosoplasms 


This  term  is  applied  to  cases  where  the  normal  growth  of  any  plant 
is  arrested  at  its  vegetative  points  by  any  causative  factors  whatsoever, 
and  where  under  the  stimulus  of  the  unused  nutritive  materials  some  part 
of  the  plant  develops  abnormal  growth  and  tissues.  Vochting  has 
studied  this  subject  in  all  of  its  details.  He  found  that  decapitation 
of  sunflower  plants  resulted  in  the  production  of  tuber-like  swellings 
on  the  roots  and  that  in  the  aerial  runners  of  Oxalis  crassicaulis  filled 
with  reserve  materials  that  removal  of  the  apical  cells  and  all  axillary 
bud  cells  resulted  in  the  formation  of  swellings  on  the  leaves  and 
internodes.  According  to  Vochting,  the  parenchyma  participates,  also 
the  vascular  bundles,  which  have  fewer  ducts  than  the  normal  ones. 
The  sieve  tubes,  however,  are  richly  developed  and  extensive  funda- 
mental tissue  outgrowths  are  found  between  bast  and  wood.  The  first 
experimentally  produced  correlation-heteroplasms  were  made  by  Sachs. 
He  cut  off  all  the  vegetative  points  of  pumpkin  plants.  He  found,  as  a 
result,  that  the  embryonic  root  cells  present  in  the  stem  at  the  right 
and  left  of  each  petiole  grow  out  into  short-stalked  tubers,  as  large 
as  marbles,  in  which  the  root  cap  and  vegetative  point  are  absent  and 


PATHOLOGIC   PLANT   ANATOMY 


377 


the  axillary  fibrovascular  cord  is  resolved  into  a  circle  of  isolated  bundles 
separated  by  chlorophyll-containing  cells. 

2.  Callus 


Callus  may  be  defined  in  the  widest  sense  of  the  word  as  all  cell  and 
tissue  forms  produced  subsequent  to  and  as  a  result  of  injury.  In 
many  plants  and  plant  organs,  only  a  metaplastic  change  of  the  cells 
was  incited  by  the  injury  (callus-metaplasia);  in  others,  the  cells  laid 
bare  showed  an  abnormal  growth  and  were  changed  into  voluminous 
vesicles  and  sacs  (callus-hypertrophy),  or  an 
increase  of  the  normal  tissue  may  result  from 
wound  stimuli  (callus-homooplasia).  The 
cells  may  be  abundant  after  an  injury  owing 
to  active  cell  division  and  heteroplastic  tissue 
arises  (callus-heteroplasia).  When  excres- 
cences arise,  which  are  composed  of  cells  very 
little  differentiated  and  of  the  simplest  form, 
they  are  called  cataplasms.  If  produced  after 
injury,  they  are  found  to  differ  greatly.  The 
tissues  produced  after  an  injury,  if  resembling 
cork,  are  termed  wound-cork,  if  similar  to  those 
of  wood,  they  are  called  wound-wood  and 
where  we  have  the  healing  tissue  composed  of 
nearly  homogeneous  parenchyma,  it  is  called 
simply  callus. 

Callous  tissue  may  be  formed  as  wound 
tissue  in  very  different  plant  groups.  It  has 
been  found  in  the  algal  fungi  and  vascular 
cryptogams.  The  woody  seed  plants  have  been  studied  carefully  as 
to  the  formation  of  callus,  because  of  its  economic  importance  in  forestry 
and  horticulture.  Rose,  poplar,  or  willow  cuttings  kept  in  moist  air 
and  at  a  proper  temperature  after  a  few  days  form  a  ring-like  tissue 
excrescence  from  the  cambium  of  the  cut  surface.  This  spreads  out 
rapidly  and  finally  closes  over  the  wound.  Such  rolls  of  tissue  have 
been  called  callus  (callus,  hard  skin). 

Callus  at  least  in  its  first  stages  appears  in  the  form  of  a  ring,  some- 
times it  is  irregular  in  its  formation,  often  being  lacking  in  some  places 


Fig.  150. — Longitudinal 
section  of  a  callused  end  of 
a  cutting.  C,  C,  Callus  de- 
veloped from  cambium;  H, 
wood;  R,  bark.  (After 
Kiisler,  p.  159.) 


378 


GENERAL    PLANT    PATHOLOGY 


and  this  is  sometimes  due  to  limitations  of  space  relations.  Sometimes 
the  callus  is  most  luxuriant,  as  in  Cuttings  of  Populus  pyramidalis 
(Figs.  150  and  151)  and  Lamium  orvala  (Fig.  152),  which  produces  the 
largest  callous  rolls  among  herbaceous  plants.     All  organs  of  the  plant 


Fig.  151. — Cross-section  of  a  calloused  end  of  a 
poplar  cutting.  G,  Vessel;  M,  pith  ray.  {After 
Krister,  p.  159-) 


Fig.  153.  —  Stem  of 
Lamium  orvala  with  strong  cal- 
lous growth^  {After  Kuster.) 


are  capable  of  producing  callus,  such  as  roots,  stems  and  leaves,  yet 
all  parts  of  all  plants  do  not  have  the  capacity  of  forming  it.  Such 
growth  seems  to  reside  in  the  living  elements  of  exposed  tissue  and  the 
productive  power  of  different  kinds  of  tissues  varies  greatly.  Cam- 
bium is  the  most  active  layer  in  the  production  of  callus  and  next  to 


PATHOLOGIC    PLANT    ANATOMY  379 

the  cambium  the  primary  and  secondary  bark  tissues.  The  epidermis 
plays  an  unimportant  role.     Pith  also  can  develop  callus. 

The  investigations  of  R.  Hoffman,  Kiister  and  Stoll  go  to  show  that 
the  cambial  cells  when  division  takes  place  after  injury  are  not  re- 
stricted to  the  mode  of  normal  division  but  can  grow  in  every  direction. 
It  is  certain,  therefore,  that  the  conditions  of  changed  pressure  are  of 
importance  and  significance,  and  yet  this  fact  alone  is  hardly  sufl&cient 
to  explain  the  phenomena  of  growth  subsequent  to  an  injury.  The 
cell  divisions  are  very  regular  and  rapid  in  those  woody  plants  which 
form  callus. 

Cuttings  of  woody  plants,  such  as  Populus  pyramidalis  (Fig.  150),  if 
placed  in  water  and  covered  with  a  bell  glass,  so  that  the  upper  end 
extends  above  the  water  into  the  moist  air,  shows  early  division  of  the 
cambial  cells  near  the  upper  wounded  surface.  We  find  these  cells 
are  divided  by  walls  perpendicular  to  their  long  axis,  and  in  a  lively 
manner,  by  forming  tangential  walls,  causing  an  abnormally  intensive 
growth  in  thickness  of  the  cutting  near  the  injured  place.  A  strong 
callus  has  been  formed  by  abundant  division  of  the  cambial  cells  and  the 
cutting  assumes  a  club-shaped  form  at  its  upper  end.  The  wedge, 
which  is  formed  in  this  way  between  the  wood  and  bast,  has  been  termed 
by  Th.  Hartig  the  "Lohdenwedge,"  which  might  be  termed  more  ap- 
propriately in  English  the  healing  wedge.  In  the  formation  of  this 
wedge,  the  cambial  cells  have  divided  just  as  under  normal  conditions, 
but  the  relief  of  pressure  has  caused  some  of  the  outer  cells  to  protrude 
to  form  the  enlarged  part  of  the  wedge  with  the  outer  cells  bent 
strongly.  Primary  bark  as  in  Salix  easily  forms  callus,  and  petioles  and 
leaves  often  form  abundant  callus. 

Histologically  the  tissues  of  callus  are  distinguished  by  the  slight 
differentiation  of  their  cells.  The  cushions  of  callus  in  many  kinds  of 
cuttings  are  made  up  of  the  same  kinds  of  cells  and  in  a  homogeneous 
fashion.  The  cells  are  typically  nascent  ones  with  thin  cell  wall,  pro- 
toplasmic contents  and  a  colorless  cell  sap.  If  the  growth  is  slow,  the 
callous  cells  are  small  and  closely  fitted  together,  but  with  rapid  growth 
the  cells  are  large  and  loosely  placed  with  conspicuous  intercellular 
spaces.  Tracheids  are  absent  from  the  upper  cells  of  the  cushion  of 
callus,  but  in  the  lower  part  of  the  healing  wedge  some  of  the  cells 
assume  the  tracheal  character.  The  formation  of  a  tegumentary  layer 
is  next  to  the  development  of  tracheids  the  most  interesting  process  of 


380  GENERAL   PLANT   PATHOLOGY 

differentation  in  the  callus.  The  callus  of  poplar  cuttings  is  favorable 
for  a  study  of  its  formation.  The  outer  cells  of  the  wedge  of  healing 
are  long  and  pouch-like,  and  their  outer  walls  give  the  cork  reaction, 
since  they  take  up  Sudan  III  with  avidity,  and  at  the  same  time  are 
colored  with  hydrochloric  acid  and  phloroglucin.  Sooner  or  later,  a 
cork  cambium  is  produced  in  the  outer  cell  layers  of  most  callous  for- 
mations. Massart,  who  first  studied  the  nuclear  phenomena  in  callous 
tissue,  rarely  found  that  the  cells  contained  more  than  one  nucleus. 
He  found  that  direct  nuclear  division  took  place  after  wounding  in 
Cucurbita,  Ricinus  and  Tradescantia,  while  Nathansohn  found  mitosis 
in  the  callus  of  the  divided  roots  of  Vicia  faba  and  both  mitosis  and 
amitosis  in  that  of  poplar  cuttings. 

Conditions  of  Callous  Formation 

The  behavior  of  cuttings  from  different  plants  varies  within  rather 
wide  limits.  Some  cuttings  develop  callus  quickly,  others  slowly,  and 
the  quality  of  the  callous  tissues  differs  as  greatly.  The  poplar  develops 
a  large  amount  of  callus,  while  cuttings  of  elm,  willow  and  oak  form 
only  a  low  callus  ring.  Organs  rich  in  foodstuffs  form  callus  more 
quickly  than  those  poor  in  food  materials.  For  example,  the  cotyle- 
dons of  Phaseolus  and  Vicia,  rich  in  proteins  and  starch,  develop  callus 
to  an  extraordinary  degree.  Moisture  is  an  important  factor  in  the 
formation  of  callus,  for  it  is  formed  in  water,  but  better  in  moist  air, 
and  not  at  all  in  dry  air.  Cuttings  of  poplar  with  both  cut  ends  in 
moist  air  develop  callus  at  both  extremities,  but  usually  there  is  a 
polarity  shown.  Cut-off  petioles  of  the  poplar  form  a  more  prolific 
callus  at  the  basal  end  of  the  petiole  than  at  the  end  nearer  the  leaf 
blade  With  stem  cuttings,  the  callus  is  best  developed  at  the  basal 
end  in  preference  to  the  apical.  Pieces  of  dandelion  roots,  3  cm.  long, 
kept  in  a  moist  place,  show  most  abundant  callus  on  the  upper  stem 
ends  and  not  at  all,  or  only  slowly  at  the  apex,  but  in  alfalfa  a  power- 
ful tuber-like  callus  is  produced  at  the  root  end  and  feebly  at  the  sprout 
end.  So  that  having  varied  the  external  conditions  of  their  formation, 
it  becomes  evident  that  internal  conditions  are  active  and  these  prob- 
ably depend  upon  inequalities  in  the  nutritive  condition  of  the  cut 
parts  and  also  on  the  direction  of  established  sap  flow. 

Loosely  connected  with  pathologic  anatomy  ^re  the  regenerative 


PATHOLOGIC   PLANT  ANATOMY  38 1 

processes  ivhich  result  in  the  formation  of  the  vegetative  points  of  roots 
and  shoots  following  an  injury.  Following  an  injury  in  very  many 
woody  plants,  there  is  a  formation  of  adventitious  roots  and  adventi- 
tious shoots  which  grow  from  vegetative  points  developed  directly 
from  the  permanent  tissue  of  the  wounded  plant  organs,  but  this  opera- 
tion is  necessarily  preceded  by  formation  of  callus  and  in  some  cases 
the  new  vegetative  points  are  developed  directly  from  the  callus. 
Upon  these  functional  operations  depend  the  success  of  the  horticultural 
operations  of  the  making  and  establishment  of  cuttings  of  roots,  stems, 
and  leaves.  A  very  large  number  of  plants  may  be  raised  by  means  of 
cuttings.  Soft-wooded,  or  herbaceous  cuttings  having  leaves  are  used 
in  many  cases,  the  shoots  being  in  a  half-ripened  condition,  that  is 
neither  too  young  nor  too  old,  dry  and  woody.  Such  cuttings  are 
usually  inserted  in  sandy  or  gritty  soil,  and  most  of  the  leaves  are 
stripped  off  to  check  transpiration  of  moisture.  Several  leaves  are 
retained,  so  that  a  certain  amount  of  assimilation  can  be  carried  on  to 
induce  callus  formation. 


WOUND- WOOD. 

The  wood,  which  is  formed  on  the  surface  of  the  exposed  wood  of 
the  stem  and  on  the  inner  surface  of  the  detached  bast,  is  distinguished 
from  ordinary  wood  by  its  abnormal  structure,  and  especially  by  the 
shortness  of  its  cells  and  the  absence,  or  scarcity  of  vessels.  Hugo  de 
Vries,^  who  was  the  first  to  direct  attention  to  this  abnormality,  called 
such  wood,  wound-wood.  Such  abnormal  wood  is  distinguished  from 
the  normal  xylem  by  its  simple  histologic  character,  and  is  to  be  added 
to  the  list  of  cataplasms. 

The  difference  between  wound-wood  and  normal  wood  depends 
upon  whether  its  formation  has  been  brought  about  by  cross  cuts  into 
the  cambium,  or  by  longitudinal  wounds.  In  the  latter,  the  wound- 
wood  is  distinguished  by  a  wide-celled  structure  and  by  more  numerous 
ducts  than  in  normal  wood,  but  the  libriform  fibers  are  less  in  evidence. 
Hugo  de  Vries  studied  Caragana  arborescens  and  proved  that  the 
wound  stimulus  caused  the  formation  of  wound  tissue  7  cm.  from  the 
wound  itself.  The  nearer  the  cells  of  the  cambium  are  to  the  wound 
the  more  cross  walls  are  formed,  so  that  the  short-celled  zone  of  the 

1  DE  Vries,  Hugo:  Ueber  Wundholz.  Flora,  1876:  2. 


382  GENERAL   PLANT   PATHOLOGY 

wound-wood  is  produced  near  the  place  of  injury,  the  transitional  forms 
at  a  greater  distance  and  then  the  long-celled  zone,  which  is  formed 
from  undivided  cells  of  the  cambium.  The  daughter  cells  of  the  cam- 
bium of  the  short-celled  zone  form  near  the  edges  of  the  injured  part, 
a  wound-wood  composed  of  polyhedric  fundamental  tissue  cells  re- 
sembling the  medullary  ray  cells  of  normal  wood,  only  a  few  of  such  ele- 
ments develop  into  parenchymatous  tracheids.  The  cells  of  the  long- 
celled  zone  retain  the  character  of  wood  parenchyma,  but  between  them 
narrow  vascular  cells  united  into  strand-like  groups  are  formed,  while 
wood  fibers  and  broad  ducts  are  absent.  Such  formed  elements  have 
been  termed  primary  wound-wood  by  de  Vries,  and  later,  there  occurs 
the  production  of  a  secondary  wound-wood  in  which  the  cells  gradually 
assume  a  normal  form.  Abnormal  resin  ducts  are  formed  in  wound- 
wood  and  these  ducts  are  often  more  numerous  in  abnormal  wood  than 
in  the  normal. 

Sometimes  the  wound-wood  does  not  form  definite  stratified  tissues. 
Occasionally  tracheid-like  cells  are  found  in  the  callus  which  become 
united  into  ball-like  groups  separated  from  the  normal  wood.  Wood 
fibers,  which  have  an  irregular  course,  have  formed  the  gnarled  wood. 

The  pith  may  take  part  in  the  formation  of  wound-wood,  for  it  is 
highly  capable  of  producing  callus,  and  also  from  the  ground  tissue  of 
injured  leaves.  No  definite  outer  form  is  characteristic  of  wound-wood. 
Frost  action  may  kill  the  cambium  in  places,  and  if  the  dead  places  are 
surrounded  by  cushions  of  wound-wood,  then  we  speak  of  frost  canker. 
Frost  cracks  are  filled  with  wound-wood,  which  close  up  the  wound 
followed  by  the  formation  of  a  frost  ridge.  Such  canker  tissue  may  be 
destroyed  during  a  frosty  spell  and  a  new  attempt  to  form  Callus  results 
in  the  addition  of  new  wound-wood  to  the  old  and  frost  cankers  are 
formed. 

Sometimes  without  an  injury,  tissues  resembling  wound-wood  are 
formed  by  the  activity  of  the  normal  cambium,  or  from  a  newly  formed 
independent  cambium.  Under  some  conditions,  the  parenchyma  of 
the  medullary  rays  increases  at  the  expense  of  the  formed  elements  of 
the  wood,  so  that  broadened  medullary  rays  are  formed.  Fasciated 
branches  frequently  show  such  broadened  medullary  rays.  Tuber-like 
gnarls  are  formed  in  fruit  trees  that  have  stone  fruits,  and  also  in 
beech  bark  and  the  structure  of  gnarls  has  been  investigated  by 
Sorauer,  and  the  bark  tubers  of  beech  by  Krick. 


PATHOLOGIC   PLANT   ANATOMY  383 


Wound-cork 


Injury  to  different  plant  organs  such  as  roots,  tubers,  rhizomes, 
stems,  leaves  and  inflorescences  is  followed  by  the  formation  of  cells 
in  rows  and  adjacent  to  the  place  of  injury.  The  walls  of  these  new 
cells  react  to  sulphuric  acid,  chlor-iodide  of  zinc  and  Sudan  III  and  the 
application  of  such  reagents  demonstrates  the  formation  of  cork, 
which  has  been  termed  wound-cork.  It  is  developed  generally  on  all 
parts  of  the  wound,  and  at  its  edges  connects  directly  with  the  normal 
membranes,  thus  closing  the  wound.  The  walls  of  wound-cork  cells 
are  always  thin  and  are  often  folded,  and  the  cork  cells  thus  formed  are 
larger  than  those  of  the  phelloderm.  A  stem  wounded  by  a  knife  cut 
soon  heals  up  unless  disturbed.  The  cut  cells  die,  while  those  next 
below  grow  out  as  a  result  of  the  decreased  pressure,  giving  rise  to  cork 
cells.  As  the  opposing  cushions  of  callus  close  together,  this  cork  is 
squeezed  between  them  and  finally  a  shearing  of  the  cork  cells  results 
as  the  tips  of  callus  close  together  and  unite.  The  only  external  sign 
of  the  wound  is  a  slight  ridge-like  elevation  beneath  which  are  traces 
of  the  dead  cells  and  the  cork  trapped  here  and  there  beneath  the  ridge. 
Normally,  wound-cork  closes  over  the  broken  surface  of  the  scars 
formed  in  the  autumn  by  the  fall  of  the  leaf,  which  is  actually  occasioned 
by  the  formation  of  a  cork  layer,  which  cuts  off  the  leaf  from  the  stem. 


CHAPTER  XXI 
GALLS 

Galls  may  be  defined  as  all  abnormal  tissues  produced  by  the  action 
of  animal,  or  vegetal  parasites.  The  great  majority  of  galls  arise  either 
through  the  growth  of  cells  alone  (gall  hypertrophy),  or  by  cell  division 
(gall  hyperplasia).  The  number  of  galls  constructed  heteroplastically  is 
very  large,  exceeding  the  diverse  gall  hypertrophies.  Galls  of  heteroplastic 
origin  occur  in  the  most  diverse  kinds  of  plants  and  on  all  organs  of  these 
plants.  The  term  gall,  or  cecidium  (cecidia),  is  applied  to  those  varia- 
tions in  form  which  are  caused  by  foreign  organisms.  In  the  forma- 
tion of  the  cecidium,  an  active  participation  of  the  host  plant  is  neces- 
sary and  the  biologic  connection  between  the  host  plant  and  the  gall- 
producing  organism  must  be  considered.  Only  those  cases  fall  within 
our  purview  in  which  abnormal  tissues  are  produced. 

Considered  biologically  and  etiologically  galls  form  a  well-defined 
group  without,  however,  any  one  feature  common  to  all.  Even  when 
considering  only  gall  hyperplasias,  we  will  find  no  common  characteristics 
except  that  a  production  of  heteroplastic  tissue  is  involved  in  all.  This 
is  either  extraordinarily  simple  histologically,  showing  little  or  no  dififer- 
entiation,  or  there  are  specific  differentiations  which  produce  structures 
entirely  distinct  from  those  of  normal  tissues.  The  first  kind  are  cata- 
plasmic  galls,  and  the  second  kind  prosoplasmic.  Galls  may  be  clas- 
sified as  to  their  morphologic  characteristics,  as  well  as  by  their  histolo- 
gic. They  may  be  found  on  every  part  of  plants,  roots,  stem,  branches, 
leaves,  flowers  and  fruits  and  plants  capable  of  producing  galls  belong- 
ing to  all  groups  of  the  plant  kingdom. 

The  following  descriptive  terms  for  galls  will  serve  as  a  rough  clas- 
sification of  their  morphologic  forms.  Connold^  gives  an  example  of 
each  kind. 

As  to  morphologic  character,  galls  are:  axillary,  coalescent,  con- 
glomerate,  cymbiform,  elongated,  globose,  glossy,  gregarious,  hirsute 

1  CoNNOLD,  Edward  T.:  British  Vegetable  Galls,  1901:  24-25. 
384 


GALLS  385 

imbricate,  pedunculate,  pilose,  pubescent,  pustulate,  rugose,  rosaceous, 
scabious,  separate,  sessile,  solitary,  spiny,  rolling  and  thickening  of  the 
leaf,  upon  the  upper  surface  of  the  leaf,  upon  the  under  surface  of  the  leaf, 
upon  the  margins  of  the  leaf.  Some  cecidologists  would  classify  galls 
by  the  causal  animal  or  fungus,  by  the  natural  families  of  the  host 
plants,  according  to  the  situation  of  the  galls  upon  the  plant,  according 
to  their  modes  of  growth,  etc.  Anton  Ke.rner  in  his  "Natural  History 
of  Plants"  (translated  from  the  German  by  F.  W.  Oliver)  divides  galls 
into  simple,  where  one  plant  organ  is  involved,  and  compound,  where 
several  plant  organs  are  concerned  in  their  formation.  The  simple 
galls  he  divides  into  (a)  felt  galls,  (b)  mantle  galls  and  (c)  sohd,  or 
tubicular  galls. 

Cataplasmic  galls  are  often  produced  by  the  action  of  parasitic 
fungi,  which  invade  the  interior  of  the  plant  after  an  infection  by  ani- 
mals, which  by  their  wanderings  over  the  surface  of  the  plant  may  en- 
large the  field  of  their  stimulation.  Domiciled  organisms  are  the  cause 
of  prosoplasms,  where  the  extent  of  the  field  of  stimulation  remains  the 
same  under  all  circumstances,  and  is  effective  only  in  certain  phases  of 
the  development  of  the  host  plants. 

The  etiology  of  galls  is  of  great  interest.  Malpighi  in  his  "  Anatome 
Plantarum"  published  in  1675-79  attributes  the  formation  of  insect 
galls  to  the  action  of  a  poison  excreted  by  the  gall  insect.  Darwin  and 
Hofmeister  explained  galls,  as  the  action  of  different  kinds  of  poisons. 
The  stimuh,  which  cause  the  formation  of  galls,  is  undoubtedly  chemic, 
some  unknown  substances  excreted  by  the  causal  parasite,  excite 
the  cells  of  the  host  plant  to  growth  and  cell  division  and  to  different 
kinds  of  differentiation.  We  know  nothing  definite  about  the  chemic 
substance,  nor  have  the  attempts  to  produce  artificial  galls  been  suc- 
cessful. Traumatic  stimuh,  too,  must  come  into  play,  for  injury  to  the 
plant  goes  hand  in  hand  with  infection,  for  the  first  stage  of  the  develop- 
ment of  galls  resembles  callous  tissue.  The  galls  produced  may  be  due 
to  plants,  phytocecidia,  or  to  animals,  zoocecidia.  The  fungi  and  a  few 
flowering  plants  are  largely  responsible,  while  dipterous  and  hymenop- 
terous  insects  and  mites  are  gall-producing  animals. 

(a)  Cataplasms. — Cataplasmic  galls  are  those  which  are  distin- 
guished from  the  normal  tissue  of  the  corresponding  organs  by  the  small 
amount  of  their  tissue  differentiation.  The  cell  elements  may  often  be 
abnormally  large,  and  the  union  of  these  elements  usually  forms  a  thin- 


386 


GENERAL   PLANT    PATHOLOGY 


Fig    153. — Tubercles  of  velvet  bean  produced  by  inoculation.      {After  Moore,  Geo.  T., 
Yearbook.  Depi.  Agric,  1902,  pi.  xxxvii.) 


GALLS 


387 


walled  often  homogeneous  parenchyma,  while  in  other  cases  the  cata- 
plasms are  marked  by  the  absence  of  any  definite  form,  or  size.  Almost" 
all  phytocecidia,  or  plant-induced  galls,  are  cataplasmic.  The  swell- 
ings on  the  roots  of  various  members  of  the  CRUCiFERiE  caused  by  the 
slime  mould  Plasmodiophora  hrassiccB  are  of  this  nature.  It  is  known 
as  Hanbury,  clubroot,  finger- and- toes  by  the  practical  grower  of 
plants.  Root  nodules,  or  tubercles,  are  produced  on  the  roots  of  legu- 
minous plants  by  bacteria  (Figs.  153,  154,  155,  156),  which  can  utilize 


Fig.    154. —  Cross-section  of  root  tubercle  of  Lupinus  angiislifolius  containing  bac- 
teria,   X  46.      {After  Moore,  Geo.  T.,  Yearbook  Dept.  Agric.  pi.  xxxviii,  1902.) 


free  atmospheric  nitrogen  and  by  their  activity  the  leguminous  plants 
secure  large  amounts  of  nitrogen.  A  species  of  Actinomyces,  or  ray 
fungus,  is  probably  the  cause  of  the  mycodomatia  of  Myrica.  Bacteria 
also  cause  tumors  on  the  Pinus  halepensis  and  Oka  europcea,  on  the  latter 
in  the  nature  of  a  crown  gall  suggested  to  be  somewhat  like  animal 
cancer  (Figs.  157,  158,  159).  Recently  Erwin  F.  Smith  in  relation  to 
the  abnormal  multiplication  of  the  tissues  which  result  in  a  crown- 
gall  tumor,  or  hyperplasia,  concludes  that  the  removal  of  growth  inhibi- 
tions is  brought  about  by  the  physical  action  of  substances  liberated 


388  GENERAL   PLANT   PATHOLOGY 

within  the  tumor  cells  as  the  result  of  the  metabolism  of  the  im- 
prisoned bacteria  iPseudomonas  tumefaciens) .  Growth  of  the  tumor 
comes  about  not  by  the  direct  application  of  stimuh,  but  indirectly 
by  the  removal  of  various  inhibitions.  Under  normal  conditions  the 
physiologic  brakes  are  on  at  all  times,  more  or  less,  in  both  plants 
and  animals,  and  only  when  they  are  entirely  or  largely  removed  in 


■  ■■„,_           *  ■•    1  ■  v. 

^■\   '      '^^m, 

BflfyiP&WSKM                                                            .   f                                                                     t 

%:^^m 

p^p^ 

'  ,;^  .      - 

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Fig,  i,t  t  .o  lcluu  ul  i  ul  luhu  ol  lubcicle  of  Lupinus  aiigustifolius,  con- 
taining bacteria,  X  circa  60.  {AJter  Moore,  Geo.  T.,  Yearbook  U  S.  Dept.  Agric, 
pi.  xxxvtti,  1902  ) 

particular  areas  do  we  observe  an  unlimited  cell  proliferation  result- 
ing in  the  hasty  and  peculiar  growths  known  as  neoplasms,  or  cancers 
(Figs.  158,  159).  Various  weak  (dilute)  poisons  are  known  to  cause 
cell  proliferations  in  plants- — ^that  is,  copper  salts,  ammonia,  salts  of 
lithium,  and  the  excretions  of  the  larvae  of  gall  flies,  of  certain  nema- 
todes and  of  various  fungi. ^ 

The  true  fungi  (EUMYCETES),  including  all  the  important  groups, 
^ Smith,  Erwin  F.:  Mechanism  of  Tumor  Growth  in  Crown  gall.     Journ.  .Vgric. 
Res.  viii:  165-186,  Jan.  29,  1Q17,  with  65  plates. 


GALLS 


389 


form  cataplastic  plant  galls.     Galls  are  due  to  species  of  Synchytrium, 
to  the  aecidial  stage  of  the  rusts  on  violets,  barberries,  nettles  and  buck- 


FiG.  156. — Longitudinal  section  through  red  clover  rootlet,  showing  formation 
of  tubercle,  a,  Rootjhairs;  5,  normal  root  parenchyma;  c,  vascular  tissue;  </,  infected 
areas  showing  infection  strands;  e,  growing  cells  of  tubercle.  (Fig.  44,  page  95, 
Schneider,  Pharmaceutical  Bacteriology,  1912.) 


390 


GENERAL   PLANT   PATHOLOGY 


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[57. — Stem  tumors  on  an  old  apple  tree  at  Mesilla  Park,  N.  Mex.      {After  Hedg- 
cock,  G.  G.,  Circ.  3,   U.  S.  Bureau  of  Plant  Industry,  May  11,  1908.) 


GALLS 


391 


thorns.  Branches  of  Vaccinmm  vitis-idcBa  are  enlarged  by  Calyptospora 
Goeppertiana  and  those  of  Juniperus  and  Chanicecyparis  by  rusts  of  the 
genus  Gymnosporangiiim.  Various  species  of  the  genus  Exobasidium 
produce  soft,  edible  galls.     All  such  galls  are  mycocecidia  (Fig.  84). 

Various  algae,  such  as  Cystoseira  opuntioides,  C.  ericoides,  and  Ecto- 
carpus  Valiantei,  live  parasitically  and  cause  tissue  excrescences,  while 
the  higher  plants,  especially  of  the  family  Loranthace^,  produce  large 
galls  and  the  so-called  wood  roses  on  their  host  plants.  These  wood 
roses  are  formed  by  the  woody  tissues  of  the  host  forming  a  ridge-like 
growth  about  the  clasping  part  of  the  parasite. 

The  animal-produced  galls  known  as 
zoocecidia  are  some  of  them  of  cattiplastic 
nature  and  are  caused  by  nematode  worms, 
insects  and  mites.  The  most  important 
nematode  worm  responsible  for  the  forma- 
tion of  galls  is  Heterodera  radicicola,  which 
attacks  many  cultivated  plants  both  in  the 
greenhouse  and  in  the  open.  The  mite 
galls  include  the  fleshy  (hyperplastic)  curl- 
ings of  the  leaf  edges,  shoot  tips  of  various 
woody  plants.  Erineum  galls,  consisting  of 
multicellular  cones  and  ridges,  are  to  be 
placed  here.  Dipterous  insects  produce 
galls  with  a  prosoplasmatic  structure,  while 
the  cataplasms  produced  by  them  have  the 
form  of  fleshy  curlings  of  the  edges  of  the 
leaves  of  the  host  plants.     Galls  are  produced        Fig.  158. — Crown  gall  on 

also  by  the  attack  of  bugs,  aphids,  or  plant   raspberry.      {After  Conn,  a gri- 
1        ,,  ,  cultural  Bacteriology, -p.  ^06.) 

lice,  leaf  wasps  and  gall  wasps.     They  are 

found  on   roots,   stems,  leaves,  inflorescences  and  fruits.     Such   are 

those  on  the  roots  of  the  grape  due  to  Phylloxera  vastatrix,  etc. 

Histology  of  Cataplasms. — Usually  aside  from  the  slight  tissue 
differentiation  cataplasms  are  composed  of  abnormally  large  cells  with 
an  abundant  protoplasmic  content  and  sometimes  with  red  cell  sap, 
also  a  large  starch  content.  The  primary  and  secondary  tissues  are 
both  involved  in  the  formation  of  the  galls. 

Primary  Tissues. — ^Leaves,  which  are  infected  by  fungi  on  which  are 
formed  mycocecidia,  show  an  arrestment  of  the  tissue  differentiation. 


392 


GENERAL   PLANT   PATHOLOGY 


For  example,  the  distinction  between  the  pahsade  and  spongy  paren- 
chyma is  often  lost,  because  the  palisade  layer  is  not  formed  as  such 
and  sometimes  the  spongy  parenchyma  undergoes  a  rich  proliferation 


Fig.  159.  Section  uf  tobaccu.  Margin  of  infected  needle  wound.  Tumor  in 
middle  part  of  back  parenchyma;  sieve  tubes  at  x.  (After Smith,  Broiun,  McCulloch, 
Bull.  255,  U.  S.  Bureau  of  Plant  Industry,  1912,  pi.  cl.) 

and  red  pigment  sometimes  appears.  The  same  failure  to  form  the  regu- 
lar tissues  is  displayed  by  the  zoocecidia.  The  vascular  and  mechanic 
tissues  may  also  undergo  the  same  reductions  in  cataplasm,  as  do  the 
assimilatory  tissues,  so  that  the  vascular  bundles  in  infected  parts  are 


GALLS  393 

often  only  moderately  developed.  Wakker  describes  the  disappear- 
ance of  the  coUenchyma  in  the  stalks  of  Vaccinium  vitis-idcBa  infected 
with  Exohasidium.  Hyperplastic  excrescences  may  be  found  by  the 
pith  as  in  branches  of  Clematis  attacked  by  jEcidiuni  Englerianum. 

Secondary  Tissues. — Under  this  head  will  be  considered  the  products 
of  the  cambium.  The  formation  of  galls  may  be  due  to  the  division  of 
the  living  derivatives  of  the  already-formed  annual  ring,  or  as  in  wound- 
wood,  its  own  cells  are  used  in  the  production  of  the  cataplasmatic  tis- 
sue. The  wood  and  bark  swellings  formed  by  the  attack  of  animals  and 
fungi  may  be  clustered  or  knob-like  and  resemble  the  frost-induced 
cankers  or  even  the  witches'  brooms. 

Abnormal  wood  found  in  many  woody  galls  is  induced  by  many 
fungi  belonging  to  the  genera  Dasyscypha,  Gymnosporangium  and  Peri- 
dermium,  by  insects,  and  by  parasitic  flowering  plants.  A  character- 
istic feature  of  such  galls  is  the  abnormal  increase  in  the  parenchyma, 
produced  by  the  division  of  the  cambial  derivatives,  which  give  rise  to 
group  of  parenchymatous  cells.  Sometimes  the  cambial  rays  are 
broadened,  so  that  extensive  continuous  masses  of  parenchymatous 
wood  are  produced.  The  same  kind  of  tissue  formation  is  seen  in  an 
examination  of  mycocecidia  and  zoocecidia.  The  mycocecidia  may  be 
illustrated  by  a  brief  consideration  of  the  spindle-like,  or  ball-like, 
woody  galls  induced  on  different  species  of  Juniperus  by  forms  of  the 
genus  of  rust  fungi,  Gymnosporangium.  In  the  diseased  wood,  the 
difference  between  the  spring  and  autumn  wood  is  scarcely  recognizable, 
and  the  parenchyma  occupies  a  relatively  broad  space.  The  cambial 
rays  in  the  parts  of  the  branches  infected  by  Gymnosporangium  clavar- 
iceforme,  instead  of  being  only  two  to  ten  cells  deep,  are  often  ten  to  sixty 
cells  deep  and  at  least  three  cells  broad.  The  woody  gall  of  Gymnospor- 
angium juniperi-virginiancB  shows  still  broader  cambial  rays,  when 
viewed  in  tangential  longitudinal  section.  According  to  the  investi- 
gations of  Reed  and  CrabilV  the  cedar  apple  gall  is  a  modification  of 
the  leaf  of  the  red  cedar  (Fig.  i6o).  The  cedar  leaf  parenchyma  makes 
up  the  greater  portion  of  the  cedar  apple  with  the  fungous  hyphae  in 
the  intercellular  spaces  of  the  parenchyma  cells. 

The  fibro vascular  system  of  the  gall  is  a  modified  continuation  of  the 

1  Reed,  Howard  S.  and  Crabill,  C.  H.:  The  Cedar  Rust  Disease  of  Apples 
Caused  by  Gymnosporangium  Junipcri-Virginiana.  Technical  Bull.  9,  Va.  Agric. 
Exper.  Sta.,  May,  1915. 


394 


GENERAL   PLANT   PATHOLOGY 


fibrovascular  system  of  the  cedar  leaf  (Fig.  i6i).  From,  or  near  the 
base  of  the  cedar  apple,  where  the  vascular  elements  are  much  con- 
torted, arise  many  branches,  which  extend  radially  almost  to  the  cortex. 
Harshberger^  has  investigated  the  galls  produced  by  two  species  of 
Gymnosporangium  on  the  coastal  white  cedar,  ChamcBcyparis  thyoides, 

and  Stewart^  has  published  an 
account  of  the  anatomy  of 
Gymnosporangium  galls  and 
Peridermium  galls. 

There  may  be  an  over-pro- 
duction of  the  wood  paren- 
chyma and  the  parenchymatous 
elements  may  divide  without 
abnormal  widening  of  the 
annual  ring.  The  production 
of  abnormal  resin  canals  which 
are  always  surrounded  with 
parenchyma  illustrate  this 
point.  Hartig  produced  an  in- 
crease of  resin  ducts  in  the  dis- 
eased areas  of  coniferous  trees 
infected  by  Ar miliaria  mellea. 
Abnormal  Bark. — Many  gall 
formations  exist  where  exten- 
sive bark  excrescences  are  pro- 
duced whereby  there  is  an  ab- 
normal formation  of  paren- 
chyma. An  examination  of 
the  galls  due  to  species  of 
Gymnosporangium  shows  that 
the  bark  and  wood  form  excres- 
cences simultaneously.  Wornle  found  that  in  weak  branches  of 
Juniperus  communis  a  rust  fungus,  Gymnosporangium  davaricBforme, 
incited  the  bark  to'  form  woody  parenchyma. 

1  Harshberger,  John  W.:  Two  Fungous  Diseases  of  the  White  Cedar.  Proc. 
Acad.  Nat.  Sci.,  Phila.,  1902:  461-504,  with  2  plates. 

2  Stewart,  Alban:  An  Anatomical  Study  of  Gymnosporangium  Galls.  Amer. 
Journ.  Bot,  ii:  402-417,  October,  1915;  Notes  on  the  Anatomy  of  Peridermium 
Galls,  do,  iii:  12-22,  January,  1916. 


Fig.  160. — Unopened  cedar  apples  on  red 
cedar,  Juniperus  virginiana.  (After  Jones 
and  Bartholomew,  Bull.  257,  Agric.  Exper.  Stat. 
Univ.  Wise,  July,  1915.) 


GALLS  395 

Witches'  Brooms  and  Stag-head. — The  branches  of  the  silver  fir,  the 
flowers,  fruits  and  portions  of  stem  of  various  species  of  plants  are  trans- 
formed into  witches'  brooms,  or  stag-head  by  the  action  of  fungi  of  the 
genus  Exoascus  and  in  the  silver  fir  by  Mcidium  elatinum.     The  shoots 


Fig.  i6i. — Diagram  of  a  longitudinal  section  of  a  cedar  twig  bearing  a  small 
cedar  apple  in  June,  a,  Epidermis  of  cedar  leaf;  b,  sclerenchymatous  layer;  c,  fibro- 
vascular  bundle;  d,  resin  gland;  e,  parenchyma;  /,  parenchyma  of  cedar  apple;  g, 
fibro-vascular  system  of  cedar  apple;  h,  cortex.  (After  Reed,  H.  S.,  and  Crabill, 
C.  H.,  Techn.  Bull.  9,  Va.  Agric.  Exper.  Stat.,  May,  1915.) 

are  annual  instead  of  perennial  and  are  always  sterile  and  branch  out 

into  broom-like,  or  antler-like  forms  called  thunder  bushes  by  some. 

{b)  Prosoplasms.^ — Those  galls  are  included,  as  prosoplasms,  which 

do  not  have  arrested  tissue  dififerentiations,  nor  in  which  callus  tissues 


396  GENERAL   PLANT   PATHOLOGY 

are  found,  but  in  which  new  kinds  of  tissues  are  formed  differing  from 
the  normal  and  in  which  definite  proportions  of  form  and  size  normal  for 
the  species  are  repeated  in  them.  Therefore,  prosoplasms  display  in 
their  external  form,  something  independent  and  well  defined  from  the 
organs  of  the  normal  plant  both  internally  and  externally.  Hyper- 
plastic tissues  of  this  sort  have  been  found  until  now  only  in  the  excres- 
cences caused  by  parasites  and  almost  entirely  those  of  the  animal 
world,  which  produce  zoocecidia.  Six  different  orders  of  insects  are  the 
principal  producers  of  galls  and  various  fungi.  They  are  as  follows: 
The  Acarina,  or  Mites  of  diminutive  size,  produce  galls  of  simple  form 
and  structure. 

The  Diptera,  or  Flies,  cause  many  prosoplasms.  The  galls  produced 
by  the  gall  gnats,  or  gall  midges,  are  very  different  in  character  and  often 
very  complicated. 

The  Hemiptera,  which  include  the  aphides  commonly  known  as 
green  fly  and  plant  lice,  also  produce  numerous  usually  simple  proso- 
plasms. 

The  Hymenoptera,  or  gall-wasps,  produce  striking  galls  on  account 
of  their  size,  diversity  and  complexity  of  form  external  and  internal. 

The  Coleoptera  and  Lepidoptera  (Heterocera)  are  responsible  for 
relatively  few  galls,  and  if  formed  their  structure  is  relatively  simple. 

There  are  several  plant-produced  galls,  or  mycocecidia,  in  which 
there  is  a  regular  arrangement  of  certain  elements  such  as  the  cells  in 
which  anthocyanin  is  formed.  Ustilago  Treuhii  causes  the  production 
of  canker-like  excrescences  on  the  stems  of  Polygonum  chinense,  which 
consist  of  spongy,  parenchymatous,  wood  tissue.  The  excrescences, 
which  develop  from  the  canker  swelling,  are  fleshy,  succulent,  easily 
breakable,  irregularly  bent,  cyhndric  and  often  longitudinally  furrowed 
broadened  at  the  top  Hke  the  head  of  a  snail.  The  fruit  galls,  which 
represent  the  part  which  produces  the  spores  of  the  fungus,  are  repre- 
sented by  this  part  of  the  gall. 

Histology  of  Galls 

Three  types  of  abnormal  cell  divisions,  connected  with  the  formation 
of  galls,  may  be  distinguished,  according  to  the  direction  that  the  di- 
vision takes.  In  the  first  type,  the  regular  orientation  of  the  trans- 
verse partitions  cannot  be  recognized  in  young  galls.  In  the  second 
type,  the  cells  divide  usually  in  a  plane  perpendicular  to  the  upper  sur- 


GALLS  397 

face  of  the  affected  organ.  The  third  type  is  where  no  definite  direction 
of  cell  division  may  be  found. 

The  tissue  material  used  in  the  formation  of  galls  may  be  considered 
from  several  viewpoints.  Thomas  asserts  that  only  those  tissues  are 
able  to  form  galls  which  are  attacked  during  development,  or  in  other 
words  permanent  tissue  cannot  form  galls  and  this  is  certainly  true  of 
prosoplasmatically  formed  galls,  but  with  cataplasms  there  seem  to  be 
exceptions,  where  callus  has  been  formed  from  bark  parenchyma  several 
years  old.  Definite  experimental  proof  of  the  contested  points  cannot 
be  obtained,  because  all  attempts  with  experimentally  producing  cecidia 
have  failed.  It  is  certain,  however,  that  many  galls  are  produced  from 
completely  undifferentiated  tissue,  that  is,  from  the  primary  meristem 
of  the  tips  of  shoots,  or  from  callus  tissue,  but  not  from  cells  and  tissues 
with  lignified  walls.  It  has  been  proved  that  all  living  cells  belonging 
to  the  epidermis,  the  ground  tissue,  or  the  vascular  bundle  tissue,  can 
under  certain  circumstances  participate  in  the  formation  of  galls.  The 
fundamental  tissue,  or  parenchyma,  produces  the  largest  mass  of  the 
galls,  and  it  should  be  remarked  in  passing  that  the  pith,  bark  and 
mesophyll  cells  often  proliferate  with  astonishing  luxuriance.  If  in 
leaf  galls,  for  example,  the  infected  part  of  the  leaf  becomes  ten  or  twelve 
times  the  thickness  of  the  normal  leaf,  it  is  in  nearly  all  case's  the  meso- 
phyll which  has  been  active,  for  in  nearly  all  galls  the  tendency  to  form 
parenchyma  is  striking.  The  epidermis  is  concerned  only  occasionally 
in  the  formation  of  galls  and  the  chlorophyll  content  of  galls  is  scanty. 

The  comparison  of  galls  with  animal  tumors  has  been  made  but  in- 
advisedly because  with  the  exception  of  a  diseased  new  formation  of 
tissue  being  involved  and  in  the  absorption  of  appreciable  amounts  of 
foodstuffs  from  the  fundamental  tissue  galls  and  tumors  have  little  in 
common.  Galls  in  contrast  to  tumors  are  developed  by  a  typic  infection 
growth.  Mixed  swellings  occur  in  galls  where  epidermis,  bark,  meso- 
phyll and  other  tissues  unite  to  form  an  homogeneous  whole  while  no 
tumor  is  known,  which  consists  of  characteristic  tissue  zones  of  such 
diversity  as  those  of  the  galls  of  the  dipterous  insects. 

CECIDIAL  TISSUE  FORMS 

We  are  next  concerned  with  a  study  of  the  different  kinds  of  tissue 
forms  in  galls  and  in  their  consideration  we  will  treat  first  the  two  most 
important,  namely,  the  protective  and  nutritive  tissues. 


398  GENERAL  PLANT   PATHOLOGY 

Protective  Tissues. — The  protective  tissues  of  galls  consist  of  the 
epidermal,  or  covering  tissues,  and  the  stone  cells  which  form  part  of 
the  mechanic  tissue.  The  epidermal  tissue  will  be  considered  as  a  pro- 
tective tissue  irrespective  of  its  origin  whether  from  the  epidermis  of  the 
host,  or  as  a  new  formation.  The  outer  epidermis  of  sac  and  walled 
galls  consists  of  relatively  large,  ofteti  flat  cells  which  have  a  cuticle  of 
moderate  development.  Occasionally  this  epidermis  may  consist  of 
more  than  one  layer.  A  gall  found  on  a  Calif ornian  oak  Quercus  Wisli- 
zeni,  has  the  outer  walls  of  its  epidermal  cells  and  the  upper  part  of  the 
side  walls  thickened  so  that  the  cell  cavity  becomes  conic  in  shape  (Fig. 
162).  Cork,  as  a  covering  for  galls,  is  extremely  rare.  Wound-cork 
is  found  occasionally  in  these  galls,  while  bark  is  even  rarer  in  a  few 
apterous  galls. 

Hair  structures,  or  trichomes,  are  not  unusual  in  galls.  The 
majority  of  prosoplasmatic  galls  are  naked  or  only  slightly  pubescent 
and  some  galls  are  entirely  without  any  covering  tissue. 

Mechanic  Tissue.- — These  consist  of  stereids  (sclerotic,  or  stone  cells) 
or  sclerenchyma  fibers  almost  entirely  and  they  surround  the  larval 
chambers  so  that  their  occupants  are  protected  from  outside  pressure, 
or  sudden  blows.  Lacaze-Duthiers  called  the  stone  cell  tissues  in  galls 
"couche  protectrice."  The  arrangement  of  the  stone  cells,  their 
structure  and  their  position  in  the  gall  tissues  are  of  the  greatest  diver- 
sity. In  the  majority  of  cases,  the  stereids  are  round,  in  other  galls 
they  are  angular,  while  in  others,  they  are  stretched  like  palisade  cells 
and  stand  perpendicular  to  the  upper  surface  of  the  gall  body  similar  to 
those  in  many  fruit  and  seed  shells.  Sometimes  the  sclereid  cell  is  thick- 
ened only  on  one  side,  the  delicately  walled  part  being  outside  as  in  the 
galls  of  Andricus  quadrilineatus  and  sometimes  they  are  inside  as  in  an 
elliptic  gall  of  the  oak,  etc.  The  walls  of  the  sclereids  may  be  pitted, 
and,  therefore,  porous,  while  in  other  cases  the  pitting  may  be  very 
scanty  and  other  peculiarities  have  been  described  by  pathologists 
who  are  intimately  acquainted  with  the  structure  of  galls. 

Nutritive  Tissues.- — The  tissues  of  galls  which  are  eaten  by  the  animal 
occupants  of  the  different  galls,  or  the  contents  of  which  are  beneficial 
to  the  larvae  have  been  termed  by  cecidologists  nutritive  tissues.  The 
position  of  these  nutritive  tissues  in  the  galls  and  their  contents  must 
be  considered  next.  No  gall  is  entirely  without  nutritive  tissues  and 
these  not  infrequently  form  the  largest  part  of  the  gall  and  in  those 


GALLS 


399 


formed  by  dipterous  insects  the  nutritive  layers  are  often  sharply  sepa- 
rated from  the  mechanical  tissue  adjoining.  The  epidermis  of  the  gall 
may  represent  the  nutritive  tissue  when  it  develops  as  an  inner  hairy 
lining  to  the  larval  chamber.  Albuminous  substances  are  found  in  such 
papilla,  or  hairs,  as  well  as  drops  of  fat  and  small  grains  of  starch,  so 
that  the  larvae  are  surrounded  by  abundant  supplies  of  a  rich  pabulum. 
Nutritive  parenchyma  may  be  formed  within  the  mechanic  mantel  and 
here  it  is  available  to  the  larval  occupant  of  the  cell  (Fig.  162).     In 


Fig.  162. —  Cross-section  of  an  un- 
known gall  on  Quercus  Wlslizeni.  Ep, 
pidermis;  Mi,  outer  mechanic  mantle; 
St,  starch-filled  outer  nutritive  layer; 
Ms,  inner  mechanic  mantle.  (After 
Kiister,  p.  252.) 


Fig.  163. — Insect  gall  on  scrub  oak, 
Quercus  nana,  due  to  gall  insect,  Amphi- 
bolips  ilici folia  with  interior  of  gall. 
Pine  Barrens  near  Chatsworth,  N.  J., 
May  27,  1916. 


Other  cases,  the  food  materials  are  stored  outside  the  mechanic  mantel, 
and  they  become  available  only  by  the  larvae  breaking  through  the 
stereid  layer.  The  cells  of  the  nutritive  parenchyma  are  usually  iso- 
diametric,  elongated  and  sac-like  forms,  or  as  delicate  cell  threads.  In 
the  highly  organized  galls  of  the  Cynipidae,  the  cells  of  the  innermost 
layers  on  which  the  larvae  feed  contain  a  cloudy  dense  cytoplasm  in 
which  small  fat  globules  are  seen  and  this  layer  may  be  termed  appro- 
priately the  protein  layer.  A  starch  layer  lies  outside  of  the  protein 
layer.     Here  the  cells  contain  starch.     Besides  the   nutritive  bodies 


400  GENERAL   PLANT   PATHOLOGY 

just  mentioned  occur  tannic  substances  and  lignin  bodies.  The  latter 
are  produced  at  corners  where  several  cells  come  together  as  local 
thickenings  of  the  walls.  It  is  improbable  that  this  lignin  is  nutritive 
in  function. 

Tissues  of  Assimilation.- — Almost  all  galls  are  characterized  by  the 
almost  entire  absence  of  chlorophyll.  In  a  few  galls,  if  present,  the 
chloroplasts  are  small,  twisted  and  feebly  colored  besides  being  extremely 
scanty. 

Vascular  Tissues. — The  tissue  of  galls  is  intimately  associated  with 
the  vascular  bundles  of  the  host  plants  on  which  the  galls  occur  and 
some  are  actually  formed  from  the  tissue  of  the  vascular  bundles.  In- 
side the  galls  the  vascular  strands  are  usually  delicate  cords  both  in 
cataplasms  and  prosoplasms.  Where  they  occur  inside  galls,  we  find 
that  their  individual  elements  resemble  those  of  the  normal  bundles. 
In  a  few  exceptional  cases,  as  in  the  galls  of  Andricus  albopundatus, 
these  are  concentric  bundles.  The  arrangement  of  the  gall  bundles 
varies  greatly  for  we  find  them  in  a  circle,  or  they  pass  through  the  bark 
of  the  gall  as  a  delicate  network. 

Tissues  of  Aeration. — The  structure  of  many  galls  is  an  open  porous 
one  (Fig.  163).  The  gall  parenchyma  cells  in  some  cases  are  star- 
shaped,  fitting  together  by  their  projections,  so  that  large  intercellular 
spaces  are  formed.  Stomata  and  lenticels  constituting  pneumathodes 
are  found  in  galls.  The  stomata,  however,  have  lost  their  ability  to 
close  and  remain,  therefore,  permanently  open.  Lenticels  are  present 
in  some  cases.  The  stomata  and  parts  of  the  epidermis  disintegrate  and 
large  roundish  lenticels  develop  beneath  them.  Perhaps  this  aerating 
tissue  enables  the  larva  to  get  sufficient  oxygen  for  its  metabolism. 
Anthocyanin  is  present  in  the  cells  of  many  galls,  as  their  red  cheeks 
abundantly  testify. 

Secretions  and  Secretory  Reservoirs. — -The  elements  concerned  with 
secretion  in  the  normal  epidermis  are  present  in  galls  in  unchanged  form, 
or  they  are  increased,  richly  furnishing  the  secretions  which  are  asso- 
ciated with  gall  formations.  Less  frequently  new  forms  of  secreting 
cells  and  tissues  are  found  in  galls.  Crystals  of  calcium  oxalate  are  not 
found  usually  in  galls,  but  yet  their  entire  absence  is  a  rare  feature. 
In  some  cases,  the  crystals  when  present  are  associated  with  the  stereids. 

The  presence  of  tannic  bodies  has  been  noted  previously,  and  it 
seems  that  the  tannin  is  found  in  the  cells  of  certain  gall  tissues.     The 


GALLS  401 

outer  cell  layers  in  some  of  the  galls  produced  by  Cynipid.e  is  rich  in 
tannin,  so  that  these  galls  have  been  used  from  time  immemorial  in 
the  tanning  of  leather  and  in  the  production  of  ink.  Tannin  balls  occur 
in  the  nutritive  parenchyma  of  many  galls  and  are  devoured  by  the 
larvie  of  the  same. 

BIBLIOGRAPHY  OF  GALLS 

Adler,  Hermann,  Transl.   b}-   Straton,    Charlks    R.:    Alternating   Generations. 

A  Biological  Study  of  Oak  Galls  and  Gall  Flies.     Oxford,  at  the  Clarendon 

Press,  1894,  pages  198. 
AsHMEAD,  W.  H.:  Galls  of   Florida.     Proc.  Ent.  Spc.  Am.,  new  ser.,  1881:  ix-xx, 

xxiv-xxviii,  1885  and  x-xix.     Trans.  Am.  Ent.  Soc,  xiv:  125—128. 
BEUTENMtJLLER,    WiLLiAM:  Catalogue   of    Gall-producing    Insects    Found    Within 

Fifty  Miles  of  New  York  City,  with  Descriptions  of  Their  Galls,  and  of  Some 

New  Specjes.     Bull.   American  Museum  Natural  History,  iv:  245-278,   with 

8  plates. 
Beutenmuller,  William:  The  Insect  Galls  of   the  Vicinity  of  New  York  City, 

Guide  Leaflet  No.  16,  American  Museum  of  Natural  History.     Reprinted  from 

American  Museum  Journal,  iv.  No.  4. 
CoNNOLD,  Edward  T.:  British  Vegetable  Galls:  an  Introduction  to  Their  Study, 

1902,  pages  312,  with  130  plates. 
Cook,  Mel  T.:  Some  Problems  in  Cecidology.     Botanical  Gazette,  52:  386-390, 

November,  191 1;  A  Common  Error  concerning  Cecidia.     Science,  new  ser.,  34: 

683-684,  Nov.  17,  19 II. 
CosENS,  A.:  A  Contribution  to  the  Morphology  and  Biology  of  Insect  Galls.     Trans. 

Canadian  Institute,  ix:  297-387,  1912,  with  13  plates. 
Darboux,  G.  and  Hovard,  C:  Hilfsbuch  fii.r  das  Sammeln  der  Zoocecidien,  mit 

Beriicksichtigung  der  Nahrpflanzen  Europas  und  des  Mittelmeergebietes. 
Felt,  Efhraim  Porter:  A  Study  of  Gall  Midges  II.     29th  Report  of  the  New 

York  State  Entomologist,  1913:  79-213,  with  16  plates,  Albany,  1915. 
Howard,  C:  Les  Zoocecidies  des  Plantes  d'  Europe  etdu  Bassin  dela  Mediterranee. 

Description    des    Galles.     Illustration.     Bibliographic    detaillee.     Repartition 

geographique.     Index  bibliographique,  2  tomes,  Paris,  1908. 
Kerner,  Anton:  Natural  History  of  Plants,  transl.  by  F.  W'.  Olh-er,  ii:  518-554, 

1895. 
KtJSTER,  Dr.   Ernst:    Die  Gallen   der  Pfianzen.  cin  Lehrbuch  fiir  Botaniker  und 

Entomologen,  mit  158  Abbildungen. 
KtJSTER,  E.:  Pathologische  Pflanzenanatomie,  Gustav  Fischer  in  Jena,  1903;  Zweite 

Auflage,  1916. 
KtJSTER,    E.:  Pathological    Plant    Anatomy,  authorized    translation    by    Fr.xnces 

Dorrance,  19 13-19 1 5. 
L.\caze-Dltthiers,  H.:    Recherches   pour  servir  a  I'historie  des  Galles.     Ann.  Sc. 

Nat.  Eot.,  xii:  353,  1849;  xiv:   17,  1850;  xLx:  273,  332,  1853. 
26 


402  GENERAL   PLANT   PATHOLOGY 

Magnus,  Prof.  Dr.  Werner:  Die  Entstehung  der  Pflanzengallen  verursacht  durch 

Hymenopteren,  Jena,  1914. 
Mayr,  Dr.  GustavL.:  Die  Mittel-Europaischen  Eichen  Gallen  in  Wort  und  Bild, 

Berlin,  1907. 
Osten-Sacken,  C.  R.  von:  On  the  Cynipidae  of  the  United  States  and  Their  Galls. 

Proc.  Ent.  Soc.  Phil.,  I:  47,  62  (1861);  IV:  380  (1865). 
Ross,  Dr.  H.:  Die  Pflanzengallen  (Cecidien)  Mittel-und  Nordeuropas  ihre  Erreger 

und  Biologie  und  Bestimmungs  tabellen,  191 1. 
RtJBSAAMEN,  Ew.  H.:  Die  Zoocecidien  durch  Tiere  erzengte  Pflanzengallen  Deutsch- 

lands  und  ihre  Bewohner,  Leipzig,  191 1. 
Thompson,  Millett  Taylor:  An  Illustrated  Catalogue  of  American  Insect  Galls, 

published  and  distributed  by  Rhode  Island  Hospital  Trust  Co.,  executor  in 

accordance  wdth  the  provisions  of  the  will  of  S.  Millett  Thompson,  edited  by 

E.  Felt,  1915,  pages  66,  with  21  plates. 


CHAPTER  XXXII 
MECHANIC  DEVELOPMENT  OF  PATHOLOGIC  TISSUES 

Our  study  of  plant  pathology  would  not  be  complete  without  a  brief 
reference  to  the  reactions  which  influence  the  genesis  of  the  abnormal 
tissues  of  diseased  plants.  The  investigation  of  these  questions  is  a 
matter  of  recent  development  ever  since  prominence  has  been  given  to 
the  experimental  methods  of  studying  plant  diseases  and  abnormalities. 
Kiister  gives  considerable  prominence  to  these  problems  in  the  second 
edition  of  his  " Pathologische  Pflanzenanatomie"  (pages  328-398), 
where  we  have  the  last  and  most  authoritative  treatment  of  the  subject. 
As  an  important  factor  he  mentions  the  reaction  ability  of  the  living 
cells,  both  in  normal  cell  division  and  with  inequalities  in  cell  division,  for 
it  is  recognized  that  unequal  division  of  the  dividing  cells  plays  an  im- 
portant part  in  pathologic  plant  anatomy.  The  polarity  of  cells  is 
another  important  element  to  be  considered  by  the  pathologic  anatomist, 
for  if  by  unequal  division,  there  is  produced  a  change  in  the  polarity  of 
the  cells  concerned  in  such  division,  the  tissues  which  arise  from  such 
cells  will  show  a  different  kind  of  differentiation. 

Miehe  has  demonstrated  the  physiologic  polarity  of  cells  by  plas- 
molyzing  the  cells  of  a  marine  species  of  Cladophora.  He  found,  after 
the  destruction  of  the  continuity  of  the  protoplasm  from  cell  to  cell  by 
plasmolysis,  and  the  transference  of  the  plant  into  a  solution  of  deter- 
mined concentration,  that  elongated  filaments  developed,  and  that 
rhizoids  developed  from  the  basal  pole  of  each  of  the  cells.  The  epi- 
dermal cells  of  the  leaves  of  linden,  Tilia  platyphylla,  when  attacked  by 
Eriophyes  tilicB  develop  long  cylindric  trichomes  from  the  same  pole 
of  each  cell. 

The  reaction  capabilities  of  the  cells  of  different  tissues  are  both 
quantitative  and  qualitative.  The  cells  of  the  epidermis,  parenchyma, 
sap  bundles  react  differently  and  this  is  expressed  in  the  formation  of 
intumescences,  callus  wound-cork  and  wound-wood  out  of  them. 
The  change  in  the  reaction  of  cells  is  also  a  noteworthy  feature  in  the 
study  of  abnormal  plant  structure.     There  is  a  difference  between  young 

403 


404  GENERAL   PLANT   PATHOLOGY 

organs,  tissues  and  cells,  as  expressed  in  the  growth,  plasticity  and 
processes  of  differentiation  under  the  influence  of  the  exciting  cause,  as 
is  evidenced  in  the  formation  and  nutrition  of  galls  comprehended 
under  the  general  head  of  cecidogenesis. 

The  recent  study  of  the  developmental  mechanics  of  pathologic 
tissues  calls  for  an  investigation  of  stimuli,  and  the  reaction  to  stimuli 
where  every  reaction  presupposes  a  capacity  for  reaction  and  where  the 
cells  of  different  tissues  vary  in  this  respect  and  no  cell  remains  always 
the  same,  but  changes  without  any  influence  of  the  external  world  with 
the  age  of  the  cell,  as  well  as  the  fact  that  every  reaction  presupposes 
previous  conditions  which  permit  the  reaction  to  take  place.  Such 
considerations  as  these  introduce  the  student  to  the  investigation  and 
terminology  of  Roux,  as  set  forth  in  his  "  Terminologie  der  Entwick- 
lungs  Mechanik  der  Tiere  und  Pfianzen,"  191 2,  and  to  the  work  of 
Vochting,  Kiister,  Klebs,  Haberlandt,  N^mec  and  others  along  experi- 
mental lines.  Correlation,  Neoevolution,  Neoepigenesis  are  terms  with 
which  the  pathologic  student  must  become  acquainted.  He  learns  that 
Osmomorphosis  comprehends  all  osmotic  and  turgor  influences  which 
determine  the  form  and  differentiation  of  cells  and  tissues;  that  mechano- 
morphosis  is  where  plant  cells  and  tissues  have  been  modified  in  develop- 
ment by  mechanic  pressure  and  pull;  that  chemomorphosis  is  where 
chemic  influences  are  the  determining  factors  in  molding  the  form  and 
controlhng  the  differentiation  process;  that  trophomorphosis  is  where 
abnormal  nutrition  is  influential  locally  in  the  transformation  of  plants. 

The  consideration  of  chemomorphosis  shows  us  that  we  may  deal 
with  known  chemic  bodies  the  action  of  which  can  be  studied  experimen- 
tally, or  we  may  be  concerned  with  unknown  chemic  substances,  as  the 
poisons  injected  into  the  tissues  of  a  plant  by  the  gall  forms  which  pro- 
foundly influence  the  formation  of  the  gall  tissues. 

Trophic  correlation,  or  trophomorphosis,  exists  between  the  parts  of 
a  cell,  as  well  as  between  the  organs  of  a  plant,  or  the  tissues  of  the 
organs.  The  action  within  the  cell  may  be  between  the  nucleus  and  the 
cytoplasm,  and  its  importance  in  pathologic  plant  anatomy  has  been 
experimentally  studied  by  Gerassimoff  and  N^mec.  Gerassimoff's 
research  dealt  with  the  influence  of  the  size  of  the  nucleus  on  the  cyto- 
plasm, while  N^mec  discovered  that  in  chloralized  roots  of  Viciafaba  the 
cells  with  normal  diploid  chromosome  content  had  didiploid  and  tetra- 
diploid  chromosome-rich  nuclei,  and  that  the  greater  the  content  of  the 


MECHANIC   DEVELOPMENT    OF   PATHOLOGIC   TISSUES  405 

cell  in  nuclear  material  the  greater  becomes  its  volume.  Equally  re- 
markable discoveries  were  made  in  an  investigation  of  the  action  of  tis- 
sues and  organs  upon  one  another.  Vochting  has  produced  a  bending 
growth  in  the  root  of  the  kohlrabi  by  removal  of  the  leaves  of  one 
side  of  the  plant,  so  that  the  development  of  the  normal  side  was 
markedly  greater  than  that  of  the  other.  The  same  effect  was  secured 
in  the  petiole  of  a  compound  leaf  of  Pklea  mollis  by  removal  of  a  lateral 
leaflet  and  the  result  of  this  experiment  is  displayed  in  the  accompany- 
ing figure.  Narcotics  and  the  vitiation  of  the  atmosphere  by  poisonous 
gases  inhibit  growth  in  length.  Mathuse  figures  the  effect  of  removal 
of  the  growing  point  of  a  plant  in  the  promotion  of  superficial  leaf 
growth  and  other  anatomic  changes  in  the  leaves  of  Achyranthes 
VerschafeUii.  Other  experiments  of  a  somewhat  similar  nature  are 
equally  illustrative.  Hardly  a  more  important  and  inviting  field  of 
research  has  been  opened  than  that  which  has  been  revealed  by  the 
investigation  of  the  experimental  plant  morphologists,  or  the  experi- 
mental pathologic  plant  anatomists. 

BIBLIOGRAPHY  OF  DEVELOPMENTAL  MECHANICS 
OF  PATHOLOGIC  TISSUES 

BoRDNEE,  J.  S.:  The  Influence  of  Traction  on  the  Formation  of  Mechanical  Tissue 
in  Stems.     Botanical  Gazette,  48:  251,  1909. 

BucHER,  H.:  Anatomische  Veranderungen  bei  gewaltsamer  Kriimmung  und  geo- 
tropischer  Induktion.     Jahrbucher  ftir  wissenschaftliche  Eotanik,  43:  271,  1906. 

CowLES,  H.  C:  A  Text-book  of  Botany  for  Colleges  and  Universities,  vol.  ii,  Ecol- 
ogy, 1911. 

Daniel,  W.:  Zur  Kenntnis  der  Riesen-  und  Zwergblatter,  Dissertation,  Gottingen, 

1913- 
EwART,  A.  J.  and  Mason- Jones,  A.  J.:  The  Formation  of  Red  Wood  in  Conifers. 

Annals  of  Botany,  20:  201,  1906. 
GoEBEL,  K.:  Organography  of  Plants  (English  edition),  i:  206,  1900. 
H.^BERLANDT,  G.:  Verglcichende  Anatomic  des  assimiherenden   Gewebesystems  der 

Pflanzen.     Jahrbucher  fiir  wissenschaftliche  Botanik,  13:  74,  1882. 
Haberlandt,  G.:  Zur  Physiologic  der  Zellteilung.    Sitzungsber.     Akad.  Wiss.,  Ber- 
lin, 1913,  Nr.  xvi. 
Haberlandt,  G.  transl.  by  Drummond,  Montagu:  Physiological  Plant  Anatomy, 

Macmillan  and  Co.,  London,  1914. 
Hoffmann,  R.:  Untersuchungen  iiber  die  Wirkung  mechanischen  Krafte  auf  die 

Teilung,  Anordnung  und  Ausbildung  der  Zellen  beim  Aufbau  des  Stammes  der 

Laub  und  Nadelholer.     Dissertation,  Berlin,  1885. 
Hartig,  R.:  Das  Rotholz  der  Fichte.  Forstl.  naturwiss.  Zeitschr.,  5:  96,  1896. 


4o6  GENERAL   PLANT   PATHOLOGY 

HiBBARD,  R.  P.:  The  Influence  of  Tension  on  the  Formation  of  Mechanical  Tissue 

in  Plants.     Botanical  Gazette,  43:  361,  1907. 
Keller,  H.:  Ueber  den  Einfluss  von  Belastung  und  Lagelauf  die  Ausbildung  der 

Gewebe  in  Fruchtstielen.     Dissertation,  Kiel,  1904. 
Kny,  L.:  Ueber  den  Einfluss  von  Zug  und  Druck  auf  die  Richtung  der  Scheidewande 

in  sich   teilenden   Pflanzenzellen.     Jahrbiicher  fiir   wissenschaftliche   Botanik, 

37:  55,  94,  1901- 
KiJSTER,  Ernst:  Histologische  und  experimentelle  Untersuchungen  liber  Intumes- 

zenzen.     Flora,  96:  527,  534,  1906. 
KtJSTER,  Ernst-.  Aufgaben  und  Ergebnisse  der  entwickelungsmechanischen   Pflan- 

zenanatomie  Progressus  Rei  Botanicae,  2:  455,  1908. 
KiJsTER,  Ernst:  Gallen  der  Pflanzen,  Leipzig,  191 1. 
MiEHE,  H.:  Wachstum,  Regeneration  und  Polaritat  isoliertcr  Zellen.     Berichte  der 

Deutschen  botanische  Gesellschaft,  23:  257,  1905. 
N£mec,  B.:  Studien  iiber  die  Regeneration,  1905. 
Newcombe,  F.   C.:  The  Regulatory  Formation  of  Mechanical  Tissue.     Botanical 

Gazette,  20:  441,  1895. 
Nordhausen,  Max:  Ueber  Richtung  und  Wachstum  des  Seitenwurzeln  unter  dem 

Einfluss    ausserer    und    innerer    Faktoren.     Jahrbiicher    fiir    wissenschaftliche 

Botanik,  44:  557,  1907. 
Pieters,  A.  J.:  The  Influence  of  Fruit-bearing  on  the  Development  of  Mechanical 

Tissue  in  Some  Fruit  Trees.     Annals  of  Botany,  10:  511,  1896. 
Prein,  R.:  Ueber  den  Einfluss  mechanischer  Hemmung  auf  die  histologische  Ent- 

wicklung  der  Wurzeln.     Dissertation,  Bonn,  1908. 
Roux,  Wilhelm:  Der  Kampf  der  Telle  im  Organisms,  Leipzig,  1881. 
Roux,  Wilhelm;  Terminologie  des  Entwicklungs  mechanik  der  Tiere  und  Pflanzen 

Leipzig,  19 1 2. 
Schulte,    W.:  Ueber    die    Wirkung    der    Ringelung    auf    Blattem.     Dissertation, 

Gottingen,  191 2. 
Simon,   S.:  Experimentelle  Untersuchungen  iiber  die   Entstebung  von   Gefassver- 

bindungen.     Berichte   der   Deutschen   botanische    Gesellschaft,    26:   364,    393, 

1908. 
Smith,   L.    M.:  Beobachtungen   iiber   Regeneration   und  Wachstum  aus  isolierten 

TeLlen  von  Pflanzen  embryonen.     Dissertation,  Hallea  S.,  1907. 
Snow,  L.  M.:  The  Development  of  Root  Hairs.     Botanical  Gazette,  40:  12,  1905. 
Strasburger,  E.:  Ueber  die  Wirkungssphare  der  Kerne  und  die  Zellgrosse  Histo- 
logische Beitr  age,  1893:  5. 
Strasburger,  E.:  Die  Ontogenie  des  Zelle   seit   1875.     Progressus   Rei  Botanicae, 

i:  I,  90,  1907. 
Vochting,  Hermann:  Ueber  die  Bildung  der  Knollen.     Bibliotheca  Botanica,  4:  11, 

1887. 
Vochting,  Hermann:  Untersuchungen  zur  experimentellen  Anatomie  und  Patholo- 
gic des  Pflanzenkorpers,  Tubingen,  1908. 
voN  Schrenk,  H.:  Intumescences  Formed  as  a  Result  of  Chemical  Stimulation. 

Report  Mo.  Bot.  Gard.,  1905:  125. 
WoRGiTzKY,  G.:  Vergleichende  Anatomie  der  Ranken,  Flora,  70:  2-25  etseq.,  1887. 


MECHANIC   DEVELOPMENT    OF   PATHOLOGIC   TISSUES  407 

WoRTMANN,  J.:  Zur  Kenntnis  der  Reizbewegungen,  Botanische  Zeitung,  45:  819, 
1887. 

Suggestions  to  Teachers  and  Students 

The  investigation  of  plant  diseases  in  general  is  most  important  and 
it  should  be  approached  from  a  number  of  standpoints.^  The  teacher  is 
interested  in  it,  because  he  desires  to  arrange  the  subject  matter,  so  that 
it  may  be  presented  in  the  laboratory  and  lecture  course.  The  experi- 
ence of  the  writer  along  these  lines  may  be  of  service  to  other  teachers, 
and  it  is  given,  therefore,  with  some  detail.  Living  plants  should  be 
kept  for  experimentation  along  pathologic  lines.  The  best  plants  for 
this  purpose  will  be  determined  by  the  locality,  by  their  availability,  by 
the  ease  of  their  cultivation  and  by  their  successful  growth  in  the  green- 
house during  the  short  days  of  winter.  The  experiments  outlined  in  the 
lessons  of  part  IV  can  be  tried  upon  these  plants,  such  as  the  influence 
of  chemicals  upon  growth,  the  action  of  illuminating  gas  on  the  health  of 
the  plant,  and  the  extremely  minute,  or  excessive  action  of  amounts  of 
chemic  reagents,  for  some  experiments  conducted  by  Free  at  Johns  Hop- 
kins University  indicate  that  various  plants  react  in  a  specific  way  to 
extreme  dilution  of  poisonous  substances. ^ 

The  plants  can  be  wounded  in  various  ways  and  on  different  organs. 
The  repair  tissue  can  be  studied  by  sectioning  the  healed  part  and  stain- 
ing with  appropriate  stains.  Various  infection  experiments  can  be  tried 
with  fungi  and  the  lesions  produced  can  be  fixed  and  imbedded  in  paraf- 
fin for  sectioning,  mounting,  and  for  study  later  under  the  microscope. 
The  stock  of  such  material  for  study  can  be  increased  materially  by 
collecting  galls,  insect  depredations  on  plants,  examples  of  callus  for- 
mation from  street  trees,  which  have  been  injured  by  horses  biting  off 
the  bark,  or  by  abrasion  with  wagon  wheels.  This  material,  collected 
from  the  streets  and  highways,  from  the  woods  and  fields,  should  be 
fixed  and  hardened  and  finally  embedded  in  paraffin  for  sectioning  and 
microscopic  study.  These  sections  should  be  furnished  along  with 
alcoholic,  or  dried  material  of  the  abnormal  plant,  so  that  the  student 

^  Cf.  Shear,  C.  L.:  Mycology  in  Relation  to  Phytopathology.  Science,  new, 
ser.,  xli:  479-484,  April  2,  1915. 

Smith,  E.  F.:  Plant  Pathology.  Retrospect  and  Prospect.  Science,  new  ser. 
xv:  601-612,  April  18,  1902. 

^Free,  E.  E.:  Symptoms  of  Poisoning  by  Certain  Elements,  in  Pelargonium 
and  other  Plants.  Contributions  to  Plant  Physiology,  The  Johns  Hopkins  Uni- 
versity, March  191 7;  195-198. 


4o8  GENERAL   PLANT   PATHOLOGY 

becomes  familiar  with  the  gross  anatomy,  as  well  as  the  microscopic. 
Photomicrographs  can  be  made  readily  by  the  use  of  the  Edinger  appara- 
tus which  has  been  used  successfully  at  the  University  of  Pennsylvania 
in  class  work.  It  adds  materially  to  the  interest  of  the  work  to  take 
photographs  of  the  sections  studied  and  make  permanent  prints  of  the 
diseased  structures.  After  a  few  years,  the  alcoholic  stock  material 
will  have  increased  to  such  an  extent  that  all  phases  of  pathologic 
plant  anatomy  can  be  demonstrated,  not  only  by  actual  specimens, 
but  also  by  sections.  The  sections,  if  made  directly  by  the  sliding 
microtome,  can  be  kept  in  large  numbers  in  small  bottles  in  50  per 
cent,  alcohol,  where  they  are  available  for  class  use  at  any  time.  The 
paraffin  mounts  can  be  kept  in  block  form  ready  for  use  when  required 
by  the  sequence  of  laboratory  exercises  and  lectures.  If  alcohol  is  not 
available  on  account  of  its  high  price,  other  materials  may  be  used  in  its 
place. 

The  sections  and  alcoholic  material  having  been  prepared  for  use 
can  be  studied  for  hypertrophy,  for  metaplasia,  hypoplasia  and  other 
pathologic  conditions.  Such  an  investigation  presupposes  a  thorough 
grounding  in  the  technique  of  plant  anatomy  and  histology,  so  that  no 
time  may  be  wasted  in  unnecessary  explanations.  From  the  stand- 
point of  curriculum,  such  a  course  in  mycology  and  pathologic  plant 
anatomy  should  be  given  in  the  junior,  or  senior  years,  or  deferred  until 
the  post-graduate  years  because  of  the  special  nature  of  the  work. 

Written  reports  should  be  required  of  all  students  based  upon  the 
experiments  with  the  inoculation  and  infection  of  various  cultivated 
plants  and  their  reaction  to  various  fungi.  Similarly,  where  pathologic 
anatomy  and  histology  of  plant  organs  and  tissues  are  concerned  photo- 
graphic prints  may  take  the  place  of  microscopic  drawings.  Each 
topic  considered  in  the  lecture  course  should  receive  attention  in  the 
laboratory  and  in  the  field  and  indoor  experiments,  because  this  work 
is  designed  to  prepare  future  plant  doctors,  teachers  and  investigators, 
who  are  interested  in  the  science  of  phytopathology  and  who  are 
anxious  to  be  proficient  in  the  study  of  plant  diseases. 

Stock  material  should  be  kept  of  all  the  more  common  insect  and 
fungous  diseases  of  cultivated  and  wild  plants  not  only  for  such  patho- 
logic study,  but  also  for  a  systematic  and  morphologic  work  with  insect 
and  fungous  parasites.  The  mycologic  student  should  be  able  to 
identify  not  only  the  more  common  insects  and  fungi  after  such  a 


MECHANIC    DEVELOPMENT    OF    PATHOLOGIC    TISSUES  409 

course,  but  should  be  able  also  to  diagnose  the  more  common  diseases 
and  suggest  remedies  in  the  form  of  insecticides,  or  fungicides,  or  other 
remedial  measures  from  a  knowledge  of  the  physiology  of  pathologic 
plants.  A  change  in  the  soil,  or  a  change  in  the  temperature  and 
exposure  may  be  all  that  is  needed  to  keep  a  plant  in  a  perfect  state 
of  health. 

The  problems  which  may  be  assigned  to  the  post-graduate  student 
for  experimental  investigation  are  unlimited  in  America,  where  the 
nation  is  confronted  by  serious  pests  introduced  from  various  lands. 
The  anatomic  and  histologic  characters  and  the  development  of  cecidia 
have  been  the  subject  of  extensive  studies  in  Europe,  but  American 
botanists  have  done  very  little  in  the  study  of  American  galls  along  these 
lines  of  investigation.  The  character  of  the  poisons  which  cause 
the  stimulation  of  the  plant  to  produce  the  galls  is  a  matter  well  worth 
the  attention  of  botanists  experimentally  inclined.  The  equipment  of 
the  laboratory  and  the  facilities  for  experimentation  should  be  con- 
sidered before  the  problem  is  assigned  to  the  post-graduate  student. 
The  previous  training  and  bias  of  the  individual  should  be  weighed 
carefully  for  the  research  work  may  be  of  a  cytologic  nature.  It  may  be 
a  histologic  study  pure  and  simple  with  pathologic  tissues,  or  the  prob- 
lem may  deal  with  prophylaxis,  or  preventive  measures.  It  may  be 
that  the  student  is  better  prepared  to  investigate  the  etiology  of  disease, 
or  the  composition  of  sprays  and  their  effects  on  the  plant  tissues. 
Some  advanced  students  would  find  keener  zest  in  the  systematic  or 
biologic  study  of  some  fungus,  or  group  of  fungi,  or  the  bias  may  be 
toward  detailed  experimentation  with  insects,  or  other  forms  of  animal 
life.  The  teacher  should  weigh  carefully  all  of  these  details  and  act 
accordingly.  Problems  with  an  economic  bearing  would  be  more  suit- 
able for  the  students  of  agricultural  colleges  and  experiment  stations, 
while  matters  of  pure  science  might  be  properly  relegated  to  the 
endowed  colleges  and  universities,  where  investigation  with  a  practical 
trend  would  not  be  absolutely  essential.  The  laboratory  work  should 
be  combined  with  field  work  in  the  study  of  inorganic  and  organic  dis- 
eases. The  character  of  the  field  work  will  be  determined  by  the 
nature  of  the  investigation  and  by  the  season  and  by  the  climatic  con- 
ditions. The  work  in  the  field  at  first  would  consist  in  the  observation 
of  diseases,  the  taking  of  notes  from  the  living  trees  and  the  collection  of 
material  for  more  detailed  study.     The  extent  of  the  injury  should  be 


4IO  GENERAL   PLANT   PATHOLOGY 

determined.  Extension  and  the  work  of  prevention  can  be  carried  on. 
Cooperative  work  with  the  progressive  farmers  and  horticulturists  can 
be  inaugurated  with  profit  to  the  farmer  and  the  investigator.  The 
etiology  of  diseases  can  be  investigated  by  properly  directed  field  experi- 
ments. Inoculations  can  be  made  on  plants  growing  in  the  field,  or  in 
the  laboratory  or  greenhouse.^  Such  original  investigation  presup- 
poses the  accumulation  of  apparatus  and  a  suitable  working  library. 
With  the  limited  appropriation  available  for  the  purchase  of  apparatus 
and  books,  such  an  equipment  seems  beyond  the  ordinary  school  and 
college,  but  it  will  be  surprising  to  those  who  have  not  tried  the  plan  how 
many  books,  diagrams,  etc.,  can  be  accumulated,  and  how  much 
apparatus  can  be  secured  by  spreading  the  purchase  of  such  needful 
things  over  a  series  of  years.  If  the  books  and  apparatus  are  cared  for, 
little  deterioration  need  be  suffered  and  at  the  end  of  twenty  or  twenty- 
five  years,  a  respectable  stock  of  these  desiderata  will  be  on  hand  for  use 
in  the  class  room,  laboratory,  research  rooms  and  greenhouses. 

The  growth  of  the  study  of  plant  pathology  as  a  distinct  branch 
of  science  has  been  by  leaps  and  bounds.  It  is  now  on  a  more  satisfac- 
tory basis  than  ever  before,  and  a  larger  number  of  men  and  women  are 
directing  their  attention  to  phytopathology  as  a  life  work.  The  men 
who  enter  this  field  from  now  on  must  have  a  better  and  an  all-sided 
training.  This  presupposes  an  acquaintance  with  the  literature  of  the 
subject  in  his  own  and  several  foreign  languages.  There  should  also  be  a 
training  in  chemistry  and  physics.  He  should  know  something  about 
zoology  and  should  be  conversant  with  the  physiology  and  histology  of 
plants  and  other  phases  of  botanic  inquiry.  To  meet  this  demand  our 
American  colleges  and  universities  have  introduced  subjects  which  will 
be  of  direct  benefit  to  the  future  plant  pathologist.  The  curricula^ 
have  been  arranged  to  introduce  the  study,  hot  only  of  plant  pathology, 
but  also  cognate  subjects  some  of  which  may  not  have  a  direct  bearing, 
but  which  make  the  man  a  well-trained  and  a  competent  "plant 
doctor." 

iC/.  Heald,  F.  D.:  Field  Work  in  Plant  Pathology.  The  Plant  World,  lo: 
104-109,  May,  1907. 

2  Fink,  Bruce:  A  College  Course  in  Plant  Pathology.  Phytopathology,  II: 
150-152,  August,  1912.  Consult  Stevens,  F.  L.:  Problems  of  Plant  Pathology, 
The  Botanical  Gazette,  Ixiii:  297-306,  Apr.,  191 7;  also  Harshberger,  John 
W. :  The  Need  of  Competent  Plant  Doctors,  Education,  1895,  140-144. 


PART  III 
SPECIAL  PLANT  PATHOLOGY 

CHAPTER  XXXIII 
LIST  OF  SPECIFIC  DISEASES  OF  PLANTS 

The  remarkable  growth  of  the  work  of  the  United  States  Depart- 
ment of  Agriculture,  and  that  of  the  agricultural  experiment  stations  of 
the  different  states,  has  been  along  the  most  diverse  lines.  Mycology 
has  been  given  prominence  and  the  number  of  trained  workers  in  this 
field  has  increased  to  such  an  extent,  that  a  separate  organization, 
known  as  the  American  Phytopathological  Society,  has  been  found 
necessary.  The  meetings  of  this  society  have  been  largely  attended 
and  the  papers  read  have  been  of  the  greatest  value  and  interest.  The 
organ  of  the  society,  "Phytopathology,"  has  published  already  a  con- 
siderable number  of  important  papers,  and  it  has  set  a  high  standard  for 
the  future  work  along  mycologic  and  pathologic  lines.  One  of  the 
specific  problems,  which  it  has  attempted  to  do  through  special  com- 
mittes  appointed  for  the  purposes,  has  been  to  suggest  the  use  of  com- 
mon names  of  fungous  diseases  based  on  recognized  rules  of  procedure 
and  to  prepare  a  list  of  the  common  and  important  diseases  of  economic 
plants  in  the  United  States  and  Canada.  The  preliminary  report  of 
the  committee  on  common  names  has  been  made,  but  considerable 
time  must  elapse  before  the  list  of  common  and  important  diseases  is 
completed. 

As  this  book  will  be  printed  and  issued  before  the  preliminary  list  of 
the  American  Phytopathological  Society  of  fungous  diseases  appears, 
it  has  been  deemed  advisable  to  compile  a  list  from  various  sources  of 
information  for  the  common  host  plants  in  the  United  States  and 
Canada,  using  the  "Literature  of  Plant  Diseases"  given  by  W.  C. 
Sturgis  in  the  Report  of  the  Connecticut  Agricultural  Experiment 
Station  for  the  year  ending  Oct.  31,  1900,  part  III,  pages  255-293,  as 
the  basis  of  such  a  list. 

411 


412  SPECIAL   PLANT   PATHOLOGY 

That  the  list  might  be  made  as  complete  as  possible  and  repre- 
sentative of  the  plant  diseases  of  the  United  States  and  the  tropic 
countries  to  the  southward,  the  following  publications  have  been 
used  in  its  compilation. 

Atkinson,  Geo.  F.:  Studies  of  Some  Shade  Tree  and   Timber-destroying    Fungi. 

Cornell  Univ.  Agric.  Exper.  Sta.,  Bull.  193,  June,  iqoi. 
CoiT,  J.  E.:  Citrus  Fruits,  1915:  364-402,  The  Macmillan  Co. 
Cook,  Melville  T.:  The  Diseases  of  Tropical  Plants,  1913,  The  Macmillan  Co. 
DuGGAR,  Benj.  M.:  Fungous  Diseases  of  Plants,  1909,  Ginn  and  Co. 
Freeman,  E.  M.:  Minnesota  Plant  Diseases,  1905. 
Graves,  Arthur  H.:  Notes  on  Diseases  of  Trees  in  the  Southern  Appalachians. 

Phytopathology,  III  (1913)  and  IV  (1914). 
Heald,  Fredk.  D.  and  Wolf,  Fredk.  A.:  A  Plant-disease  Survey  in  the  Vicinity 

of  San  Antonio,  Texas.     U.  S.  Bureau  of  Plant  Industry,  Bull.  226,  191 2. 
Hesler,  Lex  R.  and   Whetzel,  Herbert  H.:  Manual  of  First  Diseases,     xx + 

146  pages,  126  figs.,  191 7,  The  Macmillan  Co. 
HuME,H.  Harold:  Citrus  Fruits  and  Their  Culture,  191 1:  466-492,  Orange  Judd  Co. 
Jackson,  H.  S.:  Some  Important  Plant  Diseases  of  Oregon  in  Biennial  Crop  Pest 

and  Horticultural  Report,  1911-1912,  Oregon  Agric.  E.xper.  Sta.,  177-308. 
Longyear,  B.  O.:  Fungous  Diseases  of  Fruits  in  Michigan.     Michigan  State  Agric. 

Coll.  Exper.  Sta.,  Special  Bull.  No.  25,  March,  1904. 
Meinecke,  E.  p.:  Forest  Tree  Diseases  Common  in  California  and  Nevada.     U.  S. 

Forest  Service,  A  Manual  for  Field  Use,  1914. 
Reed,  Howard  S.  and  Cooley,  J.  S.:  Plant  Diseases  in  Virginia  in  the  Years  1909 

and  1910. 
RoBBiNS,   W.   W.   and  Reinking,   Otto  A.:  Fungous  Diseases  of   Colorado   Crop 

Plants.     Agric.  Exper.  Sta.  Colo.  Agric.  Coll.,  Bull.  212,  October,  191 5. 
Selby,  a.  D.:  a  Brief  Handbook  of  the  Diseases  of  Cultivated  Plants  in  Ohio, 

Bull.  214,  Ohio  Agric.  Exper.  Sta.,  1910. 
Shear,  C.  L.  and  Wood,  Anna  K.:  Studies  of  Fungous  Parasites  Belonging  to  the 

Genus  Glomerella.     U.  S.  Bureau  of  Plant  Industry,  Bull.  252,  1913. 
Smith,  Ralph  E.  and  Smith,  Elizabeth  H.:  California  Plant  Diseases.     Coll.  of 

Agric,  Agric.  Exper.  Sta.,  Bull.  218,  June,  1911. 
Stevens,   F.  L.   and  Hall,   J.   G.:  Diseases  of  Economic  Plants,  1910,  The  Mac- 
millan Co. 
von  Schrenk,  Hermann:  Some  Diseases  of  New  England  Conifers.     U.  S.  Div.  Veg. 

Physiol,  and  Pathol.,  BuU.  25. 
von  Schrenk,  Hermann:  Sap-rot  and  Other  Diseases  of   the  Red   Gum.     U.  S. 

Bureau  of  Plant  Industry,  Bull.  114,  1907. 
von  Schrenk,  Hermann  and  Spaulding,  Perley:  Diseases  of  Deciduous  Forest 

Trees.     U.  S.  Department  of  Plant  Industry,  Bull.  149,  1909. 
Whetzel,  H.  H.  and  Rosenbaum,  J.:  The  Diseases  of  Ginseng  and  Their  Control. 

U.  S.  Bureau  of  Plant  Industry,  Bull.  250,  191 2. 

This  list  will  serve  as  an  index  of  the  diseases  which  will  be  described 


LIST   OF    SPECIFIC   DISEASES    OF   PLANTS  413 

in  full  in  the  remainder  of  part  III.  As  it  will  be  impossible  to  describe 
in  detail  all  of  the  diseases  of  the  list,  a  selected  number  will  be  chosen, 
which  will  illustrate  the  subject  and  which,  if  mastered  by  the  student, 
will  lay  the  foundation  for  a  more  thorough  acquaintance  with  the 
diseases,  which  are  prevalent  in  the  United  States,  and  which  the 
student,  the  teacher,  the  horticulturist,  the  forester,  the  agriculturist, 
and  the  practical  mycologist  are  likely  to  meet  in  their  plant-growing 
experience.  It  is  recommended  that  for  each  of  the  diseases  described 
in  the  following  pages  the  outline  for  the  use  of  students  given  in 
Lesson  29  be  used  to  facilitate  an  investigation  of  the  disease  in  the 
laboratory,  greenhouse,  or  in  the  open  field.  This  is  a  method  of 
study  approved  by  the  best  teachers  of  the  United  States. ^  The  author 
wishes  to  state  emphatically  that  he  has  designedly  kept  down  the 
number  of  diseases  described  in  the  following  pages  because  the 
thorough  mastery  of  a  limited  number  is  better  than  a  superficial  study 
of  a  larger  list. 

The  general  list  precedes  the  descriptive  pages  of  part  III  dealing 
with  a  series  of  specific  plant  diseases,  especially  chosen  because  of  the 
author's  familiarity  with  them,  or  because,  they  stand  out  prominently 
as  some  of  the  more  important  diseases,  which  concern  the  American 
plant-grower. 

These  specific  diseases  are  divided  into  two  groups.  One  group 
includes  the  parasitic  diseases  due  to  fungi  as  the  causal  organisms.  The 
other  group  includes  the  non-parasitic,  or  so-called  physiologic  diseases 
of  plants.  These  have  been  treated  in  general  in  part  II  of  this  book, 
but  certain  of  the  non-parasitic  diseases  have  become  of  such  general 
interest  that  they  merit  a  more  detailed  treatment.  The  literature  of 
these  diseases  is  very  much  scattered,  the  only  general  account  being 
one  published  by  Sorauer,  Lindau  and  Reh  in  their  "Handbuch  der 
Pfianzenkrankheiten"  (3d  Edition  of  Sorauer),  1908.  This  work  is  be- 
ing translated  by  Frances  Dorrance.  Four  parts  of  Vol.  I  have  been 
printed  and  the  other  parts  will  appear  as  fast  as  translated  and  printed. 
The  English  edition  beginning  1914  is  entitled  "Manual  of  Plant  Dis- 
eases." To  this  work  the  student  of  plant  pathology  is  referred  for 
many  details. 

1  Whetzel,  H.  H.  and  Collaborators:  Laboratory  Exercises  in  Plant 
Pathology,  Ithaca,  N.  Y.,  1916. 


414  SPECIAL  PLANT   PATHOLOGY 

Parasitic  Diseases  of  Plants 

A  LIST  OF  THE  COMMON  AND  IMPORTANT  DISEASES  OF  ECONOMIC 
PLANTS  IN  THE  UNITED  STATES  AND  CANADA 

Alfalfa 

{Medicago  saliva,  L.) 

Anthracnose  {CoUetotrichum  trifolii,  Bain). 

Journ.  MycoL,  Vol.  XII,  p.  192  (1906). 
Bacterial  Blight  {Psendomonas  mcdicaginis  Sacket). 

Bull.  212,  Colo.  Agr.  Exp.  Sta.  (October,  1915). 
Downy  Mildew  (Peronospora  trifoliorum,  de  By.). 

N.  Y.  Agr.  E.xp.  Sta.,  Bull.  305,  p.  394  (1908). 
Leaf -blotch  {Pyrenopeziza  medicaglnis,  Fckl.). 

Phytopathology  6,  Abstracts  of  Columbus  Meeting. 
Leaf -spot  {Pseudopesiza  medicaginis  (Lib.),  Sacc). 

Ibid.,  p.  384. 
Root-gall  {Urophlyciis  alfalfa;  (v.  Lagerh.),  Magn.). 

Duggar,  Fungous  Diseases  of  Plants,  p.  140  (1909). 
Texas  Root-rot  {Ozonium  omnivorum,  Shear.) 

Tex.  Agr.  Exp.  Sta.,  Bull.  22  (1892). 
Rust  {Uromyces  slriatus  Schrot). 

Bull.  218,  Calif.  Exp.  Sta.  (June,  191 1). 

Iowa  Bull.  131,  p.  209  (April,  1912). 
Violet  Root-rot  {Rhizodonia  crocorum  (Pers.)  DC.).- 

Phytopathology  i,  p.  103  (1911). 
Winter  Injury. 

N.  Y.  (Cornell)  Agr.  Exp.  Sta.,  Bull.  221,  p.  6  (1904). 

Almond 
{Prunus  amygdalus,  Baill.) 

Armillaria  Root- Rot  {Annillaria  mellea,  Vahl.). 

Cal.  Agr.  Exp.  Sta.,  Bull.  218,  p.  1084  (191 1). 
Crown-gall  {P seudomonas  tiimefaciens,  E.  F.  Sm.  &  Towns). 

Ariz.  Agr.  Exp.  Sta.,  Bull.  t,t,  (1900). 
Die-back  [N on- par.). 

Cal.  Agr.  E.xp.  Sta.,  Bull.  218,  p.  1086  (1911). 
Rust  {Puccinia  pruni-spinosm  Pers.). 

Duggar,  Fungous  Diseases  of  Plants,  p.  417  (1909). 
Shot-hole  (Cercospora  circumcissa,  Sacc). 

Journ.  MycoL,  Vol.  VII,  p.  66  (1892). 

Ampelopsis 

Leaf-spot  {Phyllosticla  ampelopsidls,  Ell.  &  Mart,  Laestadia  BidweUii  (Ell.)  V.  &  R. 
and  SphcEropsis  hedericola  (Speg.). 


LIST   OF    SPECIFIC   DISEASES    OF   PLANTS  415 


N.  J.  Exp.  Sta.,  Rep.  (1914). 
Die-back  {Cladosporium  sp.). 

N.  J.  Exp.  Sta.  Rep.  (1914). 

Apple 

{Pirus  mains,  L.) 

Anthracnose  {Gleosporium  malicorticis,  Cordley;  Ascigerous  stage  said  to  be  Neofab. 
rcea  malicorticis  (Cordley)  Jackson,  see  Phytopathology  2:  94,  1912). 

Oregon  Sta.,  Biennial  Rep.,  pp.  178-197  (1911-12). 
Arsenical  Poisoning. 

Cal.  Agr.  Exp.  Sta.,  Bull.  131  (1908). 
Bark-canker  (Myxosporium  corticolum,  Edg.). 

Ann  Myc,  Vol.  VI,  p.  48  (1908). 
Bitter-rot  (Glomerella  riifomaculans  (Berk.)  Spauld.  &  v.  Schr.).' 

Bitter-rot  canker,  U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  44  (1903). 
Black-rot  {Sphceropsis  malornm,  Berk.). 

Black-rot  Canker. 

N.  Y.  State  Agr.  Exp.  Sta.,  Bull.  163  (1899). 

Black-rot  Leaf-spot. 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  121,  p.  47  (1908). 
Blight  (Bacillus  amylovorus  (Burr.),  Trev.). 

Blight-canker,  N.  Y.  (Cornell)  Agr.  Exp.  Sta.,  Bull.  236  (1906). 

Blossom- blight.  Phytopathology,  Vol.  IV,  p.  27  (1914). 

Collar-blight,  Penn.  Agr.  Exp.  Sta.,  Bull.  136,  p.  7  (1915). 

Fruit-blight,  Ibid.,  p.  20. 

Twig-blight,  N.  Y.  (Cornell)  Agr.  Exp.  Sta.,  Bull.  329,  p.  322  (1913). 
Blister-canker  {Nummularia  discreta  (Schw.)  Tul.). 

111.  Agr.  Exp.  Sta.,  Bull.  70  (1902). 
Blotch  {Phylloslicta  solitaria,  Ell.  &  Ev.). 

Blotch  canker,  U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  144,  p.  10  (1909). 

Blotch  leaf-spot.  Ibid.,  p.  11. 

Fruit-blotch,  Ibid.,  p.  9. 
Blossom  End  Rot  (Alternaria  sp.). 

N.  J.  Exp.  Sta.  Rep.,  p.  471  (1914). 
Blue  Mold  Rot  (Penicillium  spp.). 

Stevens  Diseases  of  Economic  Plants,  p.  94  (1913). 
Brown-rot^  {Sclerotinia  frucligena  (Pers.)  Schrot.). 
Stevens  and  Hall;  Diseases  of  Economic  Plants,  p.  92  (1913). 
Canker  (Pacific  Coast)  {Macrophoma  curvispora,  Pk.). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  83  (1913). 
Common  Rust  {Gymnosporangium  juniperi-virginlance,  Schw.). 

U.  S.  Dept.  Agr.,  Rep.,  1888,  p.  376  (1889). 
1  Consult  Shear,  C.  L.  and  Wood,  Anna  K:  Studies  of  Fungous  Parasites  Belong- 
ing to  the  Genus  Glomerella.     U.  S.  Bureau  of  Plant  Industry,  Bull.  252,  1913. 

^For  apple  rots  consult  Phytopathology  4,  p.  403,  December,  1914,  and  Manual 
of  Fruit  Diseases  by  Hesler  and  Whetzel. 


41 6  SPECIAL   PLANT  PATHOLOGY 

Crown-gall  (Pscitdomonas  tumefaciens,  E.  F.  Sm.  &  Towns). 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  i86,  p.  13  (1910). 

Hairy-root,  Ibid.,  p.  14. 
Fly-speck  {Leptothyrium  pomi  (Mont.  &  Fr.),  Sacc). 

Ohio  x\gr.  Exp.  Sta.,  Bull.  79,  p.  133  (1897). 
Frost-blister  (N on- par.). 

N.  Y.  Agr.  Exp.  Sta.,  Bull.  220  (1902). 
Frog-eye  Spot  {PhyUosticta  pirina  Sacc.) 

Va.  Rep.,  pp.  95-115,  figs.  16  (1911-12). 
Fruit-pit  {Non-par.). 

Bull.,  Torr.  Bot.  Club,  Vol.  XXXV,  p.  430  (1908). 
i Phyllachora  pomigena  (Sch-w.),  SsLCC. 
Fruit-spot      {Phonia  pomi,  Pass.  (Phytopath.,  Vol.  II,  pp.  63-72). 
[Sphceropsis  malorum,  Pk. 

Bull.  121,  U.  S.  Bureau  PI.  Indst. 
Leaf -spot  (Frog-eye)  {PhyUosticta  pirina,  Sacc). 

R.  I.  Agr.  Exp.  Sta.,  Rep.  7,  pp.  188-192  (1895). 
Pink-rot  {Cephalothecium  roseum,  Cda.). 

N.  Y.  Agr.  E.xp.  Sta.,  Bull.  227  (1902). 
Powdery  Mildew  {Podosphcera  leucotricha  (Ell.  &  Ev.)  Salm.  and  P.  oxyacantlicp  {DC.) 
deBy.). 

U.  S.  Dept.  Agr.,  Bull.  120  (1914). 
Ripe-rot  {Glcosporium  fructigenum,  Berk). 

Journ.  Mycol.,  Vol.  VI,  pp.  164,  172  (1891). 
Root-rot  {Armillaria  mcllea  Vahl). 

Oregon  State  Biennial  Report,  pp.  226-233  (1911-12). 
Scab  {Venturia  inaequalis  (Cke.),  Wint.). 

N.  Y.  (CorneU)  Agr.  Exp.  Sta.,  Bull.  335  (1913). 

Mont.  Bull.  96,  pp.  65-102,  pi.  I,  figs.  3  (February,  1914). 
Scab  {Fusicladimn  dendriticiim  (Wallr.)  Fckl.) 

Wash.  Bull.  64,  pp.  24,  pis.  2,  figs.  5  (1904). 
Rusts  {GymtiosporangimnJHniperi.virginiancB  Schw.  {Rmstelia  pi  rata  (Schw.),  Thaxt.); 

G.  globosum,  Farl.  {Ra'stclia  laccrata,  y,  z.  Thaxt.). 
Scald  {Non-par.). 

Vt.  Agr.  Exp.  Sta.,  Rep.  10,  p.  55  (1897). 
Scurf  {PhyUosticta  prunicola  (Opiz),  Sacc). 

Stevens  &  Hall,  Disease  of  Economic  Plants,  p.  78  (191 1). 
Silver-leaf  {Stercum  purpureum,  Pers.). 

Phytopathology  i,  p.  177  (1911). 
Sooty-blotch  {Leptothyrium  pomi  (Mont.  &  Fr.),  Sacc). 

Duggar,  Fungous  Diseases  of  Plants,  p.  367  (1909). 
Spongy  Dry-rot  {VolutcUa  friicti,  Stev.  &  Hall). 

Duggar,  Fungous  Diseases  of  Plants,  p.  316  (1909). 
Spray  Injury  {N on- par.). 

Bordeaux  injury,  N.  Y.  Agr.  Exp.  Sta.,  Bull,  287  (1907). 

Lime-sulphur  injury,  Ore.  Agr.  Exp.  Sta.,  Research  Bull.  2  (1913). 


LIST   OF    SPECIFIC   DISEASES    OF   PLANTS  417 

Stem-blight  {Pseiidomonas  mcdicaginis,  Sackett.) 

Col.  Bull.  158,  April,  1910,  pp.  3-32;  Bull.  159,  pp.  3-15  (April,  1910). 
Stem-rot  {Schizopkylliim  commune  Fr.) 

Bull.  218,  Calif.  Agr.  Exp.  Sta.  (June,  191 1). 
Volutella  Rot  {Voluidla  fritcti,  Stev.  &  Hall). 

N.  C.  Agr.  Exp.  Sta.,  Bull.  196,  pp.  41-48  (1907). 
Water-core  (Non-par.). 

Phytopathology  3,  p.  121  (1913). 
Winter  Injury  (Non-par.). 

Winter  bark-splitting,  Canada  Exp.  Farm.  Rep.,  1908,  p.  112  (190S). 

Winter  black  heart.  Ibid.,  p.  113. 

Winter  bud-injury,  Mont.  Agr.  Exp.  Sta.,  Bull.  91  (191 2). 

Winter  crotch-injury.  Me.  Agr.  E.xp.  Sta.,  Bull.  164,  p.  17  (1909). 

Winter  crown-rot,  N.  Y.  Agr.  Exp.  Sta.,  Techn.  Bull.  12,  p.  370  (1909) 

Winter  die-back,  Canada  Exp.  Farms,  Rep.,  1904,  p.  108;  1908,  p.  113. 

Winter  root-injurj^  Iowa  Agr.  Exp.  Sta.,  Bull.  44,  p.  180  (1899). 

Winter  sunscald,  Canada  Exp.  Farm  Rep.,  p.  112  (1908). 

Apricot 
(Primus  armeniaca,  L.) 
Bacteriosis  (Pseudomonas  pritni,  E.  F.  Sm.). 

N.  Y.  (Corn.)  Agr.  Exp.  Sta.,  Mem.  8  (1915). 
Black-knot  (Plowrightia  morbosa  (Schw.),  Sacc). 

Bull.  212,  Colo.  Exp.  Sta.  (October,  1915). 
Blight  (Bacillus  amylovorus  (Burr.),  Trev.) 

Colo.  Agr.  Exp.  Sta.,  Bull.  84  (1903). 
Blossom-rot  (Scleroiinia  lihcrliana,  Fckl.). 

Cal.  Agr.  Exp.  Sta.,  Bull.  218,  p.  1097  (191 1). 
Brown-rot  (Sckrotinia  fructigena  (Pers.),  Schrt.). 

Ibid. 
California  Blight  (Coryneum  Beijerinckit,  Oud.). 

Cal.  Agr.  E.xp.  Sta.,  Bull.  203,  p.  33  (1909). 
Die-back  (Valsa  leucostoma  (P.),  Fr.) 

Heald  &  Wolf,  Plant  Disease  Survey,  San  Antonio,  Tex.  (1912). 
Gummosis  (Various  causes). 

Amer.  Card.,  Vol.  XIX,  p.  606  (1898). 
Shot-hole  (Cylindrosporium  padi,  Karst). 

Heald  and  Wolf,  Plant  Disease  Survey,  San  Antonio,  Tex.  (191 2). 

Arbor-vit.e 
(Thuja  occidental  is,  L.) 
Die-back  (Peslalozzia  sp.) 

N.  J.  Agr.  E.xp.  Sta.,  Rep.,  p.  517  (1912). 
Root- rot  (Polyporus  Schiweinitzii,  Fr.). 

U.  S.  Dept.  Agr.  Div.  Veg.,  Phys.  &  Path.,  Bull.  25,  p.  23  (1900). 
27 


41 8  SPECIAL  PLANT  PATHOLOGY 

Ash 

{Fraxinus  sp.) 

Decay,  or  Brown-rot  {Polyporus  sulphureus  (Bull.),  Fr.). 
Heart-rot  {Fomes  fraxinophilus  (Pk,),  Sacc). 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  32  (1903). 

von  Schrenk,  H.,  Diseases  of  Deciduous  Forest  Trees,  U.  S.   Bur.  of    Plant 
Industry,  Bull.  149  (1909). 
Leaf-spot  {Cercospora  fraxinites,  Ell.  &  Ev.;  Cylindrosporium  viridis,  Ell.  &  Ev.,  and 

Septoria  submaculata,  Wint.). 
Rust  (yEcidium  fraxini,  Schw.). 

Rep.,  Conn.  Exp.  Sta.,  p.  304  (1903). 

Asparagus 
(Asparagus  offi-cinalis,  L.) 
Blight  {Cercospora  asparagi,  Sacc). 

Heald  &  Wolf,  Plant  Diseases  Survey  in  Texas  (191 2). 
Rust  {Puccinia  asparagi,  DC). 

N.  J.  Agr.  E.xp.  Sta.,  Bull.  129  (1898). 

Calif.  Bull.  165,  pp.  1-7,  18-9S,  98,  99,  figs.  32  (Jan.,  1905). 

Aster,  China 
{Callistephus  chinensis,  Nees) 

Rust  [Coleosporium  solidaginis  (Schw.),  Thiim). 
Wilt  {Fusarium  sp.). 

Mass.  (Hatch)  Agr.  Exp.  Sta.,  Bull.  79,  p.  5  (1902). 
Yellow  (undetermined). 

Ibid.,  p.  I  r. 

Azalea 

Rust  {Piicciniastrmn  minimum  (Schw.),  Arth.). 
Conn.  Exp.  Sta.,  Rep.,  p.  854  (1907-1908). 

Bamboo 

{Phyllostachys  henonis,  Mitf.  and  P.  quilioi,  Riv.) 

Smut  (Ustilago  Shiraiana,  Henn.). 

Patterson,  Flora  W.  and  Charles,  Vera  K.,  The  Occurrence  of  Bamboo  Smut 
in  America.     Phytopath.  6,  pp.  351-356  (1916). 

Banana 

(Musa  spp.) 

Trinidad  Bud-rot  {Bacillus  miisce,  Rorer.). 
Phytopath.  i,  pp.  43-49  (191 1). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  419 

Ripe  Fruit-rot  {Gleosporium  musorum,  Cke.  and  Mass.). 
Root  Disease  {Marasmius  semiustus,  Bri.  &  Cav.). 

See  Cook,  Diseases  of  Tropical  Plants,  1889,  pp.  133-136  (1913). 

Barley 

{Hordeum  sativum,  Jess.) 

Anthracnose  {CoUetotrkhum  cereale,  Manns)  =  graminicola  (Ces.)  Wilson  Phyto- 
path,  4:110. 

Ohio  Agr.  E.xp.  Sta.,  Bull.  203,  pp.  187-212  (1909). 
Covered-smut  {Ustilago  hordei  (Pers.),  K.  &  S.). 

Kan.  Agr.  Exp.  Sta.,  Rep.  2,  p.  269  (1890). 

Nebr.  Rep.,  pp.  45-53)  figs-  4  (iQoT)- 
Ergot  (Claviceps  purpurea  (Fr.),  Tul.). 

So.  Dak.  Agr.  Exp.  Sta.,  Bull.  33,  p.  38  (1893). 
Leaf-rust  {Puccmia  simplex  (Korn),  Erikss.  &  Henn.). 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  216  (1911). 
Loose-smut  {Ustilago  nuda  (Jens.),  K.  &  S.). 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  152,  p.  7  (1909). 
Powdery  Mildew  {Erysiphe  graminis,  DC). 

Bull.,  Ill  State  Lab.  Nat.  Hist,  Vol.  II,  pp.  387-432  (1887). 
Scab  (Gibberella  saubinetii  (Mont.),  Sacc). 

Ohio  Agr.  Exp.  Sta.,  Bull.  203,  pp.  212-232  (1909). 
Stem-rust  {Puccinia  graminis,  Pers.). 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull  216  (1911). 
Stripe  Disease  (Blade-blight)  {H dminthos poritim  gramineiim,  Rabenh.). 

Iowa  Agr.  E.xp.  Sta.,  Bull.  116,  p.  179  (1910). 

Bull.  218,  Calif.  Agr.  Exp.  Sta.  (June,  1911). 

Bean 

{Phaseolus  vulgaris,  L.) 

Anthracnose  {Colletotrichum  lindemuthianum  (Sacc.  &  Magn.),  Bri.  &  Cav.). 

N.  Y.  Agr.  Exp.  Sta.,  Bull.  48,  p.  310  (1892). 

Cornell  Bull.  255,  pp.  431-447,  figs.  6  (May,  1908). 

Mich.  Spec.  Bull.  68,  pp.  12  (March,  19 14). 
Bacterial-blight  {Bacterium  phaseoli,  E.  F.  Sm.). 

N.  Y.  Agr.  Exp.  Sta.,  Bull.  151,  p.  11  (1901). 

La.  Bull.  139,  pp.  43,  pis.  6  (January,  19 13). 
Leaf-spot  {Cercospora  canescens,  Ell.  &  Mart.). 

Heald  and  Wolf,  Plant  Disease  Survey  in  Texas.  (1912.) 
Damping-off  {Fungi  spp.). 
Pod-blight  {Phoma  subcircinata,  Ell.  &  Ev.). 

N,  J.  Exp.  Sta.,  Rep.,  p.  472  (1914). 
Rhizoctoniose  {Corticium  vagum,  Bri.  &  Cav.  var.  solani  Burt). 


420  SPECIAL   PLANT   PATHOLOGY 

Rhizoctonia  damping  off,  N.  Y.  (Cornell)  Agr.  Exp.  Sta.,  Bull.  94,  p.  266  (1895). 

Rhizoctonia  pod-spot,  Science,  new  ser.,  Vol.  XIX,  p.  268  (1904). 

Rhizoctonia  stem  rot.  Science,  new  ser.,  Vol.  XXXI,  p.  796  (1910). 
Rust  {Uromyces  appendiculatus  (Pers.),  Lev.). 

N.  Y.  Agr.  Exp.  Sta.,  Bull.  48,  p.  331  (1892). 
Southern  Blight  {Sderoiium  Roljsii,  Sacc). 

Fla.  Agr.  Exp.  Sta.,  Bull.  21,  p.  27  (1893). 

Bean  (Lima) 
(Phaseohis  liinalus,  L.j 

Bacterial  Blight  {Pseudomonas  phaseoU,  E.  F.  Sm.). 

N.  Y.  Agr.  Exp.  Sta.,  Bull.  48,  p.  331  (1892). 
Downy  Mildew  {Phylophthora  phascoli,  Thax.). 

Conn.  Agr.  Exp.  Sta.,  Rep.  167  (1889). 

Beech 

(Fagiis  gnindifolia,  Ehrh.) 

Sap-rot  {Polysticlus  pergameniis,  Fr.). 

von  Schrenk,  H.,  Disease  of  Desiduous  Trees,  U.  S.  Bureau  of  Plant  Industry, 
Bull.  149  (1909). 
White  Heart-rot  (Pomes  igniarlus  (L.),  Gill.). 

N.  Y.  (Cornell)  Agr.  Exp.  Sta.,  Bull.  193,  p.  214  (1901). 

Beet 

{Biia  vulgaris,  L.)   ■ 

Bacterial  Leaf-spot  {Bacterium  aptatum,  Brown  &  Jamieson). 

Journ.  Agr.  Research  i,  p.  190  (19 13). 
Cercospora  Leaf-spot  {Cercospora  belicola,  Sacc). 

N.  Y.  (Cornell)  Agr.  Exp.  Sta.,  Bull.  163,  p.  352  (1899). 

Nebr.  Bull.  73  (1902). 

Poole,  V.  W.  and  McKay,  M.  B.,  Relation  of  Stomatal  Movement  to  Infection 
by  Cercospora  beticola,  Journ.  Agr.  Research  5,  pp.  1011-1038  (1916). 
Crown-gall  (Pseudomonas  tumefaciens,  E.  F.  Sm.  &  Towns). 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  213  (1911). 
Curly-top  (undetermined). 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  122  (igcS). 

Smith,  Ralph  E,  and  Boncquet,  P,  A.:  Connection  of  a  Bacterial  Organism 
with  Curly  Leaf  of  the  Sugar  Beet  Phytopath.  5  pp.  335-342  (1915). 
Damping-off  (Fungi  spp.). 
Downy  Mildew  (Peronospora  Schachtii,  Fckl.). 

Bull.  218,  Calif.  Agr.  Exp.  Sta.  (June,  1911). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  42 1 

Leaf-scorch  (Non-par.). 

N.  Y.  Agr.  Exp.  Sta.  Bull.  162,  p.  167  (1899). 
Mosaic  (undetermined). 

Science,  new  ser.  Vol.  XLII,  p.  220  (1915). 
Phoma  Crown-rot  (Phoma  beta:  (Oud.)  Fr.). 

Frank  Die  Krankheiten  der  Pflanzen  Zweitl.  Aufl.  2,  p.  399  (1896). 

Journ.  Agr.  Research  4,  pp.  135-168,  pis.  11,  pp.  169-177  (1915). 
Phoma  Leaf-spot  (Phoma  beta;  (Oud.),  Fr.). 

Journ.  Agr.  Research  4,  p.  169  (1915). 
Phoma  Root-rot  (Phoma  beta;  (Oud.),  Fr.). 

Frank  Die  Krankheiten  der  Pflanzen  Zweite.  Aufl.  2,  p.  399. 
Puccinia  Rust  (Puccinia  siibnilens,  Diet.). 

Phytopathology  4,  p.  204  (1914). 
Rhizoctonia  Root-rot  (Cortkimn  vagiim,  Bri.  &  Cav.  var.  Solani  Burt). 

N.  Y.  (Corn.)  Agr.  Exp.  Sta.,  Bull.  163,  p.  34  (1899). 
Rust  (Uromyces  beta;.). 

Bull.  218,  Calif.  Agr.  Exp.  Sta.  (June,  1911). 
Scab  (Actinomyces  chromogenes). 

N.  Dak.  Agr.  Exp.  Sta.,  Bull.  4,  p.  15  (1891). 
Soft-rot  (Bac'erium  leutlium,  Mete). 

Nebr.  Agr.  Exp.  Sta.,  Rep.  17,  p.  69  (1904). 
Tuberculosis  (Bacterium  beticolmn,  E.  F.  Sm.). 

Ct.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  213,  p.  194  (1911). 
Uromyces  Rust  (Uromyces  beta;  (Pers.),  Lev.). 

U.  S.  Dept  Agr.  Rep.,  1887,  p.  350  (1888). 


Bermuda  Grass 

(Capriola  daclylon  (L.),  Kuntze) 

Leaf-spot  (Helminthos poriiim  giganleum,  Heald  &  Wolf). 
Heald  and  Wolf,  Plant  Disease  Survey  in  Texas  (191 2). 

Birch 

(Bclula  spp.) 

Decay  (Fomcs  fomenlarius  (L.),  Fr.). 
Red  Heart-rot  (Fomes  ftdvus,  Fr.). 

von   Schrenk,  H.,  Diseases  of  Deciduous  Forest  Trees,  U.  S.  Bureau  Plant 
Industry,  Bull.  149  (1909). 
Sapwood  Decay  (Polyporus  bclulini(s  (Bull.),  Fr.). 

von  Schrenk,  H.,  p.  57. 
White  Heart-rot  (Fomes  iguiariits  (L.),  Gill). 

N.  Y.  (Corn.)  Agr.  Exp.  Sta.,  Bull.  193,  p.  214  (1901). 


422  SPECIAL   PLANT   PATHOLOGY 

Blackberry 
{Riibus  spp.) 

Anthracnose  {Gleosporium  venetum,  Speg.)- 

U.  S.  Dept.  Agr.,  Rep.,  1887,  p.  357  (1888). 

Wash.  "Bull.  97,  pp.  3-18  (1910). 
Cane-blight  (Coniothyrium  Fuckelii,  Sacc). 
Crown-gall  {Bacterium  tumefaciens,  E.  F.  Sm.  &  Towns). 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  213  (1911). 
Double-blossom  (Fiisarium  ruhi,  Wint.). 

Del.  Agr.  Exp.  Sta.,  Bull.  93  (191 1). 
Gall  {Pycnochytrium  globosum,  Schrot). 
Late-rust  (Kuehneola  albida  (Kiihn),  Magn.). 

Mass.  (Hatch)  Agr.  Exp.  Sta.,  Rep.  9,  p.  74  (1897). 
Leaf-spot  (Septoria  ruhi,  Westd.). 

Conn.  Agr.  Exp.  Sta.,  Rep.  27,  p.  309  (1904). 
Orange-rust  {Gymnoconia  Peckiana  (Howe),  Tranz). 

111.  Agr.  Exp.  Sta.,  Bull.  29,  pp.  273-300  (1893). 

Box  Elder 

{Acer  negiindo  californicum  (T.  &  G.),  Sarg.). 

Leaf-spot  {Glwosporlumncgundinis,  Ell.  &  Ev.). 

Leaf-tip  Blight  {Septoria  marginata,  Heald  &  Wolf). 

Leaf-blight  Buckeye  {Aiscnlus  octandra,  Marsh).     {Phylloslicla  cesculi,  Ell.  &  Mart.) 

Boxwood 

{Buxus  sp.) 

Leaf-blight  {Macrophoma  Candollei  (B.  &  Br.),  Berl.  and  Vogl.). 
Leaf  and  Stem  Disease  {Volutella  buxi  (Cda.),  Berk.). 

Buckwheat 

{Fagopyrum  esculenlum,  Moench) 

Leaf-blight  {Ramularia  rufomaculans,  Pk.). 

Descr.,  Conn.  Agr.  Exp.  Sta.,  Rep.  14,  1890,  p.  98  (1891). 

Butternut 

{Juglans  cinerea,  L.) 

Leaf-spot  {Gnomonia  leptostyla  (Fr.),  Ces.  &  de  Not.). 

Mass.  (Hatch)  Agr.  Exp.  Sta.,  Rep.  10,  p.  69  (1898). 


LIST   OF    SPECIFIC   DISEASES    OF   PLANTS  423 

BUTTONBUSH 

{Ccphalanthiis  occidentaUs,  L.) 

Leaf-blight  {Cercospora  perniciosa,  Heald  and  Wolf). 
Leaf-spot  {Ramularia  cephalanthi  (Ell.  &  Kell.),  Heald). 

Cabbage 
{Brasska  oleracca,  L.) 

Bacterial  Leaf-spot  {Bacterium  maculicoliim,  McCul.). 

U.  S.  Dept.  Agr.  Bur.  Plant  Industry,  Bull.  225  (191 1). 
Black-leg  {Phoma  lingam  (Tode),  Desm.). 

Phytopathology  i,  p.  28  (1911). 
Black-mold  {Allcrnaria  hrassicce  (Berk.),  Sacc). 

U.  S.  Dept.  Agr.,  Farmers'  Bull.  488,  p.  31  (191 2). 

Black  leaf-spot,  Ibid. 

Black-mold  storage-rot,  Ibid. 
Black-rot  {Pseudonionas  campeslris  (Pam.),  E.  F.  Sm.). 

Wis.  Agr.  Exp.  Sta.,  Bull.  65  (1898). 
Black-spot  {Macros  port  urn  brassiccB,  Berk.).     {Allcrnaria  brassica,  (B.),  Sacc). 

Va.  Agr.  Exp.  Sta.,  Rep.  (1909-1910). 
Club-root  {Plasmodio phora  brassica,  Wor.). 

Journ.  Mycol.,  Vol.  VII,  p.  79  (1892). 

Va.  Bull.  191,  pp.  12,  figs.  5  (Apr.,  1911). 

Vt.  Bull.  175,  pp.  1-27,  pis.  4,  figs.  6  (Oct.,  1913)- 
Damping-off  {Fungi  spp.). 

U.  S.  Dept.  Agr.,  Farmer's  Bull.  488,  p.  31  (191 2). 
Downy  Mildew  {Peronos pora  parasitica  (Pers.),  deBy.). 

Ibid.,  p.  29. 
Drop  {Sclerotinia  libertiana,  Fckl.). 

Mo.  Bot.  Card.  Rep.  16,  p.  149  (1905). 
Leaf-spot  {Cercospora  Bloxami,  B.  &  Br.  (?)). 

Heald  and  Wolf,  Plant  Disease  Survey  in  Texas  (191 2). 
Root-rot  {Corticium  vagtini,  Bri.  &  Cav.,  var.  Sclani,  Burt.). 
Soft-rot  {Bacillus  carotovoruss,  Jone.) 

Journ.  Science,  new  ser..  Vol.  XVI,  p.  314  (1902). 
Yellows  {Fusarium  conglutinans ,  Wollenw.). 

Ohio  Agr.  Exp.  Sta.,  Bull.  228,  p.  263  (191 1). 

Cacao 

{Theobroma  cacao,  L.) 

Bark  Disease  {Corticium  javanicum,  Ziram.  =  C.  Zimmermanni,  Sacc.  &  Syd.) 
Diseases  of  Tropical  Plants,  pp.  180-191  (1913). 


424  SPECIAL   PLANT   PATHOLOGY 

Black-rot  {Phylophlhora  Faheri,  MaubL). 

Diseases  of  Tropical  Plants,  pp.  180-191  (1913). 
Exovin-rot  {Thyridaria  tarda,  HsLncxoit). 

Diseases  of  Tropical  Plants,  pp.  180-191  (1913). 
Canker  (Nectria  theohromcB,  Mass.,  and  Caloneclrla  jlavida,  Massee) 

Diseases  of  Tropical  Plants,  pp.  180-191  (1913). 
Pink  Disease  {Corticium  lilacofiiscum,  Berk,  and  Curt.). 

Diseases  of  Tropical  Plants,  pp.  180-191  (1913). 
Root  Disease  {Macrophoma  veslila,  Prill  &  Del.). 

Diseases  of  Tropical  Plants,  pp.  180-191  (1913). 
Scabby-pod  {Lasidoplodia  theohromce  (Pat.)  Griff.  &  Maubl). 

Diseases  of  Tropical  Plants,  pp.  180-191  (1913). 
Seedling  Disease  {Ramularia  nccator,  Mass.). 

Diseases  of  Tropical  Plants,  pp.  1 80-1 91  (1913). 
Thread-blight  (Marasmius  equicrinus,  Mull.). 

Diseases  of  Tropical  Plants,  pp.  180-191  (1913). 

Calla 

{Richard la  cthlopica,  Spreng.) 

Soft-rot  {Bacillus  aroidecd,  Towns.). 
Leaf-spot  {Phyllosticta  Richardia,  Hals.). 
Black-edge  {Cercospora  RichardlcBcola,  Atk.). 

Carnation 

{Dianthus  caryophyllus,  L.) 

Alternariose  {Alternaria  dianthi,  Stev.  &  Hall). 
A.nihxdiCno?,e  {Volulella  dlanthi,  Xikin'i), 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  pp.  385-386  (1894). 
Bud-rot  {Sporotrichum  anthrophilmn,  Pk.). 

Nebr.  Bull.  103,  pp.  3-24  (Jan.,  1908). 
Leaf-mold  or  Fairy-ring  {Helerosporium  cchinulatmn  (Berk.),  Cke.). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  p.  386  (1894). 
Die-back  {Fusarium  sp.). 

Descr.  Illus.,  N.  Y.  Agr.  Exp.  Sta.,  Bull.  164,  pp.  219-220  (1899). 
Leaf-spot  {Septoria  dianthi,  Desm.  and  Heterosporlum  cchinulatmn). 

Bull.  218,  Calif.  Agr.  E.xp.  Sta.  (June,  1911). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  pp.  384-385  (1894)- 
Rust  {Uromyces  caryophyllmus  (Schrank),  Wint.j. 

Descr.  Illus.,  Gar.  and  For.,  Vol.  V,  pp.  18-19  (1892). 

Treat.,  N.  Y.  Agr.  Exp.  Sta.,  Bull.  100,  pp.  50-68  (1896). 

Cf.  N.  Y.  Agr.  E.xp.  Sta.,  Bull.  175  (1900). 
Wilt  {Fusarium  sp.?). 

Descr.,  Conn.  Agr.  Exp.  Sta.,  Rep.  21,  1897,  pp.  175-181  (1898). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  425 

Carrot 

(Daucus  carota,  L.) 

Root-rot  {Corlicium  vagum,  Bfi.  &  Cav.,  var.  Solani,  Burt.)- 
Rot  {Phoma  sanguinolenla,  Grove). 
Soft-rot  {Bacillus  carotovoriis,  Jones). 

Duggar,  Fungous  Diseases  of  Plants,  p.  131  (1909). 

Catalpa 

{Catalpa  hignonloides,  Walt.) 

Leaf-blight  {Macros porium  catalpce,  Ell.  &  Mart.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  pp.  364-365  (r888). 

Treat,  (rec),  U.  S.  Dep.  Agr.,  Rep.  for  1887,  p.  366  (1888). 
Leaf-spot  {Phyllosticta  catalpce,  Ell.  &  Mart.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  pp.  364-365  (1888). 

Treat,  (rec),  U.  S.  Dep.  Agr.,  Rep.  for  1887,  p.  366  (1888). 
Soft  Heart-rot  {Polystictus  versicolor  (L.),  Fr.). 

Stevens,  Neil,  Mycologia  IV,  p.  263  (September,  1912). 

Cedar 
{Libocedriis;  Thuya;  Juniperus) 

Leaf-pit  {Keithia  thujina,  Durand). 

Phytopath  6,  pp.  360-363,  1916,  on  T.  plicata. 
Red-rot  or  "Pecky"  Disease  {Pomes  carneus,  Nees). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  21,  pp.  16-20  (1900). 
{Gymnosporangium  globosum,  Farl). 
{Gymnos porangiimt  junipcri-virginiance,  Sch w. ) . 
Rust     1  Nebr.  Rep.  i,  pp.  103-127,  pis.  13,  map  i  (1908). 

{Gymnos porangi urn  sabinm,  Plowr). 

Duggar,  Fungous  Diseases  of  Plants,  pp.  425-426. 
White-rot  {Polyporusjunipcrinus,  v.  Schr.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  21,  pp.  7-16 
(1900). 
\\'hitening  {Cyanospora  albiccdra:,  Heald  &  Wolf). 

Celery 
{Apium  graveolcns,  L.) 

Bacteriosis  {Bacterium  apii,  Brizi). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  12,  1891,  pp.  257-258  (1892). 
Cf.  U.  S.  Dep.  Agr.,  E.xp.  Sta.  Rec,  IX-9,  p.  850  (1898). 


426  SPECIAL   PLANT   PATHOLOGY 

Late-blight  (Septoria  pdroselini,  Desm,  var.  apii,  Br.  &  Cav.). 

Oregon  Sta.  Biennial  Rep.,  p.  273  (1911-12). 

Calif.  Bull.  208,  pp.  83-115,  pi.  I,  figs.  18  (Jan.,  1911). 
Leaf-blight  {Cercospora  apii,  Fres.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1886,  pp.  11 7-1 20  (1887). 

Treat,  (pos.).  Conn.  Agr.  Exp.  Sta.,  Rep.  21,  1897,  pp.  167-171  (1898). 
Leaf-spot  {Phyllosticia  apii,  Hals.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  12,  1891,  p.  253  (1892). 
Leaf-spot  {Septoria  petrosclini,  Desm.,  var.  apii,  Bi.  &  Cav.). 

Descr.  Illus.,  N.  Y.  Agr.  Exp.  Sta.,  Bull.  51,  pp.  137-138  (1893). 

N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  132,  pp.  206-215  (1897). 

Treat,  (rec),  N.  Y.  Agr.  Exp.  Sta.,  Bull.  51,  pp.  139-141  (1893). 
Rust  {Puccinia  bullata  (Pers.),  Wint.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  12,  1891,  p.  256  (1892). 

Century  Plant 

{Agave  amcricana,  L.) 

Blight  {Stagonospora  gigantea,  Heald  &  Wolf). 
Plant  Disease  Survey  in  Texas  (1912). 

Cherry 

{Priinus  cerasus,  L.) 

Black-knot  {Ploivrightia  morbosa  (Schw.),  Sacc). 

Descr.  Illus.,  Mass.  Agr.  Exp.  Sta.,  Rep.  8,  1890,  pp.  200-210  (1891). 
N.  J.  Agr.  Exp.  Sta..  Bui.  78.  pp.  2-10  (1891). 
N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  81,  pp.  638-646  (1894). 
Cf.  N.  Y.  Agr.  E.xp.  Sta.,  Rep.  12,  1893,  pp.  686-688  (1894). 
Treat,  (pos.),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  81,  pp.  646-653  (1894). 
Fruit-mold  {Sclerotinia  cinerea  (Bon.),  Schrot.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  349-352  (1889). 
Ky.  Agr.  Exp.  Sta.,  Rep.  2,  1889,  pp.  31-34  (1890). 
Mass.  Agr.  Exp.  Sta.,  Rep.  8,  1890,  p.  213  (1891). 
Treat  (pos.),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  98,  p.  409  (1895). 
Leaf-curl  {Exoascus  cerasi  (Fckl.),  Sadeb.). 

Descr.,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  14,  1895,  pp.  532-533  (1896). 
Leaf-spot  {Cylindrosporium  padi,  Karst.,  =  Septoria  cerasina,  Pk.). 
Descr.  Illus.,  Scribner,  Fung.  Dis.,  p.  119  (1890). 

Iowa  Agr.  Exp.  Sta.,  Bull.  13,  pp.  61-65  (1891). 
Treat,  (pos.),  Iowa  Agr.  Exp.  Sta.,  Bull.  30,  pp.  291-294  (1895). 
Leaf-spot  {Cercospora  cerasella,  (Aderh.);  Sacc). 
Powdery  Mildew  {PodosphcEra  oxycanth(B  (DC),  deBy.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  352-356  (1889). 
Treat,  (pos.),  Iowa  Agr.  Exp.  Sta.,  BulL  17,  pp.  421-433  (1892). 


Twig-blight 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  427 

Rust  {Puccinia  prtmi-spinoscB,  Pers.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  pp.  353-354  (1888). 
Scab  (Cladosporium  carpophilntn,  Thiim). 

{Sclerotinia  fructigena  (Pers.),  Schrot.). 

(Sderotinia  cinerea  (Bon.),  Schrot.). 

Chestnut 

{Castanea  dentata  (Marsh.),  Borkh.). 

[  (Cylindrosporium  castanicolum  (Desm.),  Berl.). 
Anthracnose     \  {Cryptosporiiim   epiphyllum,    C.  &  E.).     {  =  Marssonia  ochrolenca 
[      (B.  &  C),  Humph.). 

Treat,  (pos.),  Amer.  Gardening,  Vol.  XX,  p.  559  (1899). 
Blight  {Endothia  parasitica  (Murrill),  Anders.  Hall). 

Diseases  of  Economic  Plants,  p.  436  (igio). 

Conn.  Rep.,  pt.  5,  pp.  359-453,  pls-  8  (1912). 
Leaf-spot  (Marssonia  ochrolenca,  (Bri.  &  Cav.),  Humph.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  17,  1896,  p.  412  (1897). 

Descr.,  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1897,  p.  69  (1898). 
Sap-rot  {Polysticlus  versicolor  (L.)  Fr.). 

Chrysanthemum 
{Chrysanthemum-  sinense,  Sabine  &  C.  indicum,  L.) 

Leaf-blight  {Cylindrosporium  chrysanthemi,  Ell.  &  Dearn.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  pp.  365-368  (1895). 

Treat,  (rec),  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  p.  369  (1895). 
Ray-blight  {Ascochyta  chrysanthemi,  Stev.). 
Leaf-spot  {Phylloslicta  chrysanthemi,  Ell.  &  Dearn.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  p.  368  (1895). 
Leaf-spot  {Septoria  chrysanthemi,  Cav.).     {=S.  chrysanthemella  (Cav.),  Sacc.) 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  pp.  363-365  (1895). 

Treat,  (pos.),  N.  Y.  Agr.  Exp.  Sta.,  Rep.  11,  1892,  pp.  557-560  (1893). 
Ray-blight  {Ascochyta  chrysanthemi,  Stev.). 
Rust  {Puccinia  chrysanthemi,  Roze). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Circ,  Nov.  15  (1899). 

Descr.,  Treat,  (rec),  Ind.  Agr.  Exp.  Sta.,  Bull.  85  (1900). 
Cf.  Gardening,  Vol.  VI,  p.  277,  '98. 

Chives 

{Allium  schosnoprasum,  L.) 

Rust  {Puccinia  porri  (Sow.),  Wint.). 

Conn.  Exp.  Sta.,  Rep.,  1909-1910,  p.  726. 


428  SPECIAL  PLANT  PATHOLOGY 

Clematis 

(Clematis  spp.) 

Anthracnose  (GlcBosponumdcmatldis,  Sor.). 
Leaf-spot  (Ascochyta  clcmatidina,  Thiim). 

Journ.  Agr.  Research  4,  pp.  331-342  (igiS)- 
Root-rot  (Phoma  sp.) 

Descr.,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  3,  1884,  pp.  383-384  (1885). 

Clover 

{Trifolium   spp.) 

Anthracnose  (Collctolrichum  Irifolii,  Bain). 
Damping-off  (Pythiiim  de  Baryanum,  Hesse). 
Leaf-spot  (Pscudopcziza  IrifoHi  (Pers.),  Fckl.). 
Leaf-spot  {Phyllachora  trifoln  (P.),  Fckl.). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  18,  1897,  p.  319  (1898). 
Rust  (UromycesTrifolii  (Hedw.  f.),Lev.  and  U.  fallens  (Desm.),  Kern). 

Descr.  lUus.,  N.  Y.  (Corn.  Univ.)  x\gr.  Exp.  Sta.,  Bull.  24  (1890). 
Iowa  Agr.  Exp.  Sta.,  Bull.  13,  pp.  51-55  (1891). 
Phytopath.  i,  pp.  3-6  (February,  191 1). 

Treat,  (rec),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  24,  p.  139  (1890). 
Sooty  spot  {Polythrincium  Irifolii,  Kze.). 
Stem-rot  {Sclerotinia  trifoliorum,  Eriks.). 

Descr.  lUus.,  Del.  Agr.  Exp.  Sta.,  Rep.  3,  1890,  pp.  84-88  (1891). 

N.  J.  Agr.  Exp.  Sta.,  Rep.  18,  1897,  pp.  314-318  (189S). 

Treat,  (rec),  Del.  Agr.  Exp.  Sta.,  Rep.  6,  1893,  p.  no  (1894). 

COCKLEBUR 

{Xanthimn  spp.) 


Rust  {Piiccinia  xantkii,  Schw.). 


Coconut 
(Cocos  niicifcra) 


Bud-rot  {Bacillus  coli,  (Esch.)  Mig.). 

Johnston,  John  R.,  The  History  and  Cause  of  the  Coconut  Bud  Rot,  U.  S. 
Bureau  of  Plant  Industry,  Bull.  228  (191 2). 
Godaveri  Disease  {Pylkiiim  palmivorum,  Butler). 

Cook,  Diseases  of  Tropical  Plants,  pp.  197-206  (1913). 
Leaf  Disease  {Peslalozzia  palmarum,  Cooke.) 

Cook,  Diseases  of  Tropical  Plants,  pp.  197-206  (1913). 
Stem-bleeding  {Thiclaviopsis  ethacelicus,  Went.). 

Cook,  Diseases  of  Tropical  Plants,  pp.  197-206  (1913). 


LIST    OF   SPECIFIC   DISEASES    OF    PLANTS  429 

Coffee 
{Coffea  arabica.) 

Foot  Disease  {EiiryachoraUberica,  Oud.)- 

Cook,  Diseases  of  Tropical  Plants,  pp.  160-170  (1913). 

Porto  Rico  Bull.  17,  pp.  29  (Feb.,  1915). 
Leaf-rot  {Pellicularia  koleroga,  Cke). 

Cook,  Diseases  of  Tropical  Plants,  pp.  160-170  (1913). 

Porto  Rico  Bull.  17,  pp.  29  (Feb.,  1915)- 
Leaf -spot  {Cercospora  coffeicola,  Bri.  &  Cav.). 

Cook,  Diseases  of  Tropical  Plants,  pp.  160-170  (1913). 

Porto  Rico  Bull.  17,  pp.  29  (Feb.,  1915). 
Mancha  de  Hierro  {Sphccroslilbc  flavida,  Massee). 

Cook,  Diseases  of  Tropical  Plants,  pp.  160-170  (1913). 

Porto  Rico  Bull.  17,  pp.  29  (Feb.,  1915). 
Root  Disease  {Irpcx  flaviis,  Klotsch). 

Cook,  Diseases  of  Tropical  Plants,  pp.  160-170  (1913). 

Porto  Rico  Bull.  17,  pp.  29  (Feb.,  1915). 
Rust  {Hemileia  vastatrix,  Berk.  &  Broome). 

Cook,  Diseases  of  Tropical  Plants,  pp.  160-170  (1913). 

Porto  Rico  Bull.  17,  pp.  (Feb.  29,  1915). 
Stem  Disease  {Nccator  dccretus,  Mass.). 

Cook,  Diseases  of  Tropical  Plants,  pp.  160-170  (1913). 

Porto  Rico  Bull.  17,  pp.  29  (Feb.,  1915). 

Corn 

{Zca  mays,  L.) 

Downy  Mildew  {Scleras pora  macros pora,  Sacc). 
Leaf-blight  {Ilelminthosporiiim  inconspicuum,  C.  &  E.). 

Descr.  lUus.,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  15,  1896,  p.  452  (1897). 
Dry-rot  (Diplodia  zece  (Schvv.),  Lev.  =  D.  maydis  (Berk.  Sacc). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  335  (1910). 

111.  Bull.  133,  pp.  73-85,  92-100,  pi.  I,  figs.  20  (Feb.,  1909). 
Rust  {Puccinia  sorglii,  Schw.  =  P.  maydis  Bereng.) 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  p.  390  (1888). 

Cf.  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  16,  p.  65  (1899). 
Smut  {Ustilago  zecB  (Beckm.),  Unger)  and  (U.  Reiliana,  Kiihn). 

Descr.  Illus.,  Kans.  Agr.  Exp.  Sta.,  Bull.  62,  pp.  179-189  &  198-201  (1896) 
Ind.  Agr.  Exp.  Sta.,  Rep.  12,  pp.  99-112  (1900). 

Treat,  (rec),  111.  Agr.  Exp.  Sta.,  Bull.  57,  p.  335  (1900). 
Wilt  (Pseudomonas  Stewarti,  E.  F.  Sm.). 

Descr.  Illus.,  N.  Y.  Agr.  Exp.  Sta.,  Bull.  130,  pp.  423-438  (1897). 

Treat,  (rec),  N.  Y.  Agr.  Exp.  Sta.,  Bull.  130,  pp.  438-439  (1897) 


430  SPECIAL  PLANT   PATHOLOGY 

Cosmos 

(Cosmos  hipinnahis,  Cav.) 
Stem-spot  {Phlydana  sp.). 

Descr.  lUus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  pp.  371-372  (1895). 

Cotton 

{Gossypium  spp.) 

Angular  Leaf- spot  (Bacterium  malvacearum,  E.  F.  Sm.). 
Anthracnose  (Colletotrichum  gossypii,  South  worth); 

Descr.  Illus.,  Ala.  Agr.  Exp.  Sta.,  Bull.  41,  pp.  40-49  (1892). 

U.  S.  Dep.  Agr.,  Office  Exp.  Sta's,  Bull.  33,  pp.  293-299  (1896). 
Ala.  Bull.  153,  pp.  27-33  (Feb.,  191 1). 
Boll-rot  (Bacillus  gossypina,  Stedm.). 

Descr.  Illus.,  Ala.  Agr.  Exp.  Sta.,  Bull.  55  (1894). 

Treat,  (rec),  Ala.  Agr.  Exp.  Sta.,  Bull.  107,  p.  313  (1900). 
Damping-off  (Corlicium  vagum,  B.  &  C,  var.  Solani,  Burt.). 

Descr.,  Ala.  Agr.  Exp.  Sta.,  Bull.  41,  pp.  30-39  (1892). 

Cf.  Ala.  Agr.  Exp.  Sta.,  Bull.  107,  pp.  295-296  (1900). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  pp.  355-356  (1888). 
Ala.  Agr.  E.\p.  Sta.,  Bull.  41,  pp.  58-61  (1892). 
Leaf-mold  (Ramularia  areola,  Atk.). 

Descr.  Illus.,  Ala.  Agr.  Exp.  Sta.,  Bull.  41,  pp.  55-58  (1892). 
Root-rot  (Ozonium  omnivormn,  Shear). 

Descr.  Illus.,  Tex.  Agr.  Exp.  Sta.,  Rep.  2,  1889,  pp.  67-76  (1890). 

U.  S.  Dep.  Agr.,  Office  Exp.  Sta's,  Bull.  2,3,  P-  300  (1896). 

Treat,  (rec),  U.  S.  Dep.  Agr.,  Office  Exp.  Sta's,  Bull.  2,2,,  p.  304  (1896). 
Rust  (Uredo  gossypii,  Lagerh.)  and  (Mcidiiim  gossypii.  Ell.  &  Ev.). 

Descr.,  Journ.  Mycol.,  Vol.  VII,  pp.  47-48  (1891). 
Texas  Root-rot  (Ozonium  omnivorum,  Shear). 
Smut  (Doassansia  gossypii,  Lagerh.). 

Descr.,  Journ.  Mycol.,  Vol.  VII,  pp.  48-49  (1891). 
Wilt  (Neocosmospora  vasinfecta  (Atk.),  Smith). 

Descr.  Illus.,  Ala.  Agr.  E.xp.  Sta.,  Bull.  41,  pp.  19-29  (1892). 

U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  17  (1899). 

Cow  Pea 
(Vigna  catjang) 

Angular  Leaf-spot  (Cercospora  cruenta,  Sacc). 

Stevens  and  Hall,  Diseases  of  Economic  Plants,  p.  395  (1910). 
Leaf-spot  (Amerosporium  cecotunnicum,  Ell.  &  Tracy). 

Stevens  &  Hall,  p.  394  (1910). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  43 1 

Rust  (Uromyces  appendiculatus  (P.),  Lk.). 

Wilt  (Neocosmospora  vasinfecta  (Atk.),  E.  F.  Sm.)- 

Cranberry 
(Vaccinium  oxycoccus,  L.) 

Anthracnose  {Glomerella    rujomaculans  (Berk.)  Sp.  &  v.  Schr.  var.  vaccinii,  Shear). 
Gall  [Synchytrium  Vaccinii,  Thomas). 

Descr.  lUus.,  N.  J.  Agr.  Exp.  Sta.,  Bull.  64,  pp.  4-9  (1889). 

Treat,  (rec),  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  2,2>3  (1891). 
Hypertrophy  (Exobasidium  oxy cocci,  Rost  =  Ex.  vaccinii  (Fckl.)  Wor.). 
Rot  (Acanlhorhynchus  vaccinii.  Shear). 

Shear,  C.  L.,  Bull.  10,  U.  S.  Bur.  Plant  Industry. 
"Scald"  {Guignardia  vaccinii,  Shear). 

Descr.  lUus.,  N.  J.  Agr.  Exp.  Sta.,  Bull.  64,  pp.  30-34  (1889). 

Treat,  (rec),  N.  J.  Agr.  Exp.  Sta.,  Bull.  64,  pp.  39-40  (1889). 
Sclerotial  Disease  {Sclerotinia  oxycocci,  Wor.). 
Spot  {Pestalozzia  Guepini,  Desm.,  var.  vaccinii.  Shear). 

Cucumber 

{Cucitmis  sativus,  L.) 

Anthracnose  {Colletolrichum  lagenarium  (Pass.),  Ell.  &  Hals.). 

Descr.  lUus.,  Ohio  Agr.  Exp.  Sta.,  BuU.  89,  pp.  109-110  (1897). 

Treat,  (pos.),  N.  J.  Agr.  Exp.  Sta.,  Rep.  17,  1896,  pp.  340-343  (1897). 
W.  Va.  Bull.  94,  pp.  127-138,  pis.  5  (Dec.  2,  1904). 
Bacteriosis  or  Wilt  {Bacillus  tracheiphilns,  E.  F.  Sm.). 
"Damping-off"  or  Seedling-Mildew  {Pythium  de  Baryanum,  Hesse). 

Descr.  lUus.,  Mass.  Agr.  E.xp.  Sta.,  Rep.  8,  1890,  p.  220  (1891). 

Treat,  (rec),  Mass.  Agr.  Exp.  Sta.,  Rep.  8,  1890,  p.  221  (1891). 
Downy  Mildew  {Plasmopara  cubensis  (Bri.  &  Cav.),  Humphrey). 

Descr.  lUus.,  N.  Y.  Agr.  Exp.  Sta.,  Bull.  119,  pp.  158-165  (1897). 
Ohio  Agr.  Exp.  Sta.,  Bull.  89,  pp.  103-108  (1897). 

Cf.  Ohio  Agr.  Exp.  Sta.,  Bull.  105,  pp.  219-220  (1899). 

Treat,  (pos.),  Ohio  Agr.  Exp.  Sta.,  BuU.  105,  pp.  223-229  (1899). 
Leaf-glaze  {Acremonium  sp.). 

Descr.,  Mass.  Agr.  Exp.  Sta.,  Rep.  9,  1891,  p.  227  (1892). 

Illus.,  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  p.  230  (1893). 
Leaf-spot  {Phyllosticta  cuciirbitacearum,  Sacc). 

Occ,  Ohio  Agr.  Exp.  Sta.,  Bull.  105,  p.  222  (1899). 
Powdery  Mildew  {Erysiphe  polygoni,  DC). 

Descr.  Illus.,  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  p.  225  (1893). 

Treat,  (pos.),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  BuU.  31,  p.  138  (1891). 
Mass.  Agr.  Exp.  Sta.,  Rep.  9,  1891,  p.  225  (1892). 


432  SPECIAL   PLANT   PATHOLOGY 

Scab  {Cladosporium  cncunierinum,  Ell.  &  Arth.). 

Descr.  lUus.,  Ind.  Agr.  Exp.  Sta.,  Bull.  19,  pp.  8-10  (1889). 

Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  pp.  227-229  (1893). 
Stem-rot  {Sclerolinia  libertiana,  Fckl.). 

Descr.  lUus.,  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  pp.  212-224  (1893). 

Treat,  (rec),  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  p.  222  (1893). 

Currant 
{Rlbes,  spp.) 

Anthracnose  {Gloeosporium  rihis  (Lib.),  Mont.  &  Desm.). 

Descr.  lUus.,  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  15,  p.  196  (1889). 
Cane- wilt  {Dothiorella). 

Descr.,  N.  Y.  Agr.  Exp.  Sta.,  Bull.  167,  pp.  292-294  (1899). 
Cane-blight  {Neclria  cinnabarina  (Tode),  Fr.). 

Descr.  Illus.,  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  125  (1897). 

Treat,  (rec),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  125,  p.  38  (1897). 
Knot  {Pleonectria  beroUnensis,  Sacc). 

Cornell  Agr.  Exp.  Sta.,  Bull.  125  (February,  1897). 
Leaf-spot  {Septoria  rihis,  Desm.,  and  Cercospora  angulata,  Wint.). 

Descr.  Illus.,  Iowa  Agr.  Exp.  Sta.,  Bull.  13,  pp.  68-69  (1891). 

Treat,  (pos.),  Iowa  Agr.  Exp.  Sta.,  Bull.  30,  pp.  289-291  (1895). 
Powdery  Mildew  {Sphcerotheca  mors-itvce  (Schw.),  Bri.  &  Cav.). 
Rust  {Puccinia  Ribis,  DC). 

See  U.  S.  Dep.  Agr.,  Exp.  Sta.  Rec,  X-6,  p.  559  (1899). 
Wilt  {BotryosphcBria  ribis,  Gross.  &  Dug.). 

N.  Y.  Techn.  Bull.  18,  pp.  1 13-190,  pis.  2,  fig.  i  (July,  1911). 

{Cronartium  ribicola,  Diet.),  representing  the  uredo-  and  teleuto-stages  of  the 
white  pine  blister  rust,  Peridermium  slrobi,  Kleb,  a  serious  disease  of 
white  pines  against  which  a  strict  quarantine  is  maintained. 
N.  Y.  State  Techn.  Bull.  2,  pp.  61-74,  pls.  3  (1906). 

Cyclamen 

Dark  Leaf -spot  (Phoma  cydamena,  Halst.). 

Watery  Leaf-spot    (Glomerclla    rufomaculans    (Berk.),    Spauld.    &   v.    Schr.,    var. 
cyclaminis,  Patt.  &  Ch.). 

Cypress 
{Taxodium  distichiim  (L.),  Rich.) 

Leaf -blight  {Pestalozzia  funerea,  Desm.). 
"Pecky"  Disease  {Fungus  indet.). 


LIST   OF   SPECIFIC  DISEASES   OF   PLANTS  433 

Dandelion 

{Taraxacum  officinale,  Web.) 
Leaf-spot  {Ramtilaria  taraxaci  Karst.)- 


Conn.  Agr.  Exp.  Sta.,  Rep.,  p.  862  (1907-08). 


Egg-plant 

{Solanum  meJongena,  L.) 

Anthracnose  {Ghvosporiitm  melongcnce.  Ell.  &  Hals.). 

Occ,  N.  J.  Agr.  E.xp.  Sta.,  Rep.  12,  1891,  p.  281  (1892). 

Cf.  N.  J.  Agr.  Exp.  Sta.,  Rep.  13,  pp.  330-333  (1892). 
Blight  {Pseudomonas  solanacearum,  E.  F.  Sm.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  12  (1896). 

Treat,  (rec),  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  12,  pp.  23-24 
(1896). 
"Damping-off,"  or  "Seedling-mildew"  {Pylhium  de  Baryannm,  Hesse). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  13,  1892,  p.  286  (1893). 
Fruit-mold,  Gray  Mold  {Botrylis  fascicularis  (Cord.),  Sacc). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  357  (1891). 
Leaf-spot  Phomopsis  vexans  (Sacc.  &  Wint.),  Hart.   =  Ascochyla  hortorum  (Speg.), 

C.  O.  Smith,  a  fruit  rot). 

Journ.  Agr.  Research  H,  pp.  331-338,  pis.  5  (1914). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  189c,  pp.  355-357  (1891). 

Del.  Bull.  70,  pp.  10-15,  pi.  I,  figs.  2  (March,  1905). 

Treat,  (pos.),  N.  J.  Agr.  Exp.  Sta.,  Rep.  17,  1896,  pp.  337-340  (1897). 
Rot  {Penicilliiim  sp.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  pp.  362-366  (1894). 
Seedling-rot  {Phomopsis  vexans,  Sacc.  &  Syd.,  Hart.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  12,  1891,  pp.  277-279  (1892). 

Treat,  (rec),  N.  J.  Agr.  Exp.  Sta.,  Rep.  12,  1891,  p.  279  (1892). 
Stem-rot  {Neciria  ipomcecE,  Hals.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  12,  1891,  pp.  281-283  (1892), 

Elder 
{SambucHS  canadensis,  L.) 
Rust  {Aecidiiim  samhiici,  Sacc). 
Leaf- spot  {Ccrcospora  catenas pora,  Atk.). 

Elm 

(Ulmus  spp.) 

Black-spot  {Dolhidella  idmi  (Duv.),  Wint.)  and  {Gnomonia  uhnea  (Sacc),  Thiim  ) 
Blister-canker  {Nmnmularia  discreta,  (Schw.)  TuL). 
Duggar,  p.  282  (1909). 
28 


434  '  SPECIAL  PLANT   PATHOLOGY 

Leaf-scab  (Gnomonia  nlmea  (Sacc),  Thiim.). 
White-rot  {Polyporus  squamosus  (Huds.),  Fr.)- 
Duggar,  p.  453  (1909). 

English  Ivy 
{Hedera  helix,  L.) 

Anthracnose  {CoUetolrichum  glceosporioides,  Penz,  var.  hedera,  Pass. 
Leaf-blight  {Phyllosticla  concentrica,  Sacc). 
Leaf-spot  {Ramidaria  hedericola,  Heald  &  Wolf). 


Evening  Primrose 
{Oenothera  biennis,  L.). 

Gall,  or  Chytridiose  {Synchytriiim  fulgens,  Schrot.). 
Duggar,  p.  139  (1909). 

.  Fig 
{Ficiis  carica,  L.) 

Anthracnose  {Glomerella  riifomaculans  (Berk.)  Spauld  &  von  Schr.  =  G.  Jrucligena 

(Clint.),  Sacc.) 
Canker  {Tubercularia  fici,  Edgerton). 

Cook,  Diseases  of  Tropical  Plants,  p.  139  (19 13). 

Phytopath.  i,  pp.  12-17  (February,  191 1). 
Die-back  {Diplodia  sycina,  Mont.,  var.  syconophila,  Sacc). 
Fruit-rot  {Glomerella  riifomaculans  (Berk.  Spauld.  &  von  Schr.). 
Leaf-blight  {Cercospora  Bolleana  (Thiim.),  Sacc). 

Occ,  U.  S.  Dep.  Agr.,  Div.  Pomol.,  Bull.  5,  pp.  27-28  (1897) 
Leaf-spot  {Cercospora  fici,  H.  &  W.). 
Limb-blight  {Corticium  latum,  Karst.). 
Rust  {Uredofici,  Cast.  =  Physopella  fici  (Cast.),  Arth.). 

Occ,  N.  C.  Agr.  Exp.  Sta.,  Bull.  92,  p.  117  (1893). 
Scab  {Fusarium  roseum,  Lk.) . 

Occ,  N.  C.  Agr.  Exp.  Sta.,  Bull.  92,  p.  117  (1893). 
Soft-rot  {Rhizopus  nigricans  Ehrenb.). 

La.  Agr.  Exp.  Sta.,  Bull.  126  (March,  1911). 


Filbert 

{Corylus  avellana,  L.  and  C  amerlcana,  Walt.) 

Black-knot  {Cryptosporella  anomala  (Pk.),  Sacc). 

Descr.,  N.  J.  Agr.Exp.  Sta.,  Rep.  13,  1892,  pp.  287-289  (1893). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  435 

Fir 

{Abies  balsamea  (L.),  Miller) 


Dry-rot  {Trametes  pini  (Brot.),  Fr.) 
Root-rot  {Polyporus  Schweinitzii,  Fr.) 
Wet-rot  {Polyporus  subacidus,  Pk.?) 
Rust  {Aecidium  elatinum,  Alb.  &  Schw.) 


Descr.  Illus.,  U.  S.  Dept.  Agr.,  Div.  Veg. 
Phys.  &  Path.,  Bull.  25  (1900). 


Flax 

{Liniim  spp.) 

Rust  {Melampsora  lini  (DC),  Tul.). 

Occ,  Journ.  Mycol.,  Vol.  V,  p.  215  (1889). 
Wilt  {Fusariiim  lini,  BoUey). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  406  (1910). 

N.  Dak.  Bull.  50,  December,  1901,  pp.  27-60,  figs.  18. 

Geranium 

{Pelargonium  spp.) 
Leaf-spot  {Bacteria'^). 

Descr.,  Mass.  Agr.  Exp.  Sta.,  Rep.  le,  1899,  p.  57  (1900). 
Kot  {Bacillus  i^.). 

Descr.  Illus.,  Journ.  Mycol.,  Vol.  VI,  pp.  114-115  (1891). 

Ginseng 

{Panax  quinquefolium,  L.).^ 

Anthracnose  {Vermicular ia  dematium  (Pers.),  Fr.). 
Blight  {Alternaria  panax,  Whetz). 
Leaf  Anthracnose  {Pestolozzia  funerea,  Desm.). 

Wilt  {Neocosmopara  lasinfectum  (Atk.)  E.   F.   Sm.   var  nivea  (Atk.)  E.  F.  Sm.). 
Mo.  Bull.  69  (October,  1905). 

Gladiolus 

Hard-rot  {Septoria  gladioli,  Passer). 

Phytopathology  6  (Columbus  Meeting  Abstracts). 

GOLDENROD 

{Solidago  spp.) 

Red-rust  {Coleosporium  solidaginis  (Schw.),  Thum). 
Rust  Uromyces  solidaginis  (Somm.),  Niessl. 

1  See  Whetzel,  H.  H.:  The  Diseases  of  Ginseng  and  Their  Control,  U.  S.  Bur. 
of  Plant  Industry,  Bull.  250  (191 2). 


436  SPECIAL   PLANT   PATHOLOGY 

Gooseberry 

{Ribes  grossularia,  L.) 

Leaf-spot  {Septoria  ribis,  Desm.,  and  Cercospora  angulata,  Wint.)- 
Leaf-spot  {Sphmrella  grossularia  (Fr.),  Awd.?). 

Occ.  Illus.,  Iowa  x\gr.  Exp.  Sta.,  Bull.  13,  p.  70  (1891). 
Powdery  Mildew  {Spkarotheca  mors-uvcR  (Schw.),  Bri.  &  Cav.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  pp.  373-378  (1888). 
Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  p.  240  (1893). 

Treat,  (pos.),  N.  Y.  Agr.  Exp.  Sta.,  Bull.  161  (1899). 
Root-rot  {Dcmatophora  sp.?). 

Descr.,  N.  Y.  Agr.  Exp.  Sta.,  Bull.  167,  pp.  295-296  (1899). 
Rust  {Aecidium  grossularicB,  Schum.). 

Descr.,  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  p.  241  (1893). 

Treat,  (rec),  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  p.  241  (1893). 

Grape 

{Vilis  spp.) 

Anthracnose  {S phaceloma  ampdinitm,  deBy.  =  GJocosporium  ampdophagmn  (Pass.) 
Sacc). 
Descr.  Illus.,  Tenn.  Agr.  Exp.  Sta.,  Bull.  IV-4,  pp.  111-112  (1891). 
Descr.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Path.,  Bull.  2,  pp.  170-172  (1892). 
Shear,  C.  L.   Grape    Anthracnose  in  America.  Rep.  Int.  Congr.  Viticulture, 

San  Francisco,  July  11-13,  191 5:  111-117. 
Treat,  (rec),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  76,  p.  443  (1894). 
Hawkins,  LonA.  Circ.  105,  Bureau  PI.  Industry,  1913. 
Bacteriosis  {Bacillus  sp.). 

See  U.  S.  Dep.  Agr.,  Exp.  Sta.  Rec,  VI-3,  pp.  231-232. 
Bitter-rot  {Melanconium  fuligincmn  (Scrib.  &  Viala.),  Cav.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  pp.  324-325  (1888). 

Scribner,  Fung.  Dis.,  pp.  37-40  (1890). 
Cf.  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  61,  pp.  302-305. 
Black-rot  {Guignardia  {Lacsiadia)  BidweUii  (Ell.),  Viola.  &  Rav.  and  G.  ba'cca  (Cav.), 
Jacq.). 
Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1886,  pp.  109-111  (1887). 
Del.  Agr.  Exp.  Sta.,  Bull.  6,  pp.  18-27  (1889). 
Tenn.  Agr.  Exp.  Sta.,  Bull.  IV-4,  pp.  97-102  (1891). 
Tex.  Agr.  Exp.  Sta.,  Bull.  23,  pp.  219-228  (1892). 
Penna.  Bull.  66,  pp.  1-16,  pis.  2,  map.  i  (Jan.,  1904). 
N.  Y.  Cornell  Bull.  293,  pp.  289-364,  pis.  5  (March,  191 1). 
Treat,  (pos.),  Conn.  Agr.  Exp.  Sta.,  Rep.  14,  1890,  pp.  loo-ioi  (1891). 
U.  S.  Dep.  Agr.,  Farm.  Bull.  4,  pp.  8-9  (1891). 
Tex.  Agr.  Exp.  Sta.,  Bull.  23,  pp.  228-231  (1892). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  437 

Chytridiose  {Cladochylrium  vilicolum,  Prunet.). 

See  U.  S.  Dep.  Agr.,  Exp.  Sta.  Rec,  VI-7,  pp.  642-644  (1895). 
Dead-arm  {Cryplosporella  viticola,  Shear.). 
Circ.  55,  N.  J.  Agr.  Exp.  Sta. 
N.  Y.  State  Bull.  389,  pp.  463-490  (Julj',  1914). 
Phytopath.  i,  pp.  116-119  (1911). 
Uowny  Mildew  (Plasmopara  viticola  (B.  &  C),  Berl.  &  De  Ton.). 
Descr.  IIlus.,  U.  S.  Dep.  Agr.,  Rep.  for  1886,  pp.  96-99  (1887). 
Tenn.  Agr.  E.\p.  Sta.,  Bull.  IV-4,  p.  108  (1891). 
Mich.  Agr.  E.xp.  Sta.,  Bull  83,  pp.  9-12  (1892). 
Phytopath.  2,  pp.  235-249  (1912). 
Treat,  (pos.),  U.  S.  Dep.  Agr.,  Farm.  Bull.  4,  p.  8  (1891). 
Fruit- mold  (Bolrytis  sp.). 
Leaf-blight  Isariopsis  claviipora  (B.  &  C.)  Socc. 

Descr.  Illus.,  Scribner,  Fung.  Dis.,  pp.  60-62  (1890). 

N.  Y.  Agr.  Exp.  Sta.,  Rep.  9,  1890,  p.  324  (1891). 
Cornell  Bull.  76,  November,  1894. 
Treat,  (rec),  N.  C.  Agr.  Exp.  Sta.,  Bull.  92,  p.  122  (1893). 
Leaf-mold  {Leptosporium  hderosporum,  Ell.  &  Gall.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  381-383  (1889). 
Leaf-spot  {Isariopsis  davispora,  Sacc). 

N.  J.  Exp.  Sta.,  Rep.,  p.  474  (1914). 
Powdery  Mildew  {Uncimda  necator  (Schw.),  Burr.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1886,  pp.  105-108  (1887). 

N.  Y.  Agr.  Exp.  Sta.,  Rep.  9,  1890,  pp.  322-323  (1891). 
U.  S.  Dep.  Agr.,  Div.  Veg.  Path.,  Bull.  2,  pp.  166-170  (1892). 
Treat,  (pos.),  U.  S.  Dep.  Agr.,  Farm.  BulL  4,  p.  8  (1891). 

N.  C.  Agr.  E.xp.  Sta.,  Bull.  92,  pp.  120-121  (1893). 
Ripe- rot  or  Anthracnose  {Glceosporium  fructigemim,  Berk.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1890.  p.  408  (1891). 
Journ.  Mycol.,  Vol.  VI,  pp.  164-171  (1891). 
Root- rot  {Demalophora  necatrix,  Hartig). 

Descr.  Illus.,  Scribner,  Fung.  Dis.,  pp.  64-69  (1890). 

U.  S.  Dep.  Agr.,  Div.  Veg.  Path.,  Bull.  2,  pp.  153-159  (1892), 
Treat.  N.  C.  Agr.  Exp.  Sta.,  Bull.  92,  p.  122  (1893). 
Root-rot  {Annillaria  mcllca,  Vahl.). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  173  (1910). 
Scab  (Cladosporium  vilicolum,  Ces.  =  Cercospora  viticola  (Ces.)  Sacc.) 

Descr.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Path.,  Bull.  2,  pp.  173-174  (1892). 
Scald  {Aureobasidium  litis,  Viala  &  Boyer). 

See  U.  S.  Dep.  Agr.,  E.xp.  Sta.  Rec,  VI-3,  pp.  230-231  (1894). 
Twig-blight  {Bolrytis  cinerea,  Pers.). 

White-rot    {Charrinia   diphdiella,  Viala   &    Rav.;    Syn.    Coniolhyriiim  diplodidla 
(Speg.)  Sacc). 
Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  pp.  325-326  (1888). 

Scribner,  Fung.  Dis.,  pp.  41-44  (1890). 
Treat,  (pos.),  U.  S.  Dep.  Agr.,  Sec.  Veg.  Path.,  Bull.  11,  p.  69  (1890). 


438  SPECIAL   PLANT   PATHOLOGY 

GUAVA 

{Psidium  guajava,  L.) 

Ripe-rot  {Glonierclla  psidii  (G.  Del.)  Sheldon). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  191  (1910). 
W.  Va.  Bull.  104,  pp.  299-315  (April,  1906). 

Hackberry 

{Cellis  spp.) 

Leaf-spot   {Cylindros poriuni  defoliaium,  Heald  and  Wolf   and  {Ramularia  ccUidis, 

EU.  &  Kell.). 
Powdery  Mildew  {Uncinula  polychccta,  Bri.  and  Cav.). 

Hazel 

{Corylus  spp.) 

Black-knot  {Cryplosporella  anomala  (Pk.),  Sacc). 

Descr.  lUus.,  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  p.  242  (1893). 
Treat,  (rec),  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  p.  243  (1893). 

Hemlock 
{Tsuga  canadensis  (L.),  Carr.) 

Dry-rot  {Trametcs  pini  (Brot.),  Fr.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  25  (1900). 
Heart-rot  {Polyporus  borealis  (Wahl.),  Fr.). 

Bull.  193  Corn.  Univ.  Agr.  Exp.  Sta.  (June,  1901). 
Timber  Rot  {Fames  pinicola,  Fr.) . 

Graves,  A.  H.,  Phytopath.  4,  p.  69  (April,  1914). 
Wet-rot  {Polyporus  siihacidus,  Pk.  ?) . 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  25  (1900). 
Rust  {Peridermium  Peckii,  Thiim.) . 

Phytopath.  i,  pp.  94-96  (191 1). 

Hemp 

{Cannabis  saliva,  L.) 

Leaf- wilt  {Bolryosphceria  Marconii  (Cav.),  Charles  &  Jenkins). 
Journ.  of  Agr.  Research  3,  pp.  81-84  (Oct.  15,  1914). 

Hickory 

{Carya  spp.) 
Leaf-spot  {Marsonia  juglandis  (Lib.),  Sacc). 


LIST   OF    SPECIFIC   DISEASES    OF   PLANTS  439 

Hollyhock 
{AlthcEa  rosea,  Cav.) 

Anthracnose  {Colletolrichum  malvarum  (Braun.  &  Casp.),  Southworth). 

Descr.  Illus.,  Journ.  Mycol.,  Vol.  VI,  pp.  46-48  (1890). 

Treat,  (pos.),  Journ.  Mycol.,  Vol.  VI,  p.  50  (1890). 

N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  362  (1891). 
Leaf-blight  [Cercospora  althaina,  Sacc). 

Descr.,  N.  j.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  361  (1891). 

Treat,  (pos.),  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  361  (1891). 
Leaf-Spot  {Phyllosticta  althmina,  Sacc.).^ 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  12,  1891,  p.  297  (1892). 
Rust  {Puccinia  malvacearum,  Mont.). 

Descr.  Illus.,  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  25,  p.  154  (1890). 
Phytopath.  i,  pp.  53-62  (191 1). 

Treat,  (rec),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  25,  p.  155  (1890). 
Rust  {Puccinia  helerogenea,  Lagerh.) 

Descr.  Illus.,  Journ.  Mycol.,  Vol.  VII,  pp.  44-47  (1891). 

Hop 

{Humuliis  japonicus,  Sieb  &  Zucc.) 

Powdery  Mildew  {Spharotheca  hiimtdi  (DC),  Burr.). 

N.  Y.  Corn.  Bull.  328,  pp.  281-310,  figs.  19  (March,  1913). 

N.  Y.  State  Bull.  395,  pp.  29-80,  pis.  2,  figs.  2  (February,  1915). 

Horse-chestnut 

{jEschIus  hippocastaniim,  L.) 

Leaf-blotch  {Gitignardia  csscidi  (Pk.)  Stewart).     Phytopath.  6,  5-19,  1916. 
Leaf-spot  {Phyllosticta  pavice,  Desm.). 

Descr.,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  15,  1896,  p.  456  (1897). 
Tr.  (pos.),  Journ.  Mycol.  Vol.  VII,  p.  353;   Phytopathology  4,  399  (December, 
1914) 

Horseradish 

{Cochlearia  armoracia,  L.) 

Leaf-blight  {Ramularia  armoracia,  Fckl.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  360  (1891). 
Leaf- mold  {M acres porium  herculeum.  Ell.  &  Mart.). 

Occ,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  15,  1896,  p.  452  (1897). 
'  The  dififerent  species  of  Phyllosticta  will  be  found  described  in  The  North  Ameri- 
can Phyllostictas  with  Descriptions  of  the  Species,  published  up  to  August,  1900  by 
J.  B.  Ellis  and  B.  M.  Everhart,  Vineland,  N.  J.,  December,  1900. 


440  SPECIAL   PLANT   PATHOLOGY 

Leaf-spot  {Scploria  armoracice,  Sacc.)- 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  ii,  1890,  p.  360  (1891). 

Huckleberry 
(Gaylussacia  sp.) 
Gall  {Exohasidiitm  vaccinii  (Fckl.)  Wor.j. 

Hyacinth 
{Hyacintlius  oricnlalis,  L.) 
Yellow  Disease  {Pscudomonas  hyacinihi  (Wakk.)  E.  F.  Sm.). 

Hydrangea 

{Hydrangea  horlensia,  Siebold) 

Leaf-spot  {Pliyllostkta  hydrangea,  Ell.  &  Ev.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  12,  1891,  p.  298  (1892). 
Rust  {Melampsora  Hydrangea  =  Thecopsora  hydrangea  B.  &  C.)  Magn. 

Incense  Cedar 
{Libocedrus  decurrens,  Torr.) 

Dry-rot  {Poly poms  amarus,  Hedgcock). 

Rust  {Gymnosporanglum  Blasdaleanum  (Diet.  &  Holw.)  Kern). 

Meinecke,  E.  A.,  Forest  Tree  Diseases  Common  in  California  and  Nevada,  1914. 

Iris 

{Iris  spp.) 

Bulb-spot  {Mystrosporium  adustum,  Mass.). 
Leaf-blight  {Botrytis  galanthina,  (B.  &  Br.)  Sacc). 

Johnson  Grass 
{Andropogon  halepensis  (L.),  Brot.). 

Leaf-blight  {Helminthosporiuni  turcicum  Pass,  and  Septoria  pcrlitsa  Heald  &  Wolf). 
Leaf-spot  {Cercospora  sorghi  (Ell.  &  Ev.)  and  Colletolrichiim  lineola  Cda  var.  hale- 

pense,  Heald  &  Wolf). 
Rust  {Puccinia  purpurea,  Cke.). 

Kaffir  Corn 

{Sorghum  vulgare,  Pers.) 

Grain  Smut  {Sphacetolheca  sorghi  Lk.)  Clint. 
Clint  Conn.,  Exp.  Sta.  Rep.,  p.  351  (1912). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  441 

Larch 

(Larix  lan'cina  (DR.)  Koch) 

Canker  (Dasyscypha  Willkommii,  Hartig). 
Dry-rot  (Tramdes  pint  (Brot.)  Fr.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  25,  pp.  31-40 
(1900). 

Laurel 

{Kalmla  laiijolia,  L.) 

Leaf-spot  {Seploria  kalniicola  (Schw.)  Bri.  &  Cav.). 

Lemon 
{Citrus  mcdica,  L.  var.  Union,  L.) 

Black  pit  {Bacillus  citripuleale  spp.) 

Coit,  Citrus  Fruits,  p.  401,  1915;  Phytopath.  3,  pp.  277-281  (1913). 
Brown-rot  {Pythiacystis  dtrophthora,  R.  E.  Smith). 

Calif.  Bull.  190,  pp.  1-72,  pi.  I,    figs.  30  (July,  1907). 
Foot-rot  {Fusisporium  limonis,  Bri.). 
Cotton-rot  {Sclerotinia  libertiana,  Fuckl.j.     Phytopath.  6,  pp.  268-278  (1916). 

Fruit-spot  {Trichoseploria  alpci,  Cav.). 
Leaf-spot  {Ccrcospora  aurantia.^  Heald  &  Wolf). 
Melanose  {Fungus  indel?). 

Canker  {Pscudomonas  citri,  Hassej.     Journ.  Agr.,  Res.  4:  97-150  (1915). 
Scab  {Cladosporium,  sp.). 

Descr.  Illus.,  U.  S.  Dept.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  8,  pp.  20-23 
(1896). 

Treat,  (pos.),  U.  S.  Dept.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  8,  pp.  23-24 
(1896). 
Sooty- mold  {Mcliola  Penzigi,  Sacc.  and  M.  Camdlice  (Catt.),  Sacc.j. 
Twig- blight  {Diplodia  aurantii,  Catt  and  Sphceropsis  maloruin,  Berk.). 
White-rot  {Sclerotinia  libertiana  Fckl.)  Bull.  218,  Calif.  Agr.  Exp.  Sta.  (June,  191 1). 
Wither-tip  {Colletotrichum  glceosporioidcs  Penz. 

Plant  Disease,  Survey  San  Antonio  Texas  (191 2). 

Lettuce 
{Lactuca  sativa,  L.) 

Anthracnose  {Marssonia  perforans,  Ell  &  Ev-.). 

Descr.  Illus.,  Ohio  Agr.  Exp.  Sta.,  Bull.  73,  pp.  222-223  (1897). 
Treat,  (rec),  Ohio  Agr.  Exp.  Sta.,  Bull.  73,  pp.  225-226  (1897J. 


442  SPECIAL   PLANT   PATHOLOGY 

Downy  Mildew  (Breniia  lacluca,  Regel). 

Descr.  Illus.,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  4,  1885,  p.  253  (1886). 

Treat,  (pos.),  Ohio  Agr.  Exp.  Sta.,  Bull.  73,  p.  226  (1897). 
Drop  {Schrotinia  libertiana,  Fckl.). 

Descr.  Illus.,  Mass.  Agr.  Exp.  Sta.,  Bull.  69,  pp.  12-15  (1900). 

N.  C.  Bull.  217,  1-21,  figs.  8  (July,  1911). 

Treat,  (pos.),  Mass.  Agr.  Exp.  Sta.,  Bull.  69,  pp.  17-35  (19°°) 
Leaf-mold,  Gray  Mold  or  Rot  {Botrytis  cinerea,  Pers.;. 

Descr.  Illus.,  Mass.  Agr.  Exp.  Sta.,  Bull.  69,  pp.  7-12  (1900). 
Leaf-rot  {Rhizoclonia  sp.). 

Descr.  Illus.,  Mass.  Agr.  Exp.  Sta.,  Bull.  69,  pp.  16-17  (1900) 

Treat,  (pos.j,  Mass.  Agr.  Exp.  Sta.,  Bull.  69,  pp.  39-40  (1900). 
Leaf-spot  {Septoria  conslmilis,  Ell.  &  Mart.). 

Descr.  Illus.,  Ohio  Agr.  Exp.  Sta.,  Bull.  44,  pp.  145-146  (1892) 
Stem-rot  (Bacterial). 

Descr.,  Vt.  Agr.  Exp.  Sta.,  Rep.  6,  1892,  p.  87  (1893). 

Treat,  (rec.)  Vt.  Agr.  Exp.  Sta.,  Rep.  6,  1892,  p.  88  (1893). 

Lilac 

{Syringa  vulgaris,  L.) 

Leaf-spot  {Phyllosticta  Halstedii,  Ell.  &  Ev.). 
Powdery  Mildew  {Microsphcera  aim  (Wallr.)  Wint.). 
Leaf-blight  {Cercospora  macromaculans.  Heald  &  Wolf). 

Lily 
(Liliiim  spp.) 
Bermuda  Disease. 

See  U.  S.  Dept.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  14  (1897) 
Bulb-rot  {Rhizopus  necans,  Massee). 
Mold  or  Ward's  Disease  {Sclerotinia  Fuckcliana  deBy.). 
Treat,  (pos.).  Gar.  and  For.,  IX-414,  p.  44  (1896). 
See  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  pp.  392-394  (1894) 

Linden 
{Tilia  spp.) 

Leaf-blight  {Cercospora  microsora,  Sacc). 

Occ,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  15,  1896,  p.  454  (1897). 
Stem-rot  {Botrytis  cinerea,  Pers.). 

Locust 
{Rohinia  pseiidacacia,  L.) 

Leaf-spot  {Cylindrosporium  solitarinm,  Heald  &  Wolf). 
Heart-rot  {Trametes  robiniophila,  Murr.  and  Fames  rimosus  Berk.) . 
Diseases  of  Deciduous  Trees  (1909). 


LIST    OF   SPECIFIC   DISEASES    OF   PLANTS  44^3, 

LOQUAT 

(Eriobotrya  japonica,  Lindl.) 
Scab  {Fitsicladium  dendrUicum  (Wallr.),  Fckl.  var.  EriobolrycB,  Scalia. 

Lupine 
{Lupinus,  spp.) 
Blight  (Fcstalozzia  litpini,  Sor.). 

Magnolia 
{Magnolia  grandijlora,  L.) 
Leaf-spot  {PhyUoslicla  magnolia  Sacc.  Duggar,  p.  347  (1909). 

Mango 

(Mangifcra  indica,  L.) 

Anthracnose  (Collelelolrichnm  glceosponoides,  Penz.). 
McMurran  Bull.  U.  S.  Dept.  Agr.  No.  52  (1914). 

Maple 
(Acer  spp.) 

Anthracnose  {Glaosporium  apocrypium,  Ell.  &  Ev.). 

Descr.,  N.  Y.  Agr. .Exp.  Sta.,  Rep.  14,  1895,  pp.  531-532.  (1896). 

Treat,  (rec),  N.  Y.  Agr.  Exp.  Sta.,  Rep.  14,  1895,  p.  532  (1896) 
Decay,  Fomes  fomentarins  (L.)  Fr.  Duggar,  p.  467. 
Gall,  Pycnochylrium  globosum,  Schrot;  Duggar,  p.  139. 
Heart-rot,  Fomes  igniarius  (L.)  Gill.;  Duggar,  p.  465. 
Leaf-blotch,  Rhytisma  acerinum  (Pers.)  Fr. 
Leaf-spot  {Phyllosticta  acericola,  Cke.  &  Ell.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  383-386  (1889). 

Treat,  (rec),  U.  S.  Dep.  Agr.,  Rep.  for  1888,  p.  386  (1889). 
Powdery  Mildew,  Uncintila  aceris  (DC.)  Wint. 
White-rot,  Polyporus  squamosus  (Huds.)  Fr.;  Duggar,  p.  453. 

Melon 

(Cucumis  melo,  L.) 

Anthracnose  (Collclotrichnm  lagenarium  (Pass.)  Ell.  &  Hals.). 
Descr.,  U.  S.  Dep.  Agr.,  Bot.  Div.,  Bull,  8,  p.  64  (1889). 
Descr.  Illus.,  Okla.  Agr.  Exp.  Sta.,  Bull.  15,  pp.  30-31  (1895). 
Treat,  (pos.),  Md-  Agr.  Exp.  Sta.,  Rep.  4,  1891,  p.  387  (1892). 


444  SPECIAL   PLANT    PATHOLOGY 

Anthracnosc  {Collclolrichum  oligochcetum,  Cav.). 
Bacteriosis  or  Wilt  {Bacillus  tracheiphilus,  E.  F.  Sm.). 
Downy  Mildew  {Plasmopara  cubenis  (B.  &  C.)  Humph.). 

Occ.  Descr.,  Conn.  Agr.  Exp.  Sta.,  Rep.  23,  1899,  pp.  277-278  (1900). 
Leaf-blight  {Altcrnarla  hrassica,  Sacc,  var.  nigrescens,  Regel.). 

Descr.,  Conn.  Agr.  Exp.  Sta.,  Rep.  19,  1895,  pp.  186-187  (1896). 
lUus.,  Ohio  Agr.  Exp.  Sta.,  Bull.  73,  pp.  235-236  (1897). 

Treat,  (pos.),  Conn.  Agr.  Exp.  Sta.,  Rep.  22,  '9Sj#%).  229-235  (1899)-. 

Cf.  Conn.  Agr.  Exp.  Sta.,  Rep.  23,  1899,  pp.  270-573  (1900). 
Leaf-spot  {Phyllosticta  cuctirbitacearum,  Sacc.  ?) . 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  p.  355  (1894). 
Scab  {Scolecotrichutn  melophlhorum,  Pr.  &  Del.). 

Soft-rot  (Bacillus  melonis,  Gidd.)  Vt.  Bull.  148,  363-416,  pis.  8  (Jan.  1910). 
Southern  Blight  (Sclerotium  Rolfsii,  Sacc). 
Wilt  (Neocosmospora  vasinfccta  (Atk.)  E.  F.  Sm.). 

Cf.  Conn.  Agr.  Exp.  Sta.,  Rep.  22,  1898,  pp.  227-228  (1899). 

Mesquite 

{Prosopis  juliflora,  DC.) 

Anthracnose  {Glaosporium  leguminum  (Cke.),  Sacc). 

Blight  {Scleropycnium  aureutn,  Heald  &  Lewis).     Trans.  Amer.  Micr.  Soc,  XXX F, 

5-9  (June,  19 1 2). 
Rust  (Ravenelia  arizonica,  Ell.  &  Ev.). 

Mignonette 

{Reseda  odorata,  L.) 

Leaf-blight  {Cercospora  reseda;,  Fckl.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1889,  pp.  429-430  (1890). 
Treat,  (pos.),  U.  S.  Dep.  Agr.,  Rep.  for  1889,  p.  431  (1890). 

Millet 

{Panicum  miliaceum,  L.) 

Purple-spot  {Piricularia  grisea  (Cke.),  Sacc). 
Smut  {Uslilago  Cramcri,  Korn.). 

Mulberry 

{Morus  spp.) 

Die-back  {Myxos  pari  urn  Dledickii,  Syd.). 
Chytridiose  {Cladochytrium  mori,  Prunet.). 

See  U.  S.  Dept.  Agr.,  Exp.  Sta.  Rec,  VI-9,  p.  830  (1895). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  445 

Eye-spot  {Ccrcospora  moricola,  Cke.). 

Leaf-spot  {Ccrcospora  missouriensis,  Wint). 

Rooi-iot  (Hclicobasidium  mompa,Ta.naka..=Scptobasid!nm  mompa  (Tanaka),  Rac.«). 


Mushroom 
(Agariciis  campcslris,  L.) 
Mold  {Mycogone  perniciosa,  Magn.). 

Nasturtium 
{TropceoJtim  majiis,  L.) 

Wilt  {Pscudomonas  solanaccarum,  E.  F.  Sm.). 

Journ.  Agric.  Research  4,  pp.  451-457,  pis.  64  (1915). 
Leaf-blight  {Alternaria  sp.,  and  Pleospora  tropceoli,  Hals.). 

Descr.,  N.  J.  Agr.  Exp.  Sta.  Rep.  13,  1892,  p.  290-293  (1893). 

Oak 

(Quercus  spp.)^ 

Anthracnose  (Gnomonia  veneta  (Sacc.  &  Speg.),  Kleb). 

Pocketed-rot  {Poly poms  pilotce,  Schw.). 

Decay,  or  Brown-rot  {Polyporus  sulphureus  (Bull.)  Fr.). 

Atkinson,  Bull.  193,  Cornell  Agr.  Exp.  Sta.  (June,  1901). 
Heart- rot  {Fames  igniarius  (L.)  Gill.). 
Honeycomb  Heart- rot  {Stcreum  subpileatiim,  B.  &  C). 

Journ,  of  Agr.  Research  V;  421  (Dec.  6,  1915). 
Leaf-curl  {Taphrina  caerulescens,  Desv.  &  Mont.),  Tul. 
Leaf-spot  {Marsonia  quercus,  Pk.}. 

f  {Armillaria  mellea,  Vahl).     Bull.  U.  S.  Dep.  Agr.,  No.  89  (1914). 
{Clitocyhe  parasUica,  Wilcox). 
{Polyporus  dryadetis,  Fr.). 
1^   {Rosellinia  quercina,  Hartig). 
Soft  Rot  {Polyporus  obhisus,  Berk). 
String  and  Ray-rot  {Polyporus  Berkeleyi,  Fr.). 

Straw-colored  Rot  {Polyporus  frondosus,  Fr.),  Journ.  Agr.  Research  I,  109  (1913). 
Tar-spot  {Rhyiisma  erylhrosporum,  Bri.  &  Cav.). 
White-rot  {Polyporus  squamosus  (Huds.)  Fr.). 


Root-rot 


1  Consult  VON  SCHRENK,  HERMANN  and  Spaulding,  Perley:  Diseases  of  De- 
ciduous Forest  Trees.     Bull.  149,  U.  S.  Bureau  of  Plant  Industry,  1909. 


446  SPECIAL  PLANT   PATHOLOGY 

Oats 

(Aiena  saliva,  L.) 

Blight  (Bacterial)  Pseudomonas  avence,  Manns. 

Descr.,  Journ.  Mycol.,  Vol.  VI,  p.  72;  Ohio  Bull.  210,  Oct.   1909,  pp.  91-167, 
pis.  IS  (1890). 
Leaf-spot  {Phyllosticla  sp.). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  p.  319  (1895). 
Mildew  {Helminthosporium  inconspicuum,  Cke.  &  Ell.,  var.  hrillanicum  Gr.,  and 
Cladosporiiim  herbarum  (Pers.),  Lk.). 
Descr.,  Me.  Agr.  Exp.  Sta.,  Rep.  for  1894,  pp.  95-96  (1895). 
Rust  {Puccinia  coronata,  Cda.,  and  P.  graminis,  Pers.). 
See  Wheat  (Rust). 

Cf.  U.   S.  Dep.  Agr.,   Div.  Veg.  Phys.  &  Path.,  Bull.  16,  pp.  45-52  &  60-65 
(1899). 
Smut  (Uslilago  avena  (Pers.),  Jens,  and  U.  levis  (Kell.  &  Sw.)  Magn.). 

Descr.  lUus.,  Kan.  Agr.  Exp.  Sta.,  Rep.  2,  1889,  pp.  215-238  &  259-260  (1890). 
Ohio  Agr.  Exp.  Sta.,  Bull.  64,  pp.  123-126  (1896). 
111.  Agr.  Exp.  Sta.,  Bull.  57,  pp.  297-298  (1900). 
Treat  (pos.),  U.  S.  Dep.  Agr.,  Farm.  Bull.  75,  pp.  11-16  (1898). 
111.  Agr.  Exp.  Sta.,  Bull.  57,  pp.  309-316  (1900). 

Okra 

(Hibiscus  esculentus,  L.) 

Root- rot  (Ozonium  omnivorum,  Shear). 

Wilt  {Fusarium  vasinfedum  =  Neocosmos pora  vasinfcclum  (Atk.),  E.  F.  Sm.). 
See  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys."  &  Path.,  Bull.  17,  p.  31  (1899). 

Cf.  N.  Car.  Rep.  191 1,  pp.  70-73,  figs.  4. 
{Verticillium  albo-alrmn,  Reinke  &  Berthold)  Phytopathology  IV,  p.  393  (De- 
cember, 1914). 

Oleander 

{Neritim  oleander,  L.) 

Leaf-spot  (Macrosporium  nerii,  Cke.). 

Bull.  218,  CaHf.  Agric.  Exper.  Sta.  (June,  191 1). 

Olive 

(Oka  europcea,  L.) 

Anthracnose  {Glosospormm  olivarum,  d'Almeida). 

Fruit-mold  or  Dry-rot  (Alternaria  sp.  and  Macrospoxium  sp.). 

Descr.  lUus.  Cal.  Agr.  Exp.  Sta.,  Rep.  for  '95-'97,  pp.  235-236  (1898). 


LIST   OF   SPECIFIC  DISEASES   OF  PLANTS  447 

Knot  (Pseudomonas  Savastonoi,  E.  F.  Sm.). 

Cook  Diseases  of  Tropical  Plants,  p.  144  (1913). 
Rot  (Bacterial). 

Descr.,  Cal.  Agr.  Exp.  Sta.,  Bull.  123,  p.  19  (1899). 
Scab,  Peacock  Leaf-spot  {Cycloconium  oleaginum,  Cast.). 

Descr.,  Cal.  Agr.  Exp.  Sta.,  Rep.  1892-93,  pp.  297-298  (1894). 

See  U.  S.  Dep.  Agr.,  Exp.  Sta.  Rec,  XI-6,  p.  554  (1900). 
Sooty- mold  (Meliola  sp.,  Syn.  Capnodlunt  cilri  Berk.  &  Desm.). 
Tuberculosis  {Bacillus  clece  (Arcang.)  (Trev.). 

Descr.  Illus.,  Cal.  Agr.  Exp.  Sta.,  Bull.  120  (1898). 

Treat,  (rec),  Cal.  Agr.  Exp.  Sta.,  Bull.  120,  pp.  lo-ii  (1898). 

Cf.  Cal.  Agr.  Exp.  Sta.,  Rep.  for  '97-'98,  p.  178  (1900). 

Onion 
{Allium  cepa,  L.) 

Anthracnose  or  Rot  {Vermicular ia  circinans,  Berk). 

Descr.  Illus.,  Conn.  Agr.  Exp.  Sta.,  Rep.  13,  1889,  p.  163  (1890). 

Treat,  (rec),  Conn.  Agr.  Exp.  Sta.,  Rep.  13,  1889,  pp.  164-165  (1890). 
Downy  Mildew  {Peronospora  Schleideniana,  deBy.). 

Descr.  Illus.,  Wis.  Agr.  Exp.  Sta.,  Rep.  i,  1883,  pp.  38-44  (1884). 

Descr.,  Conn.  Agr.  Exp.  Sta.,  Rep.  13,  1889,  pp.  155-156  (1890). 

N.  Y.  Cornell  Bull.  218,  pp.  137-161,  figs.  17  (Apr.,  1904). 

Treat,  (rec),  Vt.  Agr.  Exp.  Sta.,  Rep.  10,  1896-97,  pp.  61-62  (1897). 
Mold  {Macrosporium  sarcinula,  B.,  var.  parasiticum,  Thiim.,  and  M.  Porri,  Ell.). 

Descr.  Illus.,  Conn.  Agr.  Exp.  Sta.,  Rep.  13,  1889,  pp.  158-162  (1890). 

Treat,  (rec),  Conn.  Agr.  Exp.  Sta.,  Rep.  13,  1889,  p.  i6r  (1890). 
Rot  (Bacterial). 

Descr.  Illus.,  N.  Y.  Agr.  E.xp.  Sta.,  Bull.  164,  pp.  209-212  (1899). 
Smut  {Urocyslis  cepula,  Frost). 

Descr.  Illus.,  Conn.  Agr.  Exp.  Sta.,  Rep.  13,  1889,  pp.  129-146  (1890). 

Ohio  Bull.  122,  pp.  71-84,  figs.  4  (Dec,  1900). 

Treat,  (pos.),  Conn.  Agr.  Exp.  Sta.,  Rep.  13,  1889,  pp.  147-153  (1890). 

(By  transplanting),  Conn.  Agr.  Exp.  Sta.,  Rep.  19,  1895,  pp.  176-182 

(1896). 
Cf.  U.  S.  Dep.  Agr.,  Farm.  Bull.  39,  pp.  16-20  (1896). 
N.  Y.  State  Bull.  182,  pp.  145-172,  pi.  i  (Dec,  1900). 

Orange 

{Citrus  aurantium;  L.) 

Anthracnose  {Collelotrichum  gloeosporioides  Penz.). 

Descr.  Illus.,  Fla.  Agr.  Exp.  Sta.,  Bull.  53,  pp.  171-173  (1900).    . 

Fla,  Agr.  E.xp.  Sta.,  Bull.  108,  pp.  25-47  (Nov.,  191 1). 


448  SPECIAL  PLANT   PATHOLOGY 

Treat,  (rec),  Fla.  Agr.  Exp.  Sta.,  Bull.  53,  p.  173  (1900). 
Black-rot  {AUcrnaria  citri  Ellis  &  Pierce). 

Colt,  Citrus  Fruits,  p.  388  (1Q15). 
Cottony- mold  and  Twig-blight  {Sdcrotinia  libcrliana,  Fkl.). 

Coit,  Citrus  Fruits,  p.  382  (1Q15). 
Diplodia  Rot  {Diptodia  natalensis  Evans),  Coit,  p.  397  (1915). 
Flyspeck  {Leptothyrium  pomi  (Mort  &  Fr.)  Sacc.)  Hume,  Citrus  Fruits  and   Their 

Culture,  p.  481  (191 1 ). 
Foot-rot  or  Mal-di-gomma  {Fusarium  limonis,  Bri.). 

Descr.  Illus.  Treat,  (rec),  U.  S.  Dept.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  8, 
pp.  28-31  (1896J. 
Fla.  Agr.  Exp.  Sta.,  Bull.  53,  pp.  151-155  (1900). 
Fruit-rot  {Penicilliiim  digitatum.  (Fr.),  Sacc.  &  Penicillium  Ualicum,  Wehm.). 
Gum-disease  {Bolrytis  vulgaris,  Fr.). 

Coit,  Citrus  Fruits,  p.  366  (1915). 
Leaf-glaze  {Strigula  complanata,  Fee). 

Occ,  Journ.  Mycol.,  Vol.  VII,  p.  36  (1891). 
Melanose  {Phomopsis  citri  Fawcett). 

Descr.  Illus.  Treat,  (pos.),  U   S.  Dept.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  8, 
PP-  33-38  (1896). 
Nail-head  Rust   {Cladosporium   hcrharum    (Pers.),    Pk.   var.  citricolum  Fawcett  & 
Berger). 

Coit,  Citrus  Fruits,  p.  395,  1915,  Fla.  Bull.  109,  pp.  47-60  (May,  191 2). 
Scab  {Cladosporium  citri  Mass.). 

Phytopath.  6,  pp.  127-142  (1916). 

See  Lemon  (scab.). 
Sooty-mold  {Meliola  Penzigi,  Sacc.  and  M.  camellice  (Catt.),  Sacc. 

Descr.  Illus.  Treat,  (pos.),  U.  S.  Dept.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  13 
(1897). 
Toadstool  Root-rot  (Armillaria  mcllea  Vahl.). 

Coit,  Citrus  Fruits,  p.  373  (1915). 
Trunk-rot  {Schizophyllum  commune  Fr.). 

Coit,  Citrus  Fruits,  p.  399  (191 5). 
Wither-tip  (Colletotrichum  gloeosporioides,  Penz.). 

Coit,  Citrus  Fruits;  380  (1915). 

Grossenbacher,  J.  G.;  Some  Bark  Diseases  of  Citrus  Trees  in  Florida,  Phyto- 
path. 6,  pp.  29-50  (1916). 


Orch.xrd  Grass 

{Dactylis  glomcrala,  L.) 

Puccinia  coronata,  Cda.;Duggar,  p.  420  (1909) 
Puccinia  graminis,  Pers.;  Duggar,  p.  408  (1909^ 
Scolecotrichose  {ScoJetotrichum  graminis  Fuckl.). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  449 

ORCHros 
(Orckidacca) 

Anthracnose  {Glceosporium  cincliim  Bri.  &  Cav.  Colletotrichum  cinclum  (Bri.  &  Cav.) 
Stonem.). 
Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  pp.  414-417  (1894). 
Anthracnose  {Glceosporium  macro  pus,  Sacc). 
Leaf-blight  {Ccrcospora  angrcci,  Feuill  &  Roum.). 

Osage  Orange 
(Toyxlon  pomiferum,  Raf.) 

Rust  {Physopella  ficl  (Cast),  \rt\\.  =  U redo  fici  Cast.) 
Blight  {Sporodesmium  maclurcr  Thiim. 

Palm 

(Phoenix   dactylifera,  L.) 

Leaf-spot  (Graphiola  plicenicis  (Moug.)  Poit.). 
Bull.  218,  Calf.  Agr.  E.xp.  Sta.  (June,  191 1). 

Pansy 

{Viola  tricolor,  L.) 

Leopard  Petal-blight  {Colletotrichum,  viola-iricoloris),  R.  E.  Smith. 

Smith,  R.  E.,  Bot.  Gaz.  27,  p.  203  (March,  1899). 
Dry-up  {Fusarium  djo/(5  Wolf.). 

Wolf,  F.  A.;  Mycologia,  2,  p.  19  (January,  igio). 

Papaw 

{Carica  papaya,  L.) 
Leaf-spot  {Pucciniopis  caricce  Earle). 

Parsnip 
{Paslinaca  saliva,  L.) 

Leaf-blight  {Cercospora  apU,  Fres.j. 

Occ,  N.  J.  Agr.  E.Kp.  Sta.,  Rep.  15,  1894,  p.  351  (1895). 
Root-rot  {Corticium  vagum,  Bri.  &  Cav.,  var.  solani,  Burt.). 

Heald  &  Wolf,  Plant  Disease  Survey  in  Texas  (191 2). 
29 


4SO  SPECIAL  PLANT  PATHOLOGY 

Pea 

[Pisum  salivuni,  L.) 

Damping-off  {Ascochyla  pisi,  Lib.  and  Pylhium  sp.). 

Occ,  Conn.  Agr.  Exp.  Sta.,  Rep.  23,  1899,  pp.  280-281  (1900). 

Ohio  Bull.  173,  pp.  231-246,  figs.  II  (Apr.,  1906). 
Pod-spot  {Ascochyta  pisi,  Lib.). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  p.  358  (1894). 

Treat.  (rec.J,  Del.  Agr.  Exp.  Sta.,  Bull.  41,  pp.  9-1 1  (1898). 
Leaf-spot  {Septoria  pisi,  West.). 

-  Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  p.  358  (1894). 
Mold  {Pleospora  pisi  (Sow.),  Fckl.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  p.  358  (1894). 
Powdery  Mildew  {Erysiphe  polygoni,  DC). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  p.  357  (1894). 

Peach 
{Primus  persica,  Benth.  &  Hook) 

Anthracnose  {Glceosporium  laeticolor.  Berk.). 

Occ.  Ohio  Agr.  Exp.  Sta.,  Bull.  92,  p.  225  (1898). 
Brown-rot  {Sclerotinia  cinerea  (Bon.)  Schrot.)  Heald,  F.  W.,  Washington  Agricul- 
turist, VIII,  No.  9,  June,  191 5. 
Crown-gall  (Pseiidomonas  tumejaciens,  E.  F.  Sm.  and  Towns.). 
Die-back  {Valsa  leucostoma  (Pers.)  Fr.). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  129  (1910). 
California  Peach  Blight  {Coryneum  Beijerinckii  Oud.). 

Oregon  Stat.  Biennial  Report,  p.  255  (1911-12). 
Cal.  Bull.  191,  pp.  73-98,  figs.  17  (Sept.,  1907). 
Frosty  Mildew  {Cercosporella  persica,  Sacc). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  133  (1910). 
Fruit-mold  or  Twig-blight  {Sclerotinia  friicligena  (Pers.)  Schrot.). 

Descr.  Illus.,  Journ.  Mycol.,  Vol.  VII,  pp.  36-38  (1891). 
Ga.  Agr.  Exp.  Sta.,  Bull.  50  (1900). 

Treat,  (pos.),  Ga.  Agr.  Exp.  Sta.,  Bull.  50,  pp.  267-269  (1900). 
Cf.  Conn.  Agr.  Exp.  Sta.,  Rep.  24,  1900,  pp.  252-254  (1901). 

Cf.  Cherry  (Fruit-mold  and  Twig-blight). 
Pustular-spot  {Helminthosporitim  carpophilum,  Lev.). 

Occ,  Mich.  Agr.  Exp.  Sta.,  Bull.  103,  p.  57  (1894). 

Treat,  (pos.),  Ohio  Agr.  Exp.  Sta.,  Bull.  92,  p.  225  (1898). 
Leaf-blight  or  Shot-hole  {Cercosporella  persica,  Sacc). 

Occ,  N.  C.  Agr.  Exp.  Sta.,  Bull.  92,  p.  103  (1893). 

Treat,  (rec),  N.  C.  Agr.  Exp.  Sta.,  Bull.  92,  p.  103  (1893). 
Leaf -blight  or  Frosty  Mildew  {Cercosporella  persica,  Sacc). 

Occ,  Journ.  Mycol.,  Vol.  VII,  p.  91  (1892). 


LIST   OF    SPECIFIC   DISEASES    OF   PLANTS  451 

Leaf-curl  {Exoascus  deformans  (Berk.),  Fckl.). 

Descr.  Illus.,  N.  Y.  (Corn,  Univ.)  Agr.  Exp.  Sta.,  Bull.  73,  pp.  324-325  (1894)- 

U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  20  (1900). 
Treat,  (pos.),  N.  Y.  Cornell  Bull.  276,  p.  151-178,  figs/s  (Apr.,  1910). 
U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  20  (1900). 
Powdery  Mildew  {Spharolhcca  pannosa  (Wallr.),  Lev.  ?  and  Podospkcsra  oxyacantha 
(DC),  de  By.). 
Occ,  Journ.  Mycol.,  Vol.  VII,  p.  90  (1892). 

Descr.  Illus.,  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  74,  p.  381  (1894). 
Root-rot  {Fungus  indet.?). 

Occ,  Journ.  Mycol.,  Vol.  VII,  p.  377  (1894). 

Ohio  Agr.  Exp.  Sta.,  Bull.  92,  p.  23s  (1898). 
Rust  {Puccinia  pruni-persicce  Hori). 

Phytopath.  2,  p.  143-145,  also  Tranzschelia  punctata  (Pers.)  Arth. 
2d  Biennial  Crop  Pest  and  Hort.  Rep.  Oregon  (June,  1915). 
See  Cherry  (Rust). 
Scab  {Cladosporium  carpophilum,  Thiim). 

Descr.  Illus.,  Ind.  Agr.  Exp.  Sta.,  Bull.  19,  pp.  5-8  (1889). 

Del.  Agr.  Exp.  Sta.,  Rep.  8,  1895-96,  pp.  60-63  (1896). 
Ohio  Agr.  Exp.  Sta.,  Bull.  92,  pp.  220-222  (1898). 
Treat,  (pos.),  Del.  Agr.  Exp.  Sta.,  Rep.  8,  1895-96,  p.  63  (1896). 
Cf.  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  pp.  328-330.     (On  leaves). 
Conn.  Agr.  Exp.  Sta.,  Rep.  20,  1896,  pp.  269-271.     (On  twigs). 
Bull.  395,  U.  S.  Dept.  Agric,  1917. 
Shot-hole  {Coryneum  Beijcrinckii  Oud.). 

Stevens  &  Hall,  Disease  of  Economic  Plants,  p.  129  (1910). 
Stem-blight  {Phoma  persicce,  Sacc). 

Descr.  Illus.,  Ohio  Agr.  Exp.  Sta.,  Bull.  92,  pp,  233-234  (1898). 
Yellows. 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  135  (1910). 


Peanut 
{Arachls  hypogcea,  L.) 

Bacterial  Blight  {Bacillus  solanacearum,  E.  F.  Sm.). 

Phytopathology  IV;  397  (December,  19 14). 
Leaf-spot'  {Cerccspora  personata  (Bri.  &  Cav.),  Ell.  &  Ev.). 

Phytopathology  IV;  397  (December,  19 14). 
Red-rot  {Neocosmopora  vasinfecta  (Atk.)  E.  F.  Sm.). 

Phytopathology  IV;  397  (December,  1914). 
Sclerotial-rot  {Sclerotium  Rolfsii  Sacc). 

Phytopathology  IV;  397  (December,  19 14). 

'  Consult  also  Wolf,  Frederick  A. :  Further  Studies  on  Peanut  Leaf-spot. 
Journ.  Agr.  Res.  5,  pp.  891-902,  Feb.,  1916. 


452  SPECIAL   PLANT   PATHOLOGY 


{Pirns  conimunis,  L.) 

Anthracnose  {Collclotrichum  sp.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  p.  331  (1895). 
Bitter- rot  (Glomcrella  rufomaculans  (Berk.),  Spauld.  &  v.  Schr.). 
Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  107  (1910) 
RIack-rot  {Spharopsis  malormn,  Berk.). 
Brown-blotch  (Macros porium  Sydowianum,  Farneti). 

Circ.  52,  N.  J.  Agr.  E.xp.  Sta. 
Body-blight  or  Canker  (Spkacropsis  malar  urn,  Berk.). 

Occ,  N.  Y.  Agr.  E.xp.  Sta.,  Bull.  163,  p.  203  (1899).  . 
Dry-rot  {Thelephora  pediceUata,  Schw.). 

Descr.,  Journ.  Mycol.,  Vol.  VI,  pp.  113-114  (1891). 
Treat,  (pos.),  Journ.  Mycol.,  Vol.  VI,  p.  114  (1891). 
Fire-blight  {Bacillus  amylovorus  (Burr.),  Trev.). 

Descr.  Illus.,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  5,  1886,  pp.  275-289  (1887). 
Descr.,  Conn.  Agr.  Exp.  Sta.,  Rep.  18,  1894,  pp.  113-116  (1895). 
U.  S.  Dept.  Agr.,  Year-book  for  1895,  pp.  295-298  (1896). 
N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  145,  pp.  622-625,  1898. 
Utah  Bull.  85,  Nov.,  1903,  pp.  45-52. 
Vt.  Rep.  1902,  pp.  231-239. 
Ark.  Bull.  113,  1913,  pp.  493-505. 
Treat,  (pos.),  Phytopath.  6,  pp.  152-158,  288-292  (1916). 
Fly-speck  {Leptothyriurn  carpophilitm,  Pass.). 

N.  J.  Agr.  Exp.  Sta.,  Rep.  18,  1897,  pp.  378-383  (1898). 
Fruit  Spot  {Fabrcea  maculatum,  (Lev.),  Atk.). 

Leaf-blight  {FabrcRa     maculaium  (Lev.),  Atk.  and  Cercospora  minima,  Tracy  and 
Earle). 
Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  357-362  (1889). 
Del.  Agr.  Exp.  Sta.,  Bull.  13,  pp.  4-6  (1891). 
N.  Y.   (Corn.   Univ.)   Agr.  Exp.   Sta.,   Bull.   145,  p.  611  (1898). 
Heald  and  Wolf,  Plant  Disease  Survey,  San  Antonio,  Texas, 
(1912). 
Treat  (pos.),  R.  L  Agr.  E.xp.  Sta.,  Bull.  31,  pp.  5-9  (1895). 
Cf.  Quince  (Leaf-spot). 
Leaf-spot  {Septoria  piricola,  Desm.). 

Descr.  Illus.,  Treat,  (pos.),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  145,  pp. 
597-611  (1898). 
Rust  {Gymnos porangium  globosum,  Farl.). 

Occ,  Conn.  Agr.  Exp.  Sta.,  Rep.  14,  1890,  p.  98  (1891). 
Scab  {Fusicladinm  pirinmn  (Lib.),  Fckl.  =  Ventnria  pirina,  Aderh.). 

Descr.  Illus.,  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  145,  pp.  616-620  (1898). 
Treat,  (pos.),  Vt.  Agr.  Exp.  Sta.,  Bull.  44,  pp.  85-90  (1895). 
Cf.  Apple  (Scab). 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  453 

Shot-hole  {CyHndrosporium  padi,  Karst.). 

Bull.  212,  Colo.  E.xp.  Sta.  (October,  1915). 

Pecan 

(Iliioria  pcain  (Marsh.),  Butt.)i 

Anthracnose  (Glomerella  cingulata  (Stonem)  S.  &  S.). 
Brown  Leaf-spot  {Ccrcospora  fusca,  Rand). 
Crown-gall  (Pseudomonas  tumefaciens,  E.  F.  Sm.  &  Towns.). 
Kernel -spot  (Coniothyrium  caryogenum,  Rand). 
Leaf-blight  {Septoria  carya,  Ell.  &  Ev.). 

Heald  &  Wolf,  Plant  Disease  Survey  in  Texas  (191 2). 
Leaf -blotch  (Mycosphcerella  convcxula  (Schw.),  Rand). 

Phytopath.  i,  pp.  133-138  (iQ")- 
Mildew  {Micros phccra  alni  (Wallr.),  Wint. 
Nursery-blight  {Phyllosticia  caryce,  Pk). 
Scab  {Fiisidadium  effiisiim,  Wint.). 

Orton,  W.  A.,  Science,  new  ser.  21,  p.  503  (March  31,  1905). 

Peony 

{Pceonia  officinalis,  L.) 

Mold  {Botryiis  pceonia,  Oud.) 

Peppers 

{Capsicum  anmmm,  L.) 

Anthracnose  {Colletolrichnm  nigrum,  Ell.  &  Hals,  and  Glmosporium  piperalim,  Eil. 
&  Ev.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  pp.  358-359  (1891). 

Cf.  N.  J.  Agr.  Exp.  Sta.,  Rep.  13,  pp.  ^^2-7,31  (1893)- 
Fruit-rot  {Glceosporium  piperatum,  Ell.  &  Ev.). 
Mold  {Macros porium  sp.). 

Occ,  N.  J.  Agr.  E.xp.  Sta.,  Rep.  15,  1894,  p.  351  (1895). 
Leaf-spot  {Ccrcospora  capsici,  Heald  &  Wolf). 

Persimmon 

{Diospyros  spp.) 

Black  Leaf-spot  {Ccrcospora  fuliginosa.  Ell.  &  Kellem). 
Leaf-spot  {Ccrcospora  kaki,  Ell.  &  Ev.). 
Fruit- rot  {Phyllosticia  biformis,  Heald  &  Wolf). 

1  Rand,  Frederick  V. :  Some  Diseases  of  Pecans,  Journal  of   Agricultural  Re- 
search I,  pp.  303-337,  June  ID,  1914. 


454  SPECIAL   PLANT   PATHOLOGY 

{Agaricus. 
Ccrcospora  air  a,  EH.  &  Ev. 
Glososporium  diospyri,  EH.  &  Ev. 
See  N.  C.  Agr.  Exp.  Sta.,  Bull.  92,  p.  116  (1893). 

Phlox 
(Phlox  spp.) 
Leaf-spot  {Scptoria  divaricala,  Ell.  &  Ev.). 

Pine 

{Pinus  spp.)i 

Blister-rust  {Cronartium  ribicola,  Fisch.  (=  Peridermium  slrobi  (Kleb.),  Spauld.). 
Bull.  206,  Bureau  of  Plant  Industry,  191 1;  American  Forestry  (Feb.,  Dec, 
1916). 
Bluing  (Ceraloslomdlapilif era  (Fr.)Wmt.). 

von  Schrenk,  U.  S.  Bureau  Plant  Industry,  Bull.  36  (1903). 
Chalky  Quinine  Fungus  (Fames  laricis  (Jacq.),  Murr.). 

Meinicke,  1914,  p.  44. 
Dry-rot  (Trametes  Pini  (Brot.)   Fr.,  and   T.   radiciperda  'H.axiig  =Fomes  annosiis 
(Fr.),  Cke.). 
Descr.  Illus.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  25,  pp.  31-40 
(1900). 
Gray  Leaf- tip  (Hypoderma  Desmazicri,  de  By.). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  445  (1910). 
Leaf-blight    (Lophodermium     brachysporum,    Rostr.   =  Hypoderma     hrachysporum 
(Rostr.),  Tubeuf.). 
Stevens  &  Hall,  p.  445  (1910). 
Needle  Disease  (Hypoderma  deformans,  Weir  on  Finns  ponderosa,  Laws.  Journ.  Agric. 

Res.  VI:  277-288,  May  22,  1916). 
Pine  Gall  (Peridermium  Harknessii  Moore =P.  cerebrum  Pk.). 

Meinecke,  E.  P.,  Forest  Tree  Diseases  Common   in    California   and    Nevada, 
U.  S.  Forest  Service  (1914). 
Punk-rot  (Polyporus  pinicola,  Aik.^Fomes  ungulalus  (Schraeff)  Sacc). 

Bull.  193,  Corn.  Univ.  Agr.  Exp.  Sta.  (June,  1901). 
Red-rot  (Polyporus  ponderosus,  v.  Schr.). 

U.  S.  Bureau  of  Plant  Industry,  Bull.  36  (1903). 
Root- rot  (Polyporus  Schweinitzii,  Fr.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  25,  pp.  18-24  (1900). 

*  The  twelve  species  of  Peridermium  found  in  American  pines  are  described  by 
Arthur  and  Kern  in  North  American  Species  of  Peridermium,  Bull.  Torr.  Bot. 
Club  33,  pp.  403-438,  1906. 


LIST   OF   SPECIFIC   DISEASES    OF   PLANTS  455 

Rust   {Coleosporium  pini,  GaX\=Gallowaya    pinl  (GalL),  Arth.   and    Peridennium 
piriforme,  Pk.). 
Descr.,  Journ.  Mycol.,  Vol.  VII,  p.  44  (1891). 
Wet- rot  (Polyporus  subacidus,  Pk.  ?). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  25,  pp.  44-49. 
(1900). 

Pink  (Sweet  William) 

(Dianthus  barbalus,  L.) 

Mold  (Heterosporium  echinulalum  (Berk.),  Cke.). 
Rust  {Puccinia  arenarice  (Schum.),  Wint.). 

Descr.  lUus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  13,  1892,  pp.  278-280  (1893). 

Treat,  (rec),  N.  J.  Agr.  Exp.  Sta.,  Rep.  13,  1892,  p.  280  (1893). 

Plum 

{Primus  spp.) 

Bacterial  Leaf-spot  (P^ez^/owoHd^ />«<;»",  E.  F.  Sm.). 

Heald  &  Wolf,  Plant  Disease  Survey,  San  Antonio,  Texas  (191 2). 
Black-knot  (Plourightla  morbosa  (Schw.),  Sacc). 

Descr.  Illus.  Treat.,  Ky.  Agr.  Exp.  Sta.,  Bull.  80,  pp.  250-256  (1899). 

Cf.  Cherry  (Black  Knot). 
Canker  (Neclria  ditissima,  Tul.). 

Descr.,  See  U.  S.  Dep.  Agr.,  Exp.  Sta.  Rec,  IX-8,  pp.  761-762  (1898). 
Die-back  {Valsa  leticostoma  (Pers.),  Fr.). 

Heald  &  Wolf,  Plant  Disease  Survey,  San  Antonio,  Texas  (191 2). 
Fire-blight  (Bacterial). 

Occ,  Conn.  Agr.  Exp.  Sta.,  Rep.  18,  1894,  pp.  117-118  (1895). 
Fruit-mold  {Sclerotinia  frnctigena,  Kze.  &  Schm.). 

Descr.  Illus.,  Oreg.  Agr.  Exp.  Sta.,  Bull.  57,  pp.  3-12  (1899). 

Treat,  (pos.),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  86,  pp.  71-72  (1895). 
Mo.  Agr.  Exp.  Sta.,  Bull.  31,  pp.  16-18  (1895). 

Valleau,  W.  D.:  Varietal  Resistance  of  Plums  to  Brown  Rot,  Journ.  Agr.  Re- 
search V,  pp.  365-395  (1915)- 

Cf.  Cherry  (Fruit-mold). 
Leaf-curl  {Exoascus  mlrabllis,  Atk.). 

Descr.  Illus.,  Conn.  Agr.  Exp.  Sta.,  Rep.  19,  1895,  pp.  183-185  (1896). 

Treat,  (pos.).  Conn.  Agr.  Exp.  Sta.,  Rep.  20,  1896,  p.  281  (1897). 
Leaf-spot  {Cylindrosporium  padi,  Karst.  and  Phyllostida  congesta,  Heald  &  Wolf). 

Descr.  Illus.,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  5,  1886,  pp.  293-296  (1887). 
N.  Y.  Agr.  Exp.  Sta.,  Rep.  6,  1887,  pp.  347-35©  (1888). 

Treat,  (pos.),  U.  S.  Dep.  Agr.,  Div.  Veg.  Path.,  Bull.  7,  p.  30  (1894). 
N.  Y.  Agr.  Exp.  Sta.,  Rep.  15,  '96,  pp.  384-401  (1897). 

Cf.  Cherry  (Leaf -spot). 


456  SPECIAL   PLANT   PATHOLOGY 

Plum-pockets  {Exoascus  pruni,  Fckl.). 

Descr.  lUus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  366-369  (1889). 

N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  73,  pp.  329-330  (1894), 

Treat,  (rec),  N.  C.  Agr.  Exp.  Sta.,  Bull.  92,  p.  iii  (1893). 
Powdery  Mildew  {Podosphccra  oxyacanthcB  (DC),  de  By.). 

See  Cherry  (Powdery  Mildew). 
Root-rot  {Armillaria  mellea,  Vahl). 

Bull.  59,  pp.  14  (1903). 
Rust  {Puccinia  pruni  spinosa,  Fers.  =  Tranzschelia  punclala  (Pers.),  Arth.). 

Descr.,  Journ.  Mycol.,  Vol.  VII,  pp.  354-356  (1894). 

Treat,  (pos.),  Journ.  Mycol.,  Vol.  VII,  pp.  356-362  (1894). 

Cf.  Cherry  (Rust). 
Scab  {Clados pori urn  carpophilum,  Thiim). 

Descr.,  Journ.  Mycol.,  Vol.  VII,  pp.  99-100  (1892). 

Descr.  Illus.,  Iowa  Agr.  Exp.  Sta.,  Bull.  23,  pp.  918-920  (1894). 

Cf.  Cherry  and  Peach  (Scab). 
Shot-hole  (Cylindros porium  padi,  Karst). 

Pomegranate 
{Punka  granatum,  L.) 
Leaf-spot  {Ccrcospora  lylhraccarum,  Heald  &  Wolf). 

Pomelo 

(Citrus  decumana,  Murr.) 

Anthracnose  (CoUctotrichum  glceosporioides,  Penz.). 

Fla.  Bull.  74,  pp.  159-172,  jdIs.  4  (August,  1904). 
Canker  {Pscudomonas  citri,  Hasse). 

Journ.  Agr.  Research  VI,  pp.  69-99  (April,  1916). 

Poplar 
{Populus  spp.) 

Anthracnose  (Marssonia  populi  (Lib.),  Sacc). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  pp.  394-396  (1895). 
Leaf-spot  (Septoria  musiva,  Pk.)  and  {Septoria  populicola,  Pk.). 
Rust  (Melampsora  populina  (Jacq.),  Lev.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  390-392  (1889). 

Treat,  (pos.),  Mass.  Agr.  Exp.  Sta.,  Rep.  7,  1894,  p.  20  (1895). 

Potato  : 

{Solanum  tuberosum,  L.) 

Anthracnose  {Vcrmicularia,  sp.). 
Black-leg  {Bacillus  phylophlhorus,  Appel). 

Orton,  W.  A.,  Potato  Tuber  Diseases,  Farmers'  Bull.  544  (1913). 


LIST   OF    SPECIFIC   DISEASES    OF    PLANTS  457 

Blight  (Bacillus  solanaccamm,  E.  F.  Sm.). 

Descr.  Illus.  Treat,  (rec),  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  12 
(1896). 
Chytridiose  or  Black  Scab  (Synchytriutn  cndohioikum  (Schilb.)  Vcxa\a.l  =  Chryso- 

phlyclis  cndohioiica,  Schilb.) 
Downy  Mildew  or  Rot  {Phytophthora  infcslans,  de  By.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  337~33S  (1889). 
N.  H.  Agr.  Exp.  Sta.,  Bull.  22,  pp.  3-5  (1894). 
N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  113,  pp.  249-254  (1896). 
Vt.  Bull.  168,  pp.  100,  pis.  10,  figs.  10  (August,  191 2). 
Conn.  Rep.,  pt.  10,  pp.  753-774  (1909)- 

Melhus,   I.   E.,   Hibernation   in   the  Irish   Potato,   Journ.   Agr. 
Research  V,  pp.  71-102  (1915). 
Treat,  (pos.),  U.  S.  Dep.  Agr.,  Farm.  Bull.  91  (1899). 
Dry-rot  {Fusarium  solani  (Mart.)  Sacc.  and  F.  radicicola,  WoUenw.). 

Occ,  111.  Agr.  Exp.  Sta.,  Bull.  40,  p.  139  (1895). 
Internal  Browning  (Bacterial  ?). 

Descr.,  111.  Agr.  Exp.  Sta.,  Bull.  40,  pp.  138-139  (1895). 
N.  Y.  Agr.  Exp.  Sta.,  Bull.  loi,  pp.  78-83  (1896). 
Leaf-blotch  {Cercospora  concors  (Casp.)  Sacc). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  278  (1910). 
Leaf-mold  or  Early-blight  (AUernaria  solani  (Ell.  &  Mart.),  Jones  &  Grout). 
Descr.  Illus.,  Del.  Agr.  Exp.  Sta.,  Rep.  4,  1891,  pp.  58-59  (1892). 

N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  140,  p.  393  (1897). 
Vt.  Agr.  Exp.  Sta.,  Bull.  72,  pp.  16-25  (1899). 
Treat,  (pos.),  U.  S.    Dept.  Agr.,  Farm.  Bull.  91,  pp.  5-7  (1899). 
Wise.  Rep.,  pp.  343-354,  figs.  7  (1907)- 
Leak  (Pylhium  de  Baryaniim,  Hesse.) 

Journ.  Agr.  Research  VI,  pp.  627-640,  pi.  i  (1916). 
Powdery^  Scab  {Spongospora  siihkrranea). 

Orton,  W.  A.,  Potato  Tuber  Diseases,  U.  S.  Farm.  Bull.  544  (1913)- 
Bull.,  U.  S.  Dept.  Agr.,  No.  82  (1914). 
Powdery  Dry-rot  {Fusarium  Iriclwlhecoides  Wollenw.). 
Orton,  W.  A.,  U.  S.  Farm.  Bull.  544  (1913). 
Pratt,  Journ.  Agric.  Res.,  VI:  817-831,  Aug.  21,  1916. 
Root-rot  {Entorrhiza  solani,  Fautr.). 

See  U.  S.  Dept.  Agr.,  Exp.  Sta.  Rec,  VII-io,  p.  873  (1896). 
Scab  (Actinomyces  chrcmogenes,  Gasp.). 

Descr.  Illus.,  Conn.  Agr.  Exp.  Sta.,  Rep.  14,  1890,  pp.  81-95  (1891). 
Descr.  Illus.,  Conn.  Agr.  Exp.  Sta.,  Rep.  15,  1891,  pp.  153-160  (1892). 

1  Carpenter,  C.  W.:  Some  Potato  Tuber-rots  Caused  by  Species  of  Fusarium, 
Journal  of  Agricultural  Research  V,  pp.  183-209  (Nov.  i,  1915). 

^  Consult  Melhus,  I.  E.,  Rosenbaum,  J.  and  Schultz,  E.  S.:  Studies  of  Spon- 
gospora subterranea  and  Phoma  tuberosa  of  the  Irish  Potato,  Journ.  Agr.  Research 
Vn,  pp.  213-253,  October,  1916,  also  IV,  pp.  265-278. 


458  SPECIAL  PLANT  PATHOLOGY 

Cf.  W.  Va.  Agr.  Exp.  Sta.,  Sp.  Bull.  2,  pp.  97-111  (iSqS). 

Treat,  (pos.)  Journ.  Agr.  Research  IV,  pp.  129-133  (1915). 
(Cor.  Sub.)  Mich.  Agr.  Exp.  Sta.,  Bull.  108,  pp.  38-45  (1894). 
Ind.  Agr.  Exp.  Sta.,  Bull.  56,  pp.  70-80  (1895). 
Conn.  Agr.  Exp.  Sta.,  Rep.  19,  1895,  pp.  166-176  (1896). 

(Formalin)  U.  S.  Dep.  Agr.,  Farm.  Bull.  91,  pp.  9-10  (1899). 
Scurf  (Rliizoctonia  solani,  Kiihn  =  Coriicium  vagum,  B.  &  C,  var.  solani,  Burt.). 
Silver-scurf  (S pondylocladium  alrovircns,  Harz.). 

Orton,  U.  S.  Farm.  Bull.  544  (1913). 

Journ.  Agr.  Research  VI,  pp.  339-350  (June,  1916). 
Stem-blight  (Fusarium  acuminatum,  Ell.  &  Ev.  ?). 

Descr.,  N.  Y.  Agr.  Exp.  Sta.,  Bull.  loi,  p.  85  (1896). 

Cf.  N.  Y.  Agr.  Exp.  Sta.,  Bull.  138,  pp.  632-634  (1897). 
Stem-rot  {Coriicium  vagum,  Bri.  &  Cav.,  var.  solani,  Burt.). 

Cal.  Bull.  70,  pp.  1-20,  pis.  12  (March,  1902). 
Tuber-rot  {Fusarium  oxysporum,  Schlecht). 

Orton,  U.  S.  Farmer's  Bull.  544  (1913). 

Bull.,  U.  S.  Dep.  Agr.,  No.  64  (1914). 
Wart  {Synchytritim  endohioticiim  (Schilb.),  Percival). 

Orton,  W.  A.,  Potato  Tuber  Diseases,  U.  S.  Farmer's  Bull.  544  {igi^,). 
Wet-rot  {Bacterial). 

Descr.,  Del.  Agr.  Exp.  Sta.,  Rep.  4,  1891,  pp.  54-57  (1892). 
Wilt  {Bacillus  solanacearum,  E.  F.  Sm.). 
Yellow-blight  {Sclerotinia  liberliana,  Fckl.;  Syn.  Peziza  postuma,  Berk.  &  WUs.  ?). 

Primrose 
{Primula,  spp.) 
C  Phyllosticta  primulicola,  Desm. 


Miscellaneous  Fungous  Diseases. 


Ramularia  primulce,  Thm. 
CoUetolrichum  primulce,  Hals. 
[  Ascochyta  primula.  Trail. 
See  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  pp.  377-380  (1895). 


Privet 

{Ligustrum  vulgare,  L.) 

Anthracnose  {Glceosporium  cingulatum,  Atk.). 

Descr.  Illus.,  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  49,  PP-  306-314  (1892). 
Leaf-spot  {Cercospora  adusta,  Heald  &  Wolf,  C.  Hgustri,  Roum  and  Phyllosticta 
ovalifolia,  Brun.) 

Quince 
{Pirus  cydonia,  L.) 

Black-rot  {Sphosropsis  malorum.  Berk.). 

Descr.  Illus.,  N,  J.  Agr.  Exp.  Sta.,  Bull.  91,  pp.  8-10  (1892). 
Treat,  (rec),  Conn.  Agr.  Exp.  Sta.,  Bull.  115,  pp.  6-7  (1893). 


LIST   OF   SPECIFIC   DISEASES   OF   PLANTS  459 

Fire-blight  {Bacillus  amylovorus  (Burr.),  Trev.). 

See  Apple  and  Pear  (Fire-blight). 
Leaf-blight  {Entomosporium  maculatum,  Lev=Fabraea  maciihUum  (Lev.)  Atk. 

Descr.  lUus.,  See  Pear  (Leaf-spot). 

Treat,  (pos.),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  80,  pp.  619-625  (1894). 
Mold  {Sclerotinia  cydonice,  Schellenb.). 
Pale-rot  (Phoma  cydonia,  Sacc.  &  Schulz.?). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Bull.  91,  pp.  lo-ii  (1892). 
Ripe-rot  or  Anthracnose  {Glceosporiiim  fructigenum,  Berk.). 

See  Apple  and  Grape  (Ripe-rot). 
Rust  {Gymnosporangimn  clavipes,  C.  &  P.,  Syn.  Rcestelia  aurantiaca,  Pk.). 

Descr.^Illus.,  N.  J.  Agr.  Exp.  Sta.,  Bull.  91,  pp.  2-5  (1892). 

N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  80,  pp.  625-626  (1894). 
Mass.  Hatch  Rep.,  pp.  61-63  (1897). 

Treat,  (rec),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  80,  p.  627  (1894). 

Radish 
{Raphantis  sativus,  L.) 

Club-root  {Plasmodiophora  brassica;,  Wor.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  pp.  348-349  (1891). 
Downy  Mildew  (Peronospora  parasitica  (Pers.)  deBy.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  349  (1891). 
White-rust  {Cyslopus  candidus  (Pers.),  Lev.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  350  (1891). 

Treat,  (rec),  N.  J.  Agr.  E.xp.  Sta.,  Rep.  11,  1890,  p.  350  (1891). 

Raspberry 
(Rubus  spp.) 

Anthracnose  {Glceosporiiim  venclum,  Speg.  =  Gl.  necator,  Ell.  &  Ev.). 

Descr.  Illus.,  U.  S.  Dept.  Agr.,  Rep.  for  1887,  pp.  357-360  (1888). 
Ohio  Agr.  Exp.  Sta.,  Bull.  IV-6,  pp.  124-126  (1891). 
N.  Y.  Agr.  Exp.  Sta.,  Bull.  124,  pp.  262-264  (1897). 

Treat,  (pos.),  Conn.  Agr.  Exp.  Sta.,  Rep.  23,  '99,  pp.  274-276  (1900). 
Black-blight  {Fnsarium,  sp.  ?). 
Blue-stem  {Acrostolagmiis  caulophagus,  Lawrence.). 

Washington  Bull.  108,  pp.  30,  figs.  28  (October,  191 2). 
Cane-blight  {Coniothyrimn  Fuckelii,  Sacc). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  177  (1910). 

Descr.  N.  Y.  Agr.  Exp.  Sta.,  Bull.  107,  pp.  305-307  (1899). 
Crown-gall  (Possibly  identical  with  Crown-gall  of  Peach,  q.v.). 

See  Ohio  Agr.  Exp.  Sta.,  Bull.  79,  pp.  108-112  (1897). 
Fire-blight  (Bacterial). 

Descr.,  Ohio  Agr.  Exp.  Sta.,  Bull.  IV-6,  pp.  128-129  (1891). 


460  SPECIAL   PLANT    PATHOLOGY 

Leaf-spot  {Scploria  riihi,  Westd). 

Mushroom  Root- rot  (Armillaria  hirllca  Vahl). 

Ore.  Sta.  Bien.  Rep.  (1911-12). 
Orange-rust  {Gyntnoconia  interstitial  is). 

Bull.  212,  Colo.  Exp.  Sta.  (October,  1915). 
Rust  {Gymnoconia  intcrstltialis  (Schl.)  v.  Lagerh.). 
Spur-blight  {Spharclla  rubina  Pk.). 

Bull.  212,  Colo.  Exp.  Sta.  (October,  1915). 
Wilt  {Leptosphccria  coniothyriiini  (Fckl.)  Sacc). 

Red  Gum 

{Liqiiidamhar  styracljlua,  L.)' 

Sap-rot  {Polyslictus  versicolor,  (L.)  Fr.). 

von  Schrenk,  Diseases  of  Deciduous  Forest  Trees,  U.  S.  Bur.  Plant  Industry, 
Bull.  149  (1909). 

Red  Top 

(Agrostis  alba,  L.) 

Sclerotial  Disease  {Sclerotium  rhizodes,  Auersw.). 
Conn.  E.xp.  Sta.,  Rep.,  p.  23  (1914). 

Rice 

{Oryza  saliva,  L.) 

Blast  {Piricularia  oryza,  Cav.). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  352  (1910). 

Cook,  Diseases  of  Tropical  Plants,  p.  99  (1913). 
Smut  (Tilletia  corona,  Scrib.). 

Descr.  Illus.,  S.  Car.  Agr.  Exp.  Sta.,  Bull.  41,  pp.  7-1 1  (1899). 

Treat,  (rec.;,  S.  Car.  Agr.  Exp.  Sta.,  Bull.  41,  pp.  15-29  (1899). 

Rose 
{Rosa  spp.) 

Anthra'cnose  {Glososporium  rosce,  Hals.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  pp.  401-405  (1894). 
Cane-blight  {Coniothyrium  Fuckelii  Sacc). 
Downy  Mildew  {Peronospora  sparsa,  Berk.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  13,  1892,  p.  282  (1893). 

'von  Schrenk,  Hermann:  Sap-rot  and  other  Diseases  of  the  Red  Gum,  U. 
S.  Bureau  of  Plant  Industry,  Bull.  114,  1907,  where  all  the  important  diseases 
are  considered. 


LIST   OF    SPECIFIC   DISEASES    OF   PLANTS  46 1 

Leaf-blotch  {Actinonema  rosa  (Lib.),  Fr.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  pp.  366-368  (1888). 

Treat,  (pos.),  N.  J.  Agr.  Exp.  Sta.,  Rep.  13,  1892,  p.  281  (1893). 
Leaf-spot  {Splitrrella  rosigena,  EIL). 

Occ. 
Mildew  {Peronospora  sparsa,  Berk.). 
Powdery  Mildew  {Sphcerotheca  pannosa  (Wallr.),  Lev.). 

Descr.,  N.  J.  Agr.  E.xp.  Sta.,  Rep.  13,  1892,  p.  281  (1893). 

Treat,  (pos.),  N.  J.  Agr.  E.xp.  Sta.,  Rep.  13,  1892,  pp.  281-282  (1893). 
Rust  {Phragmidium  subcortkium  (Schrank)  Wint.  and  P/k  speclomm,  Fr.). 

Descr.  Illus.,  U.  S.  Dept.  Agr.,  Rep.  for  1887,  pp.  369-372  (1888). 

Treat,  (pos.),  See  U.  S.  Dept.  Agr.,  Exp.  Sta.  Rec,  X-7,  p.  651  (1899). 
Twig-blight  {Botrylis  clnerea,  Pers.). 

Rye 

{Secalc  ccrcale,  L.) 

Anthracnose  (Collciotrichum  gramincola  (Ces.)  Wilson). 
Ergot  (Claviceps  purpurea,  (Fr.)  TuL). 

Descr.  Illus.,  S.  Dak.  Agr.  Exp.  Sta.,  Bull.  33,  pp.  40-43  (1893). 

Treat,  (rec),  N.  C.  Agr.  Exp.  Sta.,  Bull.  76,  p.  20  (1891). 
Rust  (Black-stem,  Puccinia  graminis,  Pers.,  and  Orange-leaf,  P.  rubigO'vera  (DC), 
Wint.). 

See  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  16,  pp.  42-45  &  60. 
Smut  {Urocystis  occulta  (Wallr.),  Rabh.). 

Occ.  Illus.,  Mass.  Agr.  E.xp.  Sta.,  Rep.  9,  1891,  p.  247  (1892). 

Treat,  (pos.),  see  Oats  and  Wheat  (Smut). 
Stem-blight  {Leptosphceria  herpotrichoidcs,  de  Not). 

Salsify 

{Tragopogon  porrifoliits,  L.) 
Rot  (Bacterial). 

Descr.,  N.  J.  Agr.  E.xp.  Sta.,  Rep.  11,  1S90,  p.  351  (1891). 
White-rust  {Cystopus  iragopogonis,  (Pers.),  Schrot.). 

Occ,  N.  J.  Agr.  E.Kp.  Sta.,  Rep.  15,  1894,  p.  355  (1895). 
Rust  {Puccinia  tragopogoni  (Pers.),  Cda.). 

Scrub  Pine 
{Pinus  virigitiiana,  Mill) 

Burl  Disease  {Cronarlium  quercus  (Brand.)  Schrot). 

Graves,  A.  H.,  Phytopathology  IV  (February,  1914). 
Heart-rot  {Trameles  pint  (Brot.)  Fr.). 

Graves,  A.  H.,  Phytopathology  IV  (February,  1914). 


462  SPECIAL  PLANT  PATHOLOGY 

Leaf-cast  {Galloivaya  pini  (Gall.),  Arth.). 

Graves,  A.  H.,  Phytopathology  IV  (February,  1914). 
Rust  (Coleosporium  inconspicuum  (Long),  Hedg.). 

Graves,  A.  H.,  Phytopathology  IV  (February,  1914). 

Shaddock  or  GRAPE-FRtni 
{Citrus  decumana,  Murr.) 
See  Lemon  and  Orange 

Snapdragon 
{Antirrhinum  niajiis,  L.) 
Anthracnose  {Colletotrichum  antirrhini,  Stewart). 

Descr.  Illus.  Treat,  (pos.),  N.  Y.  Agr.  Exp.  Sta.,  Bull.  179  (1900). 
Root-rot  {Thielavia  basicola,  Zopf.). 
Rust  {Puccinia  antirrhini,  Diet.  &  Holway.). 
Stem-rot  {Phoma  sp.). 

Descr.  Treat,  (rec),  N.  Y.  Agr.  Exp.  Sta.,  Bull.  179,  pp.  109-110  (1900). 

Sorghum 
{Sorghum  vulgare,  Pers.) 

Blight  {Bacillus  sorghi,  Burrill). 

Descr.,  Kan.  Agr.  Exp.  Sta.,  Rep.  i,  1888,  pp.  281-301  (1889). 

Treat,  (rec),  Kan.  Agr.  Exp.  Sta.,  Rep.  i,  1888,  pp.  301-302  (1889). 
Head-smut  {Sorosporlum  reilianum  (Kiihn)  McAlpine). 

Journ.  of  Agr.  Research  II,  pp.  340-371  (Aug.  15,  1914). 

Descr.  Illus.,  Kan.  Agr.  Exp.  Sta.,  Bull.  23,  pp.  95-96  (1891). 
111.  Agr.  Exp.  Sta.,  Bull.  47,  pp.  374-388  (1897). 
111.  Agr.  Exp.  Sta.,  Bull.  57,  pp.  335-347  (1900)- 

Treat,  (pos.),  111.  Agr.  Exp.  Sta.,  Bull.  57,  pp.  345-346  (1900). 
Kernel-smut  {S phacelotheca  sorghi). 

BuU.  212,  Colo.  Agr.  Exp.  Sta.  (October,  1915). 

Journ.  Agr.  Research  II,  pp.  339-371,  pis.  7  (1914). 

Soy 
{Soja  hispida,  Moench.) 

Wilt-disease  {Fusarium  tracheiphilum,  E.  F.  Sm.),  Journ.  Agric.  Res.  8:  421-439, 
with  I  pi.,  Mch.  12,  191 7. 

Spinach 
{Spinacia  oleracea,  Mill.) 

Leaf-blight  {Cercospora  beticola,  Sacc). 

Descr.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  355  (1891). 
Cf.  N.  J.  Agr.  Exp.  Sta.,  Rep.  18,  1897,  p.  303  (1898). 


LIST   OF   SPECIFIC  DISEASES   OF   PLANTS  463 


Miscellaneous 
Fungous  Diseases. 


Anthracnose  {CoUetotrichum  spinacecs,  Ell.  &  Hals.). 

Downy  MUdew  {Peronospora  effiisa,  (Grev.),  Rabenh.). 

Leaf-spot  {Phyllostida  chenopodii,  Sacc.)." 

Scab  {Cladosporium  inacrocarpum,  Preuss). 
^  White  Smut  (Entyloma  Ellisii,  Hals.)  . 
Descr.  Illus.,  N.  J.  Agr.'  Exp.  Sta.,  Bull.  70  (1890). 
Treat,  (rec),  N.  J.  Agr.  Exp.  Sta.,  Bull.  70,  pp.  13-14  (1890). 

Spruce 

{Picea  spp.)i 

Blight  of  Seedlings  (Ascochyta  piniperda,  Lindsin  =  Dlplodina  parasitica  (Hart,  Prill), 
and  Sderotinia  Fuckeliana,  deBy). 
Graves,  A.  H.,  Phytopathology  IV  (April,  1914). 
Brown-rot  {Polyporus  sulphureus  (Bull.)  Fr.). 
Dry-rot  (Trametes  pini  (Brot.)  Fr.  and  T.  abietis 

Karst.). 
Heart- rot  {Polyporus  borealis  (Wahl.)  Fr.). 

Atkinson,  BuU.  193  (Corn.  Univ.)  Agr.  Exp.  Sta. 
(June,  1901). 
Root-rot  {Polyporus  Schweinitzii,  Fr.). 
Wet-rot  {Polyporus  suhacidus,  Pk.  ?). 


Descr.  Illus.,  U.  S.  Dep.  Agr. 
Div.  Veg.  Phys.  &  Path. 
Bull.  25  (1900). 


Squash 

{Cucurbit a  spp.) 

Anthracnose  {CoUetotrichum  lagenarium  (Pass.),  Ell.  &  Hals.). 

Bacteriosis  or  Wilt  {Bacillus  tracheiphilus,  E.  F.  Sm.). 

Downy  Mildew  {Plasmopara  cubensis  (Bri.  &  Cav.),  Humph.). 

Fruit-mold  {Macrosporium  sp.). 

Powdery  MUdew  {Erysiphe  cichoracearum,  DC.  and  E.  polygoni,  DC). 

Descr.  Illus.,  See  Cucumber  (Powdery  Mildew). 

Treat,  (pos.),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  35,  p.  330  (1891). 
Leaf-spot  {Cercospora  cucurbitce,  Ell.  &  Ev.). 

Strawberry 

{Fragaria  spp.) 
Blight  {Micrococcus  sp.  ?). 

Descr.,  Mass.  Agr.  Exp.  Sta.,  Rep.  9,  1896,  pp.  59-61  (1897). 
Leaf-blotch  {Ascochyta  fragaria,  Sacc). 

Descr.  Illus.,  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  14,  pp.  182-183  (1889). 
Treat,  (rec),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  BuU.  14,  p.  183  (1889). 
^  For  species  of  Peridermium  on  spruce  consult  Arthur  &  Kern,  North  American 
Species  of  Peridermium,  Bull.  Torr.  Bot.  Club  2>2„  PP-  403-438,  1906. 


464  SPECIAL   PLANT   PATHOLOGY 

Leaf-spot  {Aposphceria  sp.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  pp.  329-330  (1894). 

Treat,  (rec.)  N.  J.  Agr.  Exp.  Sta.,  Rep.  14,  1893,  pp.  331-332  (1894)- 
Leaf-spot  {Mycosphcerclla  fragarice,  (Tul.)  Lindau). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1887,  pp.  334-339  (1888). 

N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  14,  pp.  171-181  (iJ 
Oregon  State  Biennial  Rep.    p.  268  (1911-12). 
Leaf-spot  {Mycos phcerella  fragarice  (Tul.),  Lindau). 

Treat,  (pos.),  U.  S.  Dep.  Agr.,  Rep.  for  1890,  p.  397  (1890). 
Conn.  Agr.  Exp.  Sta.,  Bull.  115,  p.  14  (1893). 
Powdery  Mildew  (Sphcerotheca  Castagnei,  Lev.). 

Descr.,  N.  Y.  Agr.  E.xp.  Sta.,  Rep.  5,  1886,  pp.  291-292  (1887). 

Descr.  Illus.,  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  p.  239  (1893). 

Treat,  (rec),  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  pp.  243-245  (1893). 
Rot  (Sphceroncemella  fragarice,  Stev.  &  Pet.). 

Phytopath.  VI,  pp.  258-266  (1916). 

Sugar-C.4ne1 

{Saccliarum  officinarum,  L.) 

Bundle-blight  {Pseudomonas  vascularum  (Cobb.)  E.  F.  Sm,). 
Cacao  Disease  (Diplodia  cacaoicola,  Henn). 

Cook,  Disease  of  Tropical  Plants,  p.  85  (1913). 
Iliau  {Gnomonia  iliau,  Lyon). 

Cook,  p.  85  (1913)- 

Phytopath.  3,  pp.  93-98  (191 3). 
Leaf-spot  {Ccrcospora  longipes,  Butler). 

Cook,  p.  89  (1913). 

Macrosporium  gramimim,  Cke. 


Miscellaneous  Diseases.     1   ,,.  ^^..,    ..  ,„  ..    ^    ,^7  1  1     o   -ht     ^ 

Uromyces  Kuhnii  (Krug.j,  Wakk.  &  Went. 

Pineapple  Disease  {Thielaviopsis  ethacelicus,  Went). 

Red- rot  {Collelotrichum  falcatum,  Went). 

Rind  Disease  {Trichosphceria  sacchari,  Mass.). 

See  U!  S.  Dept.  Agr.,  Exp.  Sta.  Rec,  X,  pp.  56-57,  '98,  and  XI,  p.  759  (1900). 
Ring-spot  {Leptosphceria  sacchari,  de  Haan) . 

Cook,  p.  89  (1913). 
Smut  {Ustilago  sacchari,  Rabenh.). 
Stool  Disease  (Marasmius  sacchari,  Wakker). 

Cook,  p.  92  (1913). 

1  Cf.  Edgerton,  C.  W.:  Some  Sugar-cane  Diseases,  Bull.  120,  La.  Agric.  Exper. 
Sta.,  July,  1910;  Cobb,  N.  A.:  Fungous  Maladies  of  the  Sugar  Cane,  Bull.  6,  Exper. 
Sta.,  Hawaiian  Sugar  Planters  Assoc,  1906. 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  465 

Sunflower 
(Helianthtis  anntius,  L.) 

Black-rot  {SphcBronema  fimbriatum  (Ell.  &  Hals.)  Sacc). 

Duggar,  p.  348  (1909). 
Dry-rot  (Phoma  batata,  Ell.  &  Hals.). 

Duggar,  p.  344  (1909). 
Root-rot  {Cortkium  vagum,  B.  &  C.  var.  solani,  Burt.). 

Duggar,  p.  444  (1909). 
Rust  (Puccinia  lielianiki,  Schw.). 

Sweet  Pea 
{Lathyrus  odoratus,  'L.y 

Anthracnose  {Glomcrella  rufomacidans  (Berk.),  Spauld.  &  v.  Schr.). 

Powdery  Mildew  (Erysiphe  polygoni  DC). 

Root-rot   (Thielavia  basicola,    Zopf.;   Rhizoctonia   {Corticium  vagum,   Bri.  &   Cav. 

var.   solani  Burt);   ChcBlomiiim  spirochete,  Pall.;  Fusarium  lathyri,  Taub. 

&  Manns). 
Stem  or  Collar-rot  {Sclerotinia  libertiana,  Fckl.). 
Streak  {Bacillus  lathyrii,  Manns  &  Taub.). 

Sweet  Potato 
{Ipomceo  batatas,  Lam.) 

Black-rot  (Sphoeronema  (Ceratocystis)  fimbriata  (Ell.  &  Hals.),  Sacc). 
Descr.  Illus.,  N.  Y.  Agr.  Exp.  Sta.,  Bull.  76,  pp.  7-13  (1890). 

Journ.  Mycol.,  Vol.  VII,  pp.  1-9  (1891). 
Treat,  (pos.),  Md.  Bull.  60,  pp.  147-168,  figs.  17  (March,  1899). 
(rec),  U.  S.  Dept.  Agr.,  Farm.  Bull.  26,  p.  21  (1895). 
Charcoal-rot  {Sclcrollum  bataticola,  Taub.). 

Phytopathology  3,  p.  161  (1913). 
Foot- rot  (Plenodomus  destruens.  Hart.). 

Phytopathology.     3,  pp.  242-245  (1913). 

Taubenhaus  &  Manns,  Bull.  109,  Del.  Agr.  Exp.  Sta.,  May,  1915. 
Journ.  Agr.  Research  I,  p.  251 
Java- rot  {Las iodiplodia  tuber icola,  Ell.  &  Ev.). 
Soil-rot  {Acrocystis  batatae,  Ell.  &  Hals.). 

Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Bull.  76,  pp.  14-18  (1890). 
Treat,  (pos.),  N.  J.  Agr.  Exp.  Sta.,  Rep.  20,  1899,  pp.  345-354. 

N.  J.  Spec.  Bull.  5,  February,  1900,  pp.  22-31,  pis.  3  (1900). 

1  Consult  Taxjbenhaus,  J.  J.:  The  Diseases  of  the  Sweet  Pea,  Bull.  106,  Del. 
Agric.  Exper.  Sta.,  November,  1914. 
30 


466  SPECIAL  PLANT   PATHOLOGY 

Stem-wt  {Fusanum  hyperoxysporum  Wollenw.). 
U.  S.  Farmers'  Bull.  714,  March  11,  1916. 
Phytopath.  4,  pp.  277-303  (1914). 

Dry-rot  {Phoma  batatce,  Ell.  &   Hals,  conidial  stage  of  Diaporlhe 

batatatis  (Ell.  &  Hals.),  Hart  &  Field). 
Leaf-spot  {Phyllosticla  bataticola,  Ell.  &  Mart.) . 

U.  S.  Farmers'  Bull.  711. 
Scurf  {Monilochates  infuscans  (Ell.  &  Hals.)  Hart). 
Miscellaneous  N.  J.  Bull.  76,  pp.  25-27  (Nov.,  1890). 

Diseases.         |  Soft-rot  {Rhizopus  nigricans,  Ehrb.). 
Phytopath.  4,  pp.  305-320. 
Trichoderma  Rot  (Trickoderma  Koningi,  Oud.). 

Taubenhaus  &  Manns,  Bull.  109,  Del.  Agr.  Exp.  Sta.,  May, 
1915- 
White-rot  {Penicillium  sp.). 

White-rust  {Cystopus  ipomaos-pandurance  (Schw.),  Farl.). 
Descr.  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Bull.  76  (1890). 
Md.  Agr.  Exp.  Sta.,  Bull.  60  (1899). 
Treat,  (rec),  U.  S.  Dept.  Agr.,  Farm.  Bull.  26  (1895). 
Vine- wilt  {Fusarium  batatatis,  Wollenw.). 

Taubenhaus  and  Manns,  Bull.  109,  Del.  Agr.  Exp.  Sta.,  May,  1915. 
Wollenweber,  H.  W.,  Journ.  Agr.  Research  2,  pp.  251-283  (191 1). 

Sycamore 

(Platanus  occidentalis,  L.) 

Anthracnose   {Glceosporinm  nervisequum   (Fckl.),  Sacc,  stage  of  Gnomonia  veneta 

(Sacc.  &  Speg.)  Kleb.). 
Blight  {Gnomonia  veneta  (Sacc.  &  Speg.),  Kleb.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  387-389  (1889), 
Treat,  (rec),  U.  S.  Dep.  Agr.,  Rep.  for  1888,  p.  389  (1889). 
Cf.  Journ.  Mycol.,  Vol.  V,  pp.  51-52. 
Gar.  and  For.,  X-488,  pp.  257-258. 

Tea 

{Thea  chinensisY 

Bark  Disease  (Corticium  javanicum,  Zimm.  =  C  Zimmermani,  Sacc.  &  Syd,). 

Blister- blight  {Exobasidium  vexans,  Massee.). 

Copper-blight  {Loestadia  tliece,  Show). 

Grey- blight  (Pestalozzia  guepini,  Desm.). 

Horsehair-blight  (Marasmius  sarmentosus.  Berk.). 

Internal  Stem  Disease  {Massaria  theicola,  Petch.). 

Red-rust  {Cephaleus  mycoidea,  Karst.). 

1  For  all  consult  Cook,  Diseases  of  Tropical  Plants,  pp.  170-180  (1913). 


LIST   OF    SPECIFIC   DISEASES   OF   PLANTS  467 

Root  Fungus  {Roscllinia  radicipcrda,  Massee.)- 
Soot- blight  (Capnodium  Footii  Berk,  and  Desm.). 
Thread- blight  (Stilbum  nanum,  Massee.). 

Teosinte 
{Euchlcena  mexicana,  Schrod.) 
Smut  {Ustilago  zeoe  (Beckm.),  Ung.). 

Timber 

Decay  (Stereum  fmstulosum  (Pers.),  Fr.). 

von  Schrenk,  Diseases  of  Deciduous  Forest  Trees,  U.  S.  Bureau  of  Plant  Industry, 
Bull.  149  (1909). 
Sap-rot  {Dadalea  quercina  (L.),  Pers.)- 

Mainly  on  oak  timber,  von  Schrenk  (1909). 

Timothy 
{Phleum  pratense,  L.) 

Ergot  {Claviceps  purpurea  (Fr.),  Tul.). 

Phytopath.  4,  pp.  20-22  (1914). 
Rust  {Puccinia  phlei-pratensis,  Eriks  &  Henn.) 

Phytopath.  4,  pp.  20-22  (1914). 
Smut  {Ustilago  stricef omits  (West.),  Niessl.). 

Tobacco 
{Nicoliana  labacum,  L.) 

Black- rot  {Sterigmatocystis  nigra  v.  Tieg.) . 

Wise.  Res.  Bull.  32,  pp.  63-83,  figs.  7  (June,  1914). 
Blue  Mold  {Fungus  indet.).    . 
Brown-spot  {Macros poritim  longipes,  Ell.  &  Ev.) 

Descr.,  Journ.  Mycol.,  Vol.  VII,  p.  134  (1892). 

Cf.  U.  S.  Dept.  Agr.,  Exp.  Sta.  Rec,  XII-4,  p.  359  (1900). 
"Damping-o2"  {Altertiaria  tenuis,  Nees). 

Downy  Mildew  |  J^f'^^f f '^  hyoscyami,  deBy.). 

1^  {Phytophthora  nicottanoe,  de  Haan). 
Leaf-blight  {Cercospora  nicotianoe,  Ell.  &  Ev.). 

Descr.  Illus.,  Conn.  Agr.  E.xp.  Sta.,  Rep.  20,  1896,  pp.  273-277  (1897). 

Treat,  (rec),  Conn.  Agr.  Exp.  Sta.,  Rep.  20,  1896,  pp.  277-278  (1897). 

Mosaic,  Bull.  U.  S.  Dept.  Agr.,  p.  40  (1914). 


468  SPECIAL  PLANT   PATHOLOGY 

Pole-burn  (Fungi  and  Bacteria). 

Descr.,  Conn.  Agr.  Exp.  Sta.,  Rep.  15,  1891,  pp.  168-173  (1892). 

Descr.,  Conn.  Agr.  Exp.  Sta.,  Rep.  17,  1893,  pp.  84-85  (1894). 

Treat,  (rec),  Conn.  Agr.  Exp.  Sta.,  Rep.  15,  1891,  pp.  180-184  (1892). 
Powdery  Mildew  {Erysiphe  cichoracearum,  DC,  Syn.  E.  lamprocarpa  (Wallr.),  Lev.). 
Root-rot  {Thielavia  basicola,  Zopf.). 

Gilbert,  W.  W.,  Bull.  158,  U.  S.  Bur.  of  Plant  Industry  (1909). 
Conn.  Rep.,  pt.  5,  p.  342   (1906.) 

Phytopath.  6,  pp.  167-181  (,1916). 
Stem-rot  (Botrylis  longihradiiata,  Oud.) . 

Cook,  Diseases  of  Tropical  Plants,  p.  149  (191 3). 

Descr.,  Conn.  Agr.  Exp.  Sta.,  Rep.  15,  1891,  pp.  184-185  (1892). 

Treat,  (rec).  Conn.  Agr.  Exp.  Sta.,  Rep.  15,  1891,  pp.  185-186  (1892). 
White-speck  {Macros porium  tabacinum,  Ell.  &  Ev.). 

Descr.,  Journ.  Mycol.,  Vol.  VII,  p.  134  (1892). 

Cf.  Conn.  Agr.  Exp.  Sta.,  Rep.  20,  1896,  p.  276  (1897). 

Tomato 
{Lycopersicum  esculentum,  Mill.) 

Anthracnose  {Collctotrichum  phomoides  (Sacc),  Chester). 

Descr.  Illus.,  Del.  Agr.  Exp.  Sta.,  Rep.  4,  1891,  pp.  60-62  (1892). 

Cf.  Del.  Agr.  Exp.  Sta.,  Rep.  6,  1893,  pp.  111-115  (1894). 

Nebr.  Rep.,  1907,  pp.  1-33,  figs.  S3- 

Treat,  (rec),  Me.  Agr.  Exp.  Sta.,  Rep.  for  1893,  p.  155  (1894). 
Blight  {Pscudomonas  solanacearum,  E.  F.  Sm.). 

Descr.  Illus.,  See  Egg-plant  (Blight). 

La.  BuU.  142,    pp.  1-23,  figs.  3   (October,  1913). 

Treat,  (pos.),  Md.  Agr.  Exp.  Sta.,  Bull.  54,  pp.  123-125  (1898). 
Fla.  Agr.  Exp.  Sta.,  Bull.  47,  pp.  133-136  (1898). 
Blight  {Sclerotium  sp.). 

Descr.,  Fla.  Agr.  Exp.  Sta.,  Bull.  21,  pp.  25-27  (1893). 
Ala.  Agr.  Exp.  Sta.,  Bull.  108,  pp.  28-29  (iQoo)- 

Treat,  (pos.),  Fla.  Agr.  Exp.  Sta.,  Bull.  21,  pp.  32-36  (1893). 
Downy  Mildew  {Pliyloptliora  infestans  (Mont.),  deBy.). 

Fruit-rot  {Macrosporium  solani,  E.  «fe  M.  and  Phoma  dcstructiva,  (Plowr.), 
Jamies.) 

Descr.,  Ala.  Agr.  Exp.  Sta.,  Bull.  108,  pp.  19-25  (1900). 

Cf.  N.  Y.  Agr.  Exp.  Sta.,  Rep.  3,  1884,  pp.  379-380.     1885. 

Cf.  N.  Y.  Agr.  Exp.  Sta.,  Bull.  125,  pp.  305-306.     1897. 

Journ.  Agr.  Research  4,  p.  i  (April  15,  1915)- 
Leaf-blight  {Cylindros porium  sp.) . 

Descr.,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  14,  1895,  p.  529  (1896). 

Treat,  (rec),  N.  Y.  Agr.  E.xp.  Sta.,  Rep.  14,  1895,  pp.  530-531  (1896). 
Leaf-mold  {AUernaria  solani  (Ell.  &  Mart.),  Jones  &  Grout).  , 


LIST    OF    SPECIFIC   DISEASES    OF   PLANTS  469 

Descr.,  Fla.  Agr.  Exp.  Sta.,  Bull.  47,  pp.  124-125  (1898). 
Treat,  (pos.-),  Fla.  Agr.  E.xp.  Sta.,  Bull.  47,  pp.  125-127  (1898). 
Leaf-spot  {Septoria  lycopersici,  Speg.). 

Descr.  Illus.,  Del.  Agr.  Exp.  Sta.,  Rep.  7,  1894-95,  p.  123  (1895). 

Ohio  Agr.  Exp.  Sta.,  Bull.  73,  p.  241  (1897). 
Treat,  (pos.),  Va.  Bull.  192,    pp.  16,  figs.  9  (April,  191 1). 

Ala.  Agr.  Exp.  Sta.,  Bull.  108,  pp.  32-33  (1900). 
Rust  (Macrosporium  solani,  Ell.  &  Mart.). 

Stevens  &  Hall,  Diseases  of  Economic  Plants,  p.  312  (1910). 
Scab  (Cladosporium  fulvum,  Cke.). 

Descr.  Illus.,  U.  S.  Dep.  Agr.,  Rep.  for  1888,  pp.  347-348  (1889). 
Treat,  (pos.),  U.  S.  Dep.  Agr.,  Sec.  Veg.  Path.,  Bull.  11,  p.  47  (1890). 
Ala.  Agr.  Exp.  Sta.,  Bull.  108,  p.  ^^  (1900). 
Wilt  {Fusarium  lycopersici,  Sacc). 

Trumpet  Creeper 
(Tecoma  radicans  (L.)  Jass.) 

Leaf-blight  (Cercospora  sordida,  Sacc.) .  '      . 

Duggar,  p.  315  (1909). 
Leaf-spot  {Septoria  lecomce,  Ell.  &  Ev.). 

Tulip  Tree 
{Liriodendron  tulipifcra,  L.) 

Leaf -blight  {Glceosporium  liriodendri,  Ell.  &  Ev.). 
Sap-rot  {Pclyst ictus  versicolor  (L.),  Fr.). 

von  Schrenk,  H.,  Diseases  of  Deciduous  Forest  Trees,  U.  S.  Bur.  of  Plant  In- 
dustry, Bull.  149  (1909). 

Turnip 

{Brassica  campcstris,  L.  and  B.  rapa,  Linn.) 

Brown-rot  (Fseudomonas  campestris  (Pam.),  E.  F.  Sm.). 

Descr.  Illus.,  Iowa  Agr.  Exp.  Sta.,  Bull.  27,  pp.  130-134  (1895). 
Club-root  (Plasmodiophora  brassicce,  Wor.). 

Descr.  Illus.,- See  Cabbage  (Club-root). 

Treat,  (pos.),  N.  J.  Agr.  Exp.  Sta.,  Rep.  20,  '99,  pp.  354-367  (1900). 
Downy  MUdew  {Peronospora  parasitica  (Pers.)  deBy.). 

Occ,  Mass.  Agr.  Exp.  Sta.,  Rep.  8,  1890,  p.  222  (1891). 

Treat,  (rec),  Mass.  Agr.  Exp.  Sta.,  Rep.  8,  1890,  p.  223  (1891). 
Dry-rot  (Plioma  brassicce,  Thiim  ?). 

See  U.  S.  Dept.  Agr.,  E.xp.  Sta.  Rec,  XII-3,  p.  256  (1900). 

Conn.  Exp.  Sta.,  Rep.,  p.  355  (191 2). 


470  SPECIAL   PLANT   PATHOLOGY 

Leaf- mold  {Macros porium  herculeum,  E.  &  M.). 

Descr.  Illus.,  N.  Y.  Agr.  Exp.  Sta.,  Rep.  15,  '96,  pp.  451-452  (1897). 
Powdery  Mildew  (Erysiphe  polygoni,  DC). 

Occ,  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  61,  pp.  305-306  (1893). 
White-rust  (Cystopus  candidns,  (Pers.)  Lev.). 

Occ,  Mass.  Agr.  Exp.  Sta.,  Rep.  8,  i8go,  p.  222  (1891). 

Treat,  (rec),  Mass.  Agr.  Exp.  Sta.,  Rep.  8,  1890,  p.  223  (1891). 

Tree  of  Heaven 
{Ailanthus  glandulosa,  Desf.) 
Shot- hole  (Ccrcospora  glandiilosa,  Ell.  &  Kell.). 

Verbena 

{Verbena  sp.) 

Powdery  Mildew  {Erysiphe  cichoraccarum,  DC). 

Occ,  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  37,  p.  405  (1891). 

Treat,  (pos.),  N.  Y.  (Corn.  Univ.)  Agr.  Exp.  Sta.,  Bull.  37,  p.  405  (1891). 

Vetch 
( Vicia  spp.) 

Powdery  Mildew  {Erysiphe  polygoni,  DC). 

Duggar,  p.  227  (1909). 
Rust  {Uromyces  pisi  (Pers.)  de  By). 

Duggar,  p.  398  (1909). 

Violet    . 

{Viola  odorata,  L.  and  V.  tricolor,  L.) 

Anthracnose  {Glceosporinm  violce,  B.  &  Br.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  362  (1891). 
Anthracnose  {Colletotrichum  violce-iricoloris,  Smith). 

Descr.,  Mass.  Agr.  Exp.  Sta.,  Rep.  11,  '98,  pp.  152-153  (1899). 

Treat,  (pos.),  Mass.  Agr.  Exp.  Sta.,  Rep.  11,  '98,  p.  153  (1899). 
Gall  or  Chytridiose  {Cladochylrium  violce,  Berl.). 

See  U.  S.  Dep.  Agr.,  Exp.  Sta.  Rec,  XI-3,  p.  261  (1899). 
Downy  Mildew  {Peronospora  violas,  de  By.) . 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  362  (1891). 
Dry-rot  {Merulius  lacrymans  (Jacq.)  Fr.) . 

See  U.  S.  Dep.  Agr.,  Exp.  Sta.  Rec,  XI-io,  p.  947  (1900). 
Leaf-bhght  {Cercospora  violce,  Sacc). 

Occ  Illus.,  N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  pp.  3S4-386  (1895). 

Treat,  (rec)   N.  J.  Agr.  Exp.  Sta.,  Rep.  15,  1894,  pp.  386-389  (1895). 


LIST   OF    SPECIFIC    DISEASES    OF   PLANTS  47 1 

Leaf-mold  or  Spot  Disease  {AUernaria  violcc,  GaH.  &  Dors.). 

Descr.  Illus.  Treat.,  U.  S.  Dep.  Agr.,  Div.  Veg.  Phys.  &  Path.,  BulL  23  (1900). 
Leaf-spot  {Phylloslida  viola;,  Desm.  and  AUernaria  viola;,  GaU.  &  Dors.). 

Descr.,  Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  pp.  231-232  (1893). 

Treat,  (rec.)   Mass.  Agr.  Exp.  Sta.,  Rep.  10,  1892,  pp.  232-235  (1893). 
N.  J.  Agr.  Exp.  Sta.   Rep.  15,  1894,  pp.  286-389  (1895). 
Root-rot  (Tkielavia  basicola,  Zopf). 

Descr.  Conn.  Agr.  Exp.  Sta.,  Rep.  15,  1891,  pp.  166-167  (1892). 
White  Mold  (Zygodcsmus  albidiis,  Ell.  &  Hals.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  11,  1890,  p.  362  (1891). 

Virginia  Creeper 

(Ampelopsis  quinquefolia,  Michx.) 

Leaf-spot  {Phylloslida  ampdopsidis,  E.  &  M.)   =Laestadia  Bidwellii  (Ell.).  V.  &  R. 

Walnut 

(Juglans  regia,  L.) 

Bacteriosis    {Pseudomonas  jnglandis,  Pierce). 
Ore.  Sta.  Rep.,  p.  260  (1911-12). 

See  U.  S.  Dep.  Agr.,  Exp.  Sta.  Rec,  Vol.  XI,  p.  261  (1899). 
Cal.  Bull.  231,  pp.  320-383,  figs.  19  (August,  191 2). 
Leaf-blight  {Marsonia  juglandis  (Lib.)  Sacc.  oi  Gnomonia  leptosiyla  (Fr.)  Ces.  &  deN. 
Leaf-spot  {Ascochyta  juglandis,  Boltsh.  and  Phleospora  muUimaculans,  Heald  & 

Wolf.). 
Leaf  Disease  (Cylindrosporium  juglandis,  Wolf.) 
Mycologisches  Centralblatt  4,  p.  65  (1914). 

Watermelon  ; . 

(Cilrullus  vulgaris,  Schrad.) 

Anthracnose  (Colletotrichum  lagenarimn  (Pass.),  Ell.  &  Hals.). 

Occ,  N.  J.  Agr.  Exp.  Sta.,  Rep.  13,  1892,  p.  326  (1893). 

Treat,  (neg.),  Del.  Agr.  Exp.  Sta.,  Rep.  5,  1892,  p.  79  (1893). 

Cf.  N.  J.  Agr.  Exp.  Sta.,  Rep.  13,  pp.  326-330  (1892). 
Del.  Agr.  Exp.  Sta.,  Rep.  5,  pp.  75-79  (1892). 
Downy  MUdew  (Plasmopara  cubensis   (Bri.  &  Cav.),  Humph.). 

See  Cucumber  (Downy  Mildew). 
Leaf-blight  (Cercospora  citrullina,  Cke.). 

Occ,  Ohio  Agr.  Exp.  Sta.,  Bull.  105,  p.  232  (1899). 
Leaf-mold  (AUernaria  brassica,  Sacc,  var.  nigrescens,  Regel.). 

See  Melon  (Leaf-mold). 
Leaf-spot  {Phyllosticta  sp.  and  (?)  Spharella  sp.). 

Descr.  Ulus.,  DeL  Agr.  Exp.  Sta.,  Rep.  5,  1892,  pp.  75-78  (1893). 


472  SPECIAL   PLANT   PATHOLOGY 

Wheat 

{Trilicum  viilgare,  L.) 

Blight  (Mysirosporium  abrodens,  Neum.). 
Chytridiose  {Pyroctontim  spharicum,  Prunet). 

See  U.  S.  Dept.  Agr.,  Exp.  Sta.  Rec,  VI-3,  pp.  226-227  (1894). 
Ergot  (Claviceps  purpurea,  (Ft.)  Tul.). 

See  Rye  (Ergot). 
Foot-rot  [Ophlobolus  &  Leptospharia). 

See  U.  S.  Dept  Agr.,  Exp.  Sta.  Rec,  IX-ii,  p.  1057  (1898). 
U.  S.  Dept.  Agr.,  Exp.  Sta.  Rec,  X-7,  p.  650  (1899). 
Leaf-spot  {LeptosphcBria  eustoma  (Fr.),  Sacc,  var.  tritici,  Garov.). 
Leaf-spot  (Seploria  graminum,  Desm.). 

See  U.  S.  Dept.  Agr.,  Exp.  Sta.  Rec,  X-s,  p.  452  (1899). 
Mildew  {Erysiphe  graminis,  DC). 

Iowa  Bull.  104,  pp.  245-248  (July,  1909). 
Mold  (Cladosporiutn  hcrbarum  (Pers.),  Lk.). 

Rust  (Black-stem,  Puccinia  graminis,  Pers.  and  Orange-leaf,  P.  rubigo-vcra  (DC.), 
Wint.,  also  P.  glumarum  (Schum.),  Eriks.  &  Henn.). 
Descr.  lUus.,  Ind.  Agr.  Exp.  Sta.,  Bull.  26  (1889). 

Kan.  Agr.  Exp.  Sta.,  Bull.  38,  pp.  1-3  (1893). 
Treat,  (rec),  Idaho  Agr.  Exp.  Sta.,  Bull.  11,  pp.  33-34  (1898). 
Cf.  U.  S.  Dept.  Agr.,  Div.  Veg.  Phys.  &  Path.,  Bull.  16  (1899). 
Scab  {Cladosporium  herbarum  (Pers.),  Lk.). 

Scab  (Fusarium  culniorum  (E.  F.  Sm.),  Sacc.=i^.  rubiginosuni,  Appel  &  Wollenw.). 
Descr.  Illus.,  Del.  Agr.  Exp.  Sta.,  Rep.  3,  1890,  pp.  89-90  (1891). 
Ohio  Agr.  Exp.  Sta.,  Bull.  44,  pp.  147-148  (1892). 
Scab  {Gibberella  Saubenetii  (Mont.),  Sacc,  Stage  oi  Fusarium  roseum,  Lk.). 

Descr.  Illus.,  Ohio  Agr.  Exp.  Sta.,  Bull.  97,  pp.  40-42  (1898). 
Stinking-smut  {Tilletia  fcetens  (Bri.  &  Cav.),  Schrt,  T.  tritici  (Bjerk.),  Wint.). 

Phytopath.  6,  pp.  21-28  (1916). 
Loose-smut  (Uslilago  tritici  (Pers.),  Jens.). 

Descr.  Illus.,  Kan.  Agr.  Exp.  Sta.,  Rep.  2,  1889,  pp.  261-267  (1890). 
N.  Dak.  Agr.  E.xp.  Sta.,  Bull.  1,  pp.  9-20  (1891). 
U.  S.  Dept.  Agr.,  Farm.  Bull.  75,  pp.  6-8  (1898). 
Treat,  (pos.),  Ohio  Agr.  Exp.  Sta.,  Bull.  97,  pp.  60-61  (1898). 

U.  S.  D^pt.  Agr.,  Farm.  Bull.  75,  pp.  11-14  (1898). 

Willow 
(Salix  spp.) 

Black-spot  {Rhytisma  salicinum  (Pers.),  Fr.). 

Duggar,  p.  209  (1909). 
Crown-gall  {Pseiidomonas  tumefaciens,  E.  F.  Sm.  &  Towns.). 

Duggar,  p.  114  (1909). 


LIST   OF    SPECIFIC   DISEASES    OF    PLANTS  473 

Decay,  or  Brown-rot  (Poly poms  stdphHreus  (Bull.),  Fr.). 

Duggar,  p.  457  (1909)- 
Powdery  Mildew  {Undnula  salicis  (DC),  Wint.). 

Duggar,  p.  230  (1909). 
White-rot  (Polyporus  sqnamosus  (Huds.),  Fr.)- 

Duggar,  p.  453  (1909). 
Rust  {Mdampsora  salickaprce  (Pers.),  Wint.)   =M.  Jariiiosa  (Pers.),  Schrot. 

Zinnia 

{Crassina  ckgam  (Jacq.)  Kze.) 

Leaf-spot  {Ccrcospora  atrkincta,  Heald  &  Wolf). 

Heald  &  Wolf,  Plant  Disease  Survey  in  Texas  (191 2). 

BIBLIOGRAPHY  OF  SPECIFIC  PLANT  DISEASES 

That  the  foregoing  list  may  be  made  as  useful  to  American  students  as  possible, 
a  partial  bibliography  of  some  of  the  publications  dealing  with  specific  diseases  of 
our  economic  plants  is  herewith  given. 

Arthur,  Joseph  C.  and  Kern,  F.  D.:  North  American  Species  of  Peridermium  on 

Pine.     Mycologia,  vi:  109-138,  May,  1914. 
Clinton,  G.  P.:  The  Smuts  of  Illinois  Agricultural  Plants.     Univ.  111.  Agric.  Exper. 

Sta.,  Bull.  57,  March,  1900. 
Cook,  Mel  T.:  Potato  Diseases  in  New  Jersey,  N.  J.  Agric.  Exper.  Sta.,  Circular  33. 
Cook,  Mel  T.:  Common  Diseases  of  the  Peach,  Plum  and  Cherry.     N.  J.  Agric. 

Exper.  Sta.,  Circular  45. 
Cook,  Mel  T.:  Common  Diseases  of  Apples,  Pears  and  Quinces.     N.  J.  Agric. 

Exper.  Sta.,  Circular  44. 
Duggar,   B.'  M.:  Some  Important  Pear  Diseases.     Cornell  Univ.  Agric.   Exper. 

Sta.,  Bull.  145,  February,  1898. 
Duggar,  B.  M.:  Three  Important  Fungous  Diseases  of  the  Sugar  Beet.     Cornell 

Univ.  Agric.  Exper.  Sta.,  Bull.  163,  February,  1899. 
Edgerton,    C.   W.:  Some  Sugar   Cane  Diseases.     La.   Agric.   Exper.   Sta.,    Bull. 

120,  1910. 
Eugerton,   C.  W.:  Disease  of  the  Fig  Tree  and  Fruit.     La.  Agric.  Exper.  Sta., 

Bull.  126,  March,  1911. 
Freeman,  E.  M.,  and  Johnson,  E.  C:  The  Loose  Smuts  of  Barley  and  Wheat. 

U.  S.  Bureau  of  Plant  Industry,  Bull.  152,  1909. 
Freeman,  E.  M.,  and  Johnson,  E.  C:  The  Rusts  of  Grain  in  the  United  States, 

.  U.  S.  Bureau  of  Plant  Industry,  Bull.  216,  1916. 
Freeman,  E.  M.  and  Stakman,  E.  C:  The  Smuts  of  Grain  Crops.     Minn.  Agric. 

Exper.  Sta.,  Bull.  122,  February,  1911. 
Harter,  L.  L.:  Sweet  Potato  Diseases.     U.  S.  Farmers'  Bull.  714,  March  11,  1916. 
Hesler,  Lex  R.,  and   Whetzl,  Herbert  H.:  Manual  of   Fruit  Diseases,    191 7. 

The  MacMillan  Co. 


474  SPECIAL   PLANT    PATHOLOGY 

Johnson,  E.  C:  Timothy  Rust  in  the  United  States.  U.  S.  Bureau  of  Plant  In- 
dustry, Bull.  224,  191 1. 

Orton,  W.  a.:  Some  Diseases  of  the  Cowpea.  U.  S.  Bureau  of  Plant  Industry, 
Bull.  17,  1902. 

Orton,  W.  A.:  Tomato  Diseases,  from  Tomato  Culture  by  Will  W.  Tracy, 
1907,  Orange  Judd  Co. 

Orton,  W.  A.:  Potato  Tuber  Diseases.     U.  S.  Farmers'  Bull.  544,  1913. 

Pool,  Venus  W.:  Some  Tomato  Fruit  Rots  during  1907,  1908. 

Reed,  Howard  S.  and  Crabill,  C.  H.:  Notes  on  Plant  Diseases  in  Virginia  ob- 
served in  1913  and  1914.    Va.  Agric.  Exper.  Sta.,  Tech.  Bull.  2,  April,  1915. 

Selby,  a.  D.:  Some  Diseases  of  Orchard  and  Garden  Fruits.  Ohio  Agric.  Exper. 
Sta.,  Bull.  79,  1897. 

Selby,  A.  D.:  Prevalent  Diseases  of  Cucumbers,  Melons  and  Tomatoes.  Ohio 
Agric.  Exper.  Sta.,  Bull.  89,  December,  1897. 

Shear,  C.  L.  :  Cranberry  Diseases.     U.  S.  Bureau  of  Plant  Industry,  Bull.  1 10,  1907. 

Stevens,  F.  L.:  Fungous  Diseases  of  Apple  and  Pear.  N.  C.  Agric.  Exper.  Sta., 
Bull.  206,  March,  1910. 

Stone,  Geo.  E.:  Tomato  Disease.     Mass.  Agric.  Exper.  Sta.,  Bull.  38,  June,  191 1. 

Taubenhaus,  J.  J.:  Diseases  of  the  Sweet  Pea.  Del.  Agric.  Exper.  Sta.,  Bull. 
106,  November,  19 14. 

VON  Schrenk,  Hermann:  Two  Diseases  of  Red  Cedar  caused  by  Poly  poms 
jtmiperinus  and  P.  carneus.     U.  S.  Div.  Veg.  Physiol.  &  Pathol.,  Bull.  21, 1900. 

VON  Schrenk,  Hermann:  The  Decay  of  Timber  and  Methods  of  Preventing  It. 
U.  S.  Bureau  of  Plant  Industry,  Bull.  14,  1902. 

VON  Schrenk,  Hermann,  and  Spaulding,  Perley:  The  Bitter  Rot  of  Apples. 
U.  S.  Bureau  of  Plant  Industry,  Bull.  44,  1903. 

Wilcox,  E.  Mead:  Diseases  of  Sweet  Potatoes  in  Alabama.  Agric.  Exper.  Sta. 
of  the  Ala.  Polytechnic  Institute,  Bull.  35,  June,  1906. 


CHAPTER  XXXIV 
DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES  OF  PLANTS 

This  section  of  the  book  will  be  devoted  to  a  consideration  of  the 
specific  diseases  of  plants,  and  the  treatment  of  the  subject  has  been 
made  possible  by  a  selection  of  nearly  loo  parasitic  and  non-parasitic 
diseases.  In  this  selection,  several  things  have  been  kept  in  view,  viz., 
the  importance  of  the  disease  over  wide  geographic  areas,  the  system- 
atic relationship  of  the  fungus  in  order  to  connect  up  the  practical  and 
the  systematic  parts  of  the  book,  because  our  knowledge  of  the  disease 
warrants  its  inclusion  in  the  descriptive  part  which  follows.  As  a  con- 
sideration of  the  remedial  measures  used  to  combat  the  disease  was 
omitted  largely  in  the  description  of  plant  diseases  in  general,  it  is  intro- 
duced incidentally  with  the  study  of  specific  plant  diseases.  The  chief 
reference  to  such  remedial  substances  and  their  use  will  be  found  in  one 
of  the  appendices  in  the  back  of  the  book,  where  the  manufacture  of 
sprays  and  washes  and  their  recommended  use  may  best  be  made  with 
the  consideration  of  a  spray  calendar.  A  regular  spraying  program 
is  now  considered  a  necessity  by  every  successful  plant-grower,  the 
expense  of  which,  treated  as  insurance,  can  no  more  be  escaped  than  the 
outlay  for  cultivation,  manures,  or  pruning.  In  the  control  of  plant 
enemies,  including  both  insect  pests  and  fungous  parasites,  there  are 
essential  points  in  practice  which  may  not  be  evaded  or  neglected, 
namely:  To  spray  at  the  correct  time  (hence  the  need  of  a  calendar)  to 
use  the  proper  form  and  strength  of  spray  (hence  the  need  of  formulae) 
and  to  make  a  thorough  covering  of  the  parts  sprayed.  Hence  that 
important  branch  of  phytopathology  known  as  therapeutics  will  be 
mentioned  incidentally  in  part  III  and  treated  in  detail  in  the  latter  part 
of  part  IV. 

The  description  of  each  disease  will  be  given  in  condensed  form  pur- 
posely, so  that  the  student  of  plant  pathology  who  wants  to  know  more 
about  the  specific  diseases  of  some  particular  crop  in  which  his  interest 
has  been  aroused  will  be  compelled  to  study  the  literature  and  thus  gain 

475 


476  SPECIAL   PLANT   PATHOLOGY 

access  to  the  most  important  work  which  has  been  done.  In  this  inves- 
tigation, the  student  should  write  descriptions  of  the  diseased  host 
plants  and  parasitic  organisms  concerned,  according  to  the  method  out- 
lined in  part  IV,  pages  639  to  642,  and  together  with  this  detailed  de- 
scription he  should  compile  a  bibliography. 

Pedagogically  it  is  a  mistake  to  give  too  full  details  in  a  text-book, 
because  the  student  learns  to  depend  on  the  statements  in  the  book 
rather  than  on  original  observations  of  his  own.  The  compilation  of  a 
bibliography  becomes  an  important  adjunct  to  all  successful  phyto- 
pathologic  work.  "Study  things,  not  books"  is  a  truism  in  this  depart- 
ment of  scientific  knowledge,  as  in  other  departments  of  natural  science. 
The  teacher  should  so  guide  and  stimulate  the  class  of  students  that  each 
member  of  the  class  will  be  led  to  independent  study  and  investigation, 
so  that  they  may  be  able  to  apply  individually  the  modicum  of  knowledge 
which  the  strictures  of  the  time  allotted  to  the  subject  in  the  college  has 
permitted  them  to  obtain.  Unless  this  independence  of  thought  and 
action  is  secured,  the  results  of  the  teaching  have  not  been  satisfactory. 
It  is,  therefore,  hoped  by  the  writer  of  this  text-book  that  what  has  been 
included  in  its  pages  will  be  directive  and  helpful  to  teacher  and  student 
rather  than  a  work  of  encyclopedic  value.  The  subject  of  phytopa- 
thology is  such  a  vast  one,  that  it  would  be  impossible  without  the  coop- 
eration of  a  large  number  of  specialists  to  make  a  work  which  would  be 
of  encyclopedic  value.  The  design  of  this  text-book  has  been  to  give  an 
outline  of  the  subject,  so  that  the  attention  of  the  student  may  be  direc- 
ted to  the  important  phases  of  the  subject  of  phytopathology. 

Alfalfa  {Mcdicago  sativa  L.) 

Leaf-spot  {Pseudopeziza  medicaginis  (Lib.),  Sacc). — The  fungus 
which  causes  this  widely  prevalent  disease,  where  alfalfa  is  grown, 
belongs  to  a  genus  in  which  the  apothecium  is  formed  beneath  the  epi- 
dermis and  as  it  grows  it  breaks  through  the  epidermal  covering  and 
emerges  as  a  shallow,  relatively  simple  structure  with  asci  that  contain 
eight  one-celled  spores.  It  is  related  to  a  similar  fungus  Ps.  trifolii, 
which  attacks  the  leaves  of  clovers.  It  forms  small  brown,  or  black, 
spots  on  the  upper  leaf  surface  usually.  These  spots,  which  are  about 
2  mm.  in  diameter,  represent  the  sessile  apothecia,  which  are  sprinkled 
pretty  copiously  over  the  leaf  surface  in  the  latter  part  of  summer. 


DETAILED   ACCOUNT   OF    SPECIFIC   DISEASES    OF   PLANTS      477 

The  unicellular  spores  measure  10  to   14/i  in  length.     No  practical 
method  has  been  devised  for  controlling  the  alfalfa  leaf-spot  disease. 

Rust  {Uromyces  striatus  Schrot.). — The  aecidiaof  this  rust  are  found 
on  Euphorbia  cyparissias  in  Europe  and  in  Great  Britain  the  uredinea 
and  telia  occur  on  a  clover  Trifolium  minus.  In  California,  it  forms 
reddish-brown,  dusty  pustules  on  the  surfaces  of  alfalfa  leaves  and 
in  wet  weather  it  may  be  destructive  to  the  crop,  but  in  dry  weather 
it  usually  disappears.  The  spots  are  on  close  examination  seen  to  be 
cinnamon-colored,  due  to  the  presence  of  globose  to  ellipsoid,  faintly 
echinulate,  yellowish-brown  uredospores,  which  measure  15  to  22// 
with  a  spore  wall  i  to  2^  thick,  and  with  four  to  six  germ  pores  each 
with  a  small  cap.  The  telia  are  darker  in  color,  and  the  teliospores  are 
globose  to  ovate  with  a  minute  papilla  striated  from  apex  to  base  with 
lines  of  brown  warts  and  measure  18  to  24  by  15  to  20/x  with  an  epir 
spore  1 3^  to  2/i  thick.  The  best  way  of  combating  this  disease  is  to 
cut  and  burn  badly  affected  crops.  Frequent  close  mowing  is  useful 
in  checking  leaf-spot. 

Apple  {Pyrus  malus  L.) 

Bitter-rot  {Glomerella  cingulata  (Stonem.)  S.  &  V.  S.). — This 
fungus,  which  in  some  text-books  is  known  as  G.  rufomaculans  (Berk.) 
Spauld.  &  von  Sch.,  causes  one  of  the  most  serious  losses  in  the  apple- 
growing  districts  of  the  United  States  (Fig.  190).  It  is  distributed 
widely,  particularly  eastward  of  the  arid  portions  of  the  country  and 
its  effects  are  seen  during  July  and  August  and  later,  especially  during 
warm  rainy  weather,  which  produce  sultry  conditions  of  the  atmos- 
phere, when  the  age  of  the  fruits  is  such  as  to  render  them  especially 
susceptible.  Cold  weather  acts  as  a  check  to  the  spread  of  the  dis- 
ease. The  fruit  is  attacked  chiefly,  but  the  branches  may  also  become 
diseased. 

The  disease  first  appears  as  a  small  brown  spot  beneath  the  skin  of 
the  apple,  which  increases  gradually  in  size,  keeping  nearly  a  circular 
outline  with  a  well-defined  margin.  The  central  part  of  the  spot  soon 
becomes  sunken  and  this  is  accompanied  by  the  spread  of  the  fungus 
throughout  the  fruit  and  the  formation  of  pustules.  Decay  soon  sets 
in  and  the  products  of  the  decay  are  invariably  bitter.  The  fruits,  if 
attacked  on  the  tree,  later  fall  off,  but  sometimes,  they  hang  on  and 
become  mummified.     Two  stages  in  the  life  history  of  the  fungus  have 


478  SPECIAL   PLANT   PATHOLOGY 

been  discovered.  The  gleosporial,  or  imperfect  stage,  usually  develops 
on  the  fruit,  while  the  ascigeral  stage  is  occasionally  produced  on  a 
fruit  or  twig,  and  in  artificial  cultures  is  readily  obtained.  Early  in- 
fection of  the  fruit  is  probably  due  to  the  spores  produced  in  pustules 
on  the  areas  of  stem,  which  have  become  cankered  through  the  attack 
of  the  bitter-rot  mycelium.  Such  cankers  are  sunken  areas  upon  twigs 
or  limbs,  accompanied  by  a  cracking  and  breaking  of  the  bark  over  such 
regions.  The  pustules,  which  accompany  the  rot  of  the  fruit,  are  formed 
beneath  the  apple  skin  as  ccmdensed  masses  of  the  mycelium  known 
as  stroma  and  these  emerge  as  a  cone-shaped  mass  of  erect  hyphae, 
which  are  the  conidiophores,  which  cut  off  conidiospores  that  emerge 
as  a  pink  waxy  strand,  later  becoming  of  a  gray  color.  The  ovate  to 
oblong  conidiospores,  which  measure  in  extreme  cases  6  to  40  by  3.5 
to  7/1,  more  usually  12  to  16  by  4  to  6/i,  are  imbedded  in  a  gelatinous 
matrix  which  dissolves  in  water  setting  the  spores  free.  These  spores 
germinate  freely  and  become  septate  in  doing  so.  Infection  of  apple 
fruits  may  be  through  the  uninjured  skin,  but  a  slight  abrasion  facilitates 
the  entrance  of  the  germ  tube  of  the  spore.  Berkeley,  who  first 
described  this  stage,  named  it  Gleosporium  Jructigenum  and  under  this 
scientific  name  the  disease  is  frequently  quoted. 

Clinton  discovered  the  perithecial  stage  in  1902,  and  as  it  is  readily 
obtained  in  cultures  on  any  of  the  ordinary  nutrient  media  its  character- 
istics are  well-known.  The  perithecia  which  are  developed  contain 
oblong-clavate  asci,  55  to  70  by  g/x,  which  develop  eight  curved  asco- 
spores,  usually  uniform  in  size,  12  to  22  by  3.5  to  5/1.  The  pomologist, 
who  wishes  to  control  the  disease,  should  prune  away  all  cankered  limbs 
and  keep  the  orchard  free  of  diseased  fruits.  The  spraying  of  the  trees 
with  Bordeaux  or  lime-sulphur  (3-3-50)  has  been  found  efficacious, 
and  the  crop  returns  from  sprayed  trees,  as  contrasted  with  unsprayed 
trees,  have  abundantly  repaid  the  trouble  which  the  orchardist  has 
taken  in  the  application  of  Bordeaux  mixture.  The  first  application 
of  the  spray  should  be  in  the  form  of  a  mist  about  a  month  after  the 
petals  have  fallen  and  subsequent  applications  should  be  made  about 
two  weeks  apart  until  at  least  five  sprayings  have  been  made. 

Black-rot  {Spharopsis  malorum  Berk.). — Although  the  apple  is 
one  of  its  host  plants,  the  black  rot  fungus  attacks  other  pomaceous 
trees,  producing  cankers  so  that  the  description  of  the  disease  and 
fungus,  as  applied  to  the  apple,  will  serve  with  certain  modifications  for 


DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES   OF  PLANTS       479 

the  other  pomaceous  trees  as  well,  and  this  may  be  said  of  several  of 
the  other  diseases  treated  of  here  that  the  description  of  a  disease  as 
specifically  affecting  a  certain  host,  might  equally  apply  to  several 
other  host  plants.  The  black-rot  fungus  not  only  causes  a  fruit 
decay  of  apples,  quinces  and  pears,  but  it  causes  the  formation  of 
canker  on  the  limbs  of  these  trees.  The  fruit  rot  is  the  generally 
recognized  form  of  the  disease.  The  disease  begins  as  a  small  spot 
sometimes  near  the  bud  end  of  the  fruit  and  it  spreads  until  the  whole 
fruit  is  involved.  The  apples  do  not  shrink,  as  in  the  former  disease. 
The  canker  form  of  the  disease  on  the  bark  of  the  trees  is  accompanied 
by  either  a  roughening  of  the  bark  in  mild  forms  of  the  disease,  or  in 
more  virulent  forms  by  a  destruction  of  the  bark  with  the  formation 
of  depressed  areas  about  which  local  swellings  of  the  limbs  occur. 

The  sooty  brown,  or  olivaceous,  mycelium  penetrates  the  bark 
of  the  tree,  hardly  extending  into  the  wood.  It  soon  forms  pycnidia 
which  are  erumpent  and  surrounded  by  the  remnants  of  the  epidermis. 
The  pycnospores  are  oblong-elliptic,  22  to  32  by  10  to  141JL,  brown  in 
color,  and  their  size  varies  with  the  host  plant  on  which  the  fungus  lives. 
Artificial  cultures  of  the  fungus  have  successfully  produced  spores. 
Lime-sulphur  solution  has  been  found  useful  in  combating  the  disease, 
but  pruning  and  scraping  the  trees  should  not  be  neglected. 

Scab  {Venturia  inequalis  (Cke.)  Wint.). — The  scab  also  appears  on 
the  pear,  but  mycologists  now  consider  that  the  scab  fungus  of  the 
apple  is  specifically  distinct  from  that  of  the  pear.  Earlier  mycologist^ 
were  familiar  with  the  conidial  forms  of  the  two  fungi,  and  they 
were  placed  under  the  genus  Fusicladium,  as  F.  dendriticum  and 
F.  pyrimim,  but  since  the  perfect  stages  have  been  discovered  the 
species  have  been  put  in  the  genus  Venturia.  The  perithecial  stage 
is  saprophytic.  Scab  is  found  wherever  the  apple  is  grown  from 
Maine  to  California. 

The  fungus  mainly  attacks  the  fruit  and  leaves  of  the  apple,  but 
it  has  been  found  on  the  flowers,  flower  stalks  and  twigs.  The  leaf 
spots  are  more  abundant  on  the  lower  surface,  but  sometimes  also  on 
the  upper  surface,  as  a  velvety,  olivaceous,  superficial  growth,  occasion- 
ally accompanied  by  a  curling  of  the  leaf.  The  fruit  spots  are  at  first 
small  and  olivaceous,  and  as  the  mycelium  spreads  the  epidermis  is 
killed  and  the  scabby  areas  arise  (Figs.  164  and  165).  Nearly  all  varie- 
tes  of  apple  and  pear  are  susceptible,  but  there  is  a  varietal  difference 
in  this  susceptibility. 


48o 


SPECIAL   PLANT   PATHOLOGY 


The  hyphae  grow  beneath  the  epidermis  and  between  the  epidermis 
and  cuticle  spreading  slowly.  The  erect  conidiophores,  which  are 
produced,  rupture  the  epidermis,  giving  the  characteristic  velvety, 


Fig.  164. — Two  apples  affected  with  scab  {Venliiria  inequalis),  showing  spots, 
deformation  and  reduction  in  size  of  the  fruit.  {After  Heald,  F.  D.,  Bull.  35  {Sci. 
Ser.  14),  Univ.  of  Tex.,  Nov.  15.  1909.) 


Fig.  165. — Two  apples  affected  with  scab  {Vcnluria  inequalis),  showing  spots, 
deformation  and  reduction  in  size  of  the  fruit.  {After  Heald,  F.  D.,  Bull.  135  {Set. 
Ser.  14),  Univ.  of  Tex.,  Nov.  15,  1909.) 


olivaceous  character  to  the  spotted  surface,  and  as  the  scabby  areas 
are  formed,  the  epidermis  disappears.  Conidiospores  arise  at  the  tips 
of  the  conidiophores  and  in  concatenation.     These  spores  are  ovate, 


DETAILED  ACCOUNT   OF   SPECIFIC  DISEASES   OF  PLANTS 


truncate  at  the  base  and  measure  28  to  30ju  by  7  to  9/1.  According  to 
Clinton,  they  do  not  retain  their  vitality  long.  An  investigation  of 
perithecial  formation  indicates  that  perithecia  begin  to  form  in 
October,  or  even  later,  and  reach  maturity  in  the  following  April, 
when  mature  ascospores  have  been 
found  especially  on  the  under  sur- 
faces of  the  leaves.  They  are  im- 
bedded in  the  leaf  tissues  and  are 
slightly  pyriform  in  shape,  includ- 
ing clavate  slightly  curved  asci 
measuring  55  to  75//  by  6  to  12^1. 
Each  ascus  contains  eight  two- 
celled  ascospores,  which  are  olive- 
brown  in  color  with  the  following 
dimensions:  11  to  15/iby  5  to  7/x. 
They  germinate  readily  in  water. 
Spraying  with  lime-sulphur 
mixture  32°  Beaume,  1-40,  before 
the  time  of  flowering  has  been  rec- 
ommended for  Scab,  followed  by 
a  second,  or  even  a  third  spraying 
after  the  petals  fall,  and  at  least 
two  or  three  weeks  after  the 
second. 


Ash  (Fraxinus  americanus,  L.) 

Heart-rot  (Fomes  fraxinophilus 
(Pk.)  Sacc). — In  the  Mississippi 
Valley,  white  ash  trees  of  all  ages 
are  attacked  by  this  bracket 
fungus,  which  is  a  tree  wound 
parasite,  entering  usually  the  stub 

of  a  branch,  which  has  been  broken  off  by  the  wind,  or  by  snow.  From  the 
point  of  entrance,  the  mycelium  grows  into  the  heartwood  of  the  trunk. 
The  wood  at  first  turns  darker  in  color,  later  the  disease  is  marked 
by  a  bleaching  of  the  color  in  the  spring  wood  of  the  annual  rings,  which 
turn  to  a  straw  color  and  then  become  blanched.  The  whole  woody 
31 


Fig.  166. — An  old  sporophore  of  Fomes 
(Polyporus)  fraxinophilus  on  white  ash. 
(After  Herynann  von  Schrenk,  Bull.  32, 
U.  S.  Bureau  of  Plant  Industry.  1903.) 


482 


SPECIAL   PLANT   PATHOLOGY 


Fig.  167. — Disease  of  ash  caused  by  Fames  (Polyporus)  fraxinophilus.  i,  Cross- 
section  of  ash  wood;  2,  of  medullary  ray;  3,  medullary  ray,  showing  later  stage  of 
attack;  4,  5,  of  wood  cells;  6,  starch  grains  from  medullary  ray  cell;  7  diseased 
wood;  8,  transection  from  entirely  rotted  wood.  (After  von  Schrenk,  Hermann, 
Bull.  32,  U.  S.  Bureau  of  Plant  Industry,  1903) 


DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES   OF  PLANTS       483 

tissue  becomes   straw-colored   and   finally   transformed  into  a  loose 
spongy  mass  of  fibers,  which  readily  absorbs  water  (Fig.  167). 

The  fruiting  brackets,  or  sporophores,  make  their  appearance  from 
the  mycelium  at  the  base  of  the  stubs,  or  from  wounded  surfaces, 
either  alone,  or  a  number  together  (Fig.  166).  The  mature  sporophore, 
according  to  von  Schrenk,^  is  nearly  triangular  in  cross-section  with  a 
broad  rounded  edge,  which  at  first  is  white,  turning  gradually  darker 
until  it  becomes  straw-colored  (Fig.  167).  The  older  portions  of  the 
upper  surface  are  dark  brown,  or  black,  and  are  very  hard  and  woody, 
its  upper  surfaces  obscurely  zoned,  pale  brown  and  rust  colored.  Wound 
protection,  as  outlined  in  the  section  on  prophylaxis,  is  an  important 
method  of  preventing  the  white  heart-rot  from  killing  white  ash  trees. 

Asparagus  (Asparagus  officinalis,  L.) 

Rust  {Puccinia  asparagi  DC.) — The  asparagus  rust  is  well-known, 
having  been  investigated  by  a  number  of  mycologists  in  this  country, 
notably  Halsted,  Sirrine,  Smith  and  Stone. ^  In  Europe  the  disease  is 
of  little  consequence,  but  in  America  it  threatens  the  asparagus  growing 
of  our  country,  spreading  rapidly,  especially  during  times  when  dew  is 
abundant,  for  Smith  says:  "The  amount  of  rust  varies  directly  and 
exactly  with  the  amount  of  dew,  and  so  long  as  there  is  little  or  no  dew, 
there  can  be  no  rust."     During  dry  summers  rust  is  largely  absent. 

All  of  the  spore  forms  are  found  on  the  stems  and  twigs  of  the  culti- 
vated asparagus  and  on  several  wild  species  of  the  genus.  The  uredi- 
nia  and  telia  appear  also  on  the  leaf-like  branches  of  the  plant.  The 
aecidia  appear  as  long  light-green  cushion-like  patches.  They  have  a 
white  peridium  and  are  short  cylindric,  inclosing  the  orange-colored 
aeciospores,  which  are  15  to  iS/z  in  diameter,  and  retain  their  power  of 
germination  for  several  weeks.  Stomatal  infection  probably  is  the  rule. 
Associated  with  these  secia  are  spermagonia  in  small,  yellow  clusters. 
Early  summer  ushers  in  the  red  rust  (uredo)  stage  of  the  disease  with 
the  deep  brown  sori  more  or  less  scattered  at  first,  later  becoming  con- 
fluent. The  urediniospores  are  yellowish-brown,  thick-walled  with 
four  germ  pores  and  measure  21  to  24^.     The  clothing  of  a  person 

Won  Schrenk,  Hermann  and  Spaulding,  Perley:  Diseases  of  Deciduous 
Forest  Trees.     Bull.  149,  U.  S.  Bureau  of  Plant  Industry. 

''Smith,  Ralph  E.:  Asparagus  and  Asparagus  Rust  in  California.  Calif.  Agric. 
Exper.  Sta.,  Bull.  165:  1-95,  1905. 


484  SPECIAL  PLANT   PATHOLOGY 

rubbing  against  the  plant  may  be  colored  owing  to  the  abundance  pro- 
duced. Later  in  the  season  the  black  rust  stage  appears  with  the  forma- 
tion of  elliptic  two-celled  teliospores,  30  to  dofx  by  21  to  28/i,  and  with 
a  thickened  apex  and  long  pedicels.  Infection  of  asparagus  plants  in 
cultivated  fields  is,  according  to  Duggar/  through  the  aeciospores  pro- 
duced on  wild  or  escaped  plants  and  not  directly  from  the  germination 
of  the  teliospores,  which  remain  in  or  about  the  soil.  Bordeaux  mix- 
ture, used  as  a  spray  alone,  has  not  been  very  successful.  A  more 
successful  treatment  has  been  obtained  by  adding  a  resin  mixture  to 
the  Bordeaux  solution.  Sirrine  recommends  the  following:  Bordeaux 
mixture,  5-5-40  formula,  40  gallons;  resin  mixture,  2  gallons,  diluted 
10  gallons.  The  resin  mixture  consists  of  resin  5  pounds;  potash  lye  i 
pound;  fish  oil  i  pint;  and  water  5  gallons.  Under  certain  climatic  con- 
ditions in  California  it  has  been  found  efficient  to  dust  the  young  tops 
with  dry  powdered  sulphur  on  a  dewy  morning  at  the  rate  of  one 
and  a  half  sacks  of  sulphur  per  acre,  followed  in  a  month  by  a 
second  application,  using  two  sacks  of  sulphur  per  acre. 

Banana   {Musa  sp.) 

Bud-rot  {Bacillus  musce,  Rorer). — Bud  rots  of  the  banana  have 
been  reported  from  the  greater  Antilles  (Cuba,  Jamaica)  from  Central 
America  and  Trinidad.  The  disease  in  Trinidad  has  been  investigated 
by  a  mycologist  from  the  United  States,  J.  B.  Rorer,  the  mycologist 
of  the  island  government,  and  he  has  proved  that  an  organism  which 
he  has  isolated  and  named  Bacillus  musce  is  the  responsible  parasite. 
However,  the  bud-rots  of  the  banana  are  probably  due  to  the  same 
cause,  but  the  matter  has  not  been  investigated  satisfactorily  outside 
of  Trinidad.  The  disease  usually  appears  on  the  young  plants,  attack- 
ing the  young  leaves  and  the  core,  which  become  brown.  The  tissues 
disorganize  and  a  putrid  rot  sets  in  with  the  death  of  the  parts 
attacked. 

March  is  the  month  in  which  the  disease  usually  begins  and  in 
three  or  four  months  its  destructive  effects  are  seen. 

Beet  (Beta  vulgaris,  L.) 

Leaf -spot  (Cercospora  beticola,  Sacc). — This  disease  is  distributed 
widely  in  America  and  Europe  and  the  red  garden  beet  is  seldom  free 
^  DuGGAR,  B.  M.:  Fungous  Diseases  of  Plants,  406. 


DETAILED  ACCOUNT  OF   SPECIFIC  DISEASES   OF  PLANTS       485 

from  it.  The  leaf-spots  are  very  small  brown  with  reddish-purple 
borders,  when  they  first  appear,  and  later,  when  about  4  mm.  in 
diameter,  they  become  ashen  gray  at  the  center  with  the  usual  margin. 
They  are  scattered  over  the  blade  and  eventually  the  leaves  blacken 
and  dry  up,  and  as  the  lower  leaves  die,  new  ones  are  formed  above 
until  a  characteristic  elongated  crown  may  be  produced.  The  gray 
color  of  the  spots  is  usually  associated  with  the  formation  of  conidio- 
sphores-  and  conidiospores.  The  conidiophores  are  clustered,  arise 
from  a  few-celled  stroma,  and  push  through  the  leaf  stomata.  The 
conidiospores  are  elongated  and  needle-shaped,  multicellular,  75  to 
200/1  by  3.5  to  4.SAi,  and  under  moist  conditions,  the  average  length  may 
be  exceeded.  They  germinate  readily  in  ordinary  nutrient  media 
and  the  submerged  mycelium  in  agar  grows  as  a  dense  colony  oliva- 
ceous in  color,  while  the  aerial  portion  is  grayish-green.  The  disease 
fortunately  can  be  controlled  by  the  use  of  Bordeaux  mixture  (4-4-50), 
and  as  the  spores  retain  their  vitality  for  some  time,  early  spraying 
is  important  and  frequent  after  sprayings. 

Rust  {Uromyces  betcB  (Pers.),  Tub). — The  beet  rust  is  known  only 
from  California.  It  is  common  in  Australia  and  not  unusual  in 
Europe.  Klihn  thinks  that  the  mycelium  may  be  biennial  in  the  host, 
forming  aecia  throughout  the  year.  The  spermogonia  are  found  in 
small  yellow  groups  associated  with  the  Eecia,  which  are  white  and 
saucer-shaped  with  aecidiospores  17  to  36/i  in  diameter,  filled  with 
orange-colored  contents.  The  uredinia  and  telia  are  irregularly  scat- 
tered over  the  leaf  surfaces.  The  urediniospores  are  obovate,  21  to 
24|U  by  35M  with  echinulate  walls,  and  two  opposite  germ  pores.  The 
short  pedicellate  obovate  -teliospores  are  18  to  24/i  by  25  to  32/x, 
with  an  apical  germ  pore  piercing  a  wall  scarcely  thicker  at  the  apex. 

Cabbage  (Brasska  oleracea,  L.) 

Black-rot  (=  Pseudomonas  brassicce.  (Pam.),  Sm.,  Bacterium  cam- 
pestris  (Pam.),  Sm.)  — The  cause  of  the  black-rot  of  cabbage  and  other 
cruciferous  plants  is  a  yellow,  uni-flagellate  microorganism,  which  causes 
a  yellowing  of  the  cabbage  leaves  accompanied  by  a  black  stain  in  the 
vascular  system,  forming  a  conspicuous  black  network  on  a  yellowish, 
or  light-brown,  background.  The  badly  diseased  leaves  are  shed,  so 
that  the  stem  may  have  a  terminal  tuft  of  badly  distorted  leaves. 


486 


SPECIAL   PLANT   PATHOLOGY 


A  stem  section  shows  a  browning  of  the  vascular  ring  and  the  vessels 
are  found  occupied  by  bacteria  (Fig.  i68).  When  the  cabbage  plant 
is  attacked  early  in  the  season,  it  is  killed  outright,  or  else  it  fails 
to  form  the  characteristic  head.  Infections  may  take  place  through 
injury  of  the  surface,  but  the  greater  part  of  them  are  through  the 
water  pores,  which  exude  drops  of  water,  which   collect  during  cool 


Fig.  i68. — Brown-rot  of  turnip  (Pseudomonas  brassica).  Cross-section  from 
middle  of  turnip  root  showing  small  bundle  fully  occupied  by  the  bacterial  organism. 
{After  Smith,  E.  F.,  Bull.  29,  U.  S.  Bureau  of  Plant  Industry,  Jan.  17,  1903.) 


nights,  and  in  natural  infection  slugs  are  responsible  carriers  of  the 
organism. 

Russell  has  found  that  the  cauliflower  is  the  most  susceptible  plant, 
while  turnips  and  rutabagas  are  not  very  susceptible.  Edwards  reports 
that  the  Houser  cabbage  is  practically  immune  to  black-rot  under  field 
conditions.  The  period  of  incubation  is  variable.  In  some  cases  with 
needle  punctures,  the  first  signs  of  the  disease  appear  in  seven   to 


DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES   OF  PLANTS       487 

twenty-eight  days  on  leaves  and  in  from  nine  to  thirty-one  days  on 
stems.  E.  F.  Smith  obtained  with  needle  punctures  first  signs  of 
disease  in  fourteen  to  twenty-one  days.  In  a  study  of  the  morbid 
anatomy  of  the  cabbage,  it  has  been  found  that  the  parasite  is 
confined  for  some  time  to  the  vascular  system  and  even  to  particular 
leaf  traces  or  bundles,  especially  to  the  spiral  and  reticulated  vessels, 
which  are  very  often  filled  with  incalculable  numbers  of  this  organism. 
Later,  as  the  walls  of  the  vessels  are  destroyed,  the  organism  finds  its 
way  into  the  surrounding  parenchyma.  Pseudomonas  brassicoe  is 
sometimes  motile,  especially  when  taken  from  the  plant,  and  is 
examined  in  a  hanging  drop  of  water.  Its  measurements  are  0.7  to 
3.0/i  by  0.4  to  0.5^.  It  is  often  somewhat  irregular  in  shape.  The 
flagella  is  several  times  the  length  of  the  cell  and  arises  at  or  near  the 
end.  The  organism  is  wax-yellow,  changing  to  a  dirty  yellow-brown 
in  old  cultures. 

The  treatment  of  this  disease  falls  principally  under  the  head  of 
restriction  and  prevention.  Seasonal  variations  are  found  and  the 
organism  thrives  well  in  cool,  moist  lands.  Underdrainage  of  soils 
might  prove  advantageous  in  wet  seasons.  The  diseased  plants  should 
not  find  their  way  into  the  manure  heap,  but  all  refuse  should  be  de- 
stroyed. As  E.  F.  Smith  puts  it,  "Avoid  infected  seed,  soil  and  manure; 
destroy  insect  carriers  of  infection,  if  the  plants  are  attacked."  Crop 
rotation  is  advantageous.  Soaking  the  seed  for  fifteen  minutes  in  a 
solution  of  mercuric  chloride  (one  tablet  to  a  pint  of  water)  should  be 
practiced. 

Club-root  {Plasmodiophora  brassiccB,  Wor.)  This  disease,  which 
has  been  known  for  a  hundred  years,  has  received  a  number  of 
names,  such  as  fingers  and  toes,  Anbury,  Hanbury  (England),  Kohl- 
hernie  (Germany),  maladie  digitoire  (France)  Kapoustnaja  Kila 
Russia).  (The  organism  causes  unsightly  and  destructive  root  dis- 
ease of  cruciferous  plants,  such  as  cabbage,  Brussels  sprouts,  turnips, 
rutabagas,  radishes  and  certain  mustards  (Fig.  169).  The  parasite  is 
a  slime  mould  (Myxomycetes)  named  by  Woronin  {Plasmodiophora 
hrassicce).  It  lives  in  the  parenchymatous  cells,  often  in  the  vicinity 
of  the  cambium,  and  an  abnormal  development  of  phloem  is  notice- 
able. The  infested  cells  are  grouped  together  into  packets  and  their 
contents  are  at  first  fluid,  then  turbid  and  granular,  assuming  the 
amoeboid  form  with  distinct  nuclei.     The  amoeba  are  increased  by 


488 


SPECIAL   PLANT   PATHOLOGY 


division,  and  by  a  sort  of  gemmation.  The  myxamoeba  are  provided 
with  several  nuclei.  The  formation  of  spores  soon  begins  by  the  suc- 
cessive simultaneous  divisions  of  the  myxamoebae,  so  that  each  nucleus 
and  surrounding  mass  of  cytoplasm  is  differentiated,  as  a  spore  by  the 
formation  of  a  spore  wall  about  them.     The  diseased  cells  are  crammed 

full  of  such  spores,  which  escape 
only  when  the  root  disintegrates. 
The  liberated  spores  will  germi- 
nate in  water  in  from  four  to 
twenty-four  hours  and  later  the 
parasite  gains  entrance  to  the 
roots  of  the  cabbage  plant.  The 
•organism  causes  an  excessive 
formation  of  new  cells  so  that  a 
gall,  or  canker  results. 

In  order  to  check  the  organ- 
isms, soils  have  been  treated  with 
lime,  sulphur  and  other  fungi- 
cides. Liming,  using  two  tons  of 
c|uicklime  to  the  acre  eighteen 
months  before  planting,  has  been 
found  the  most  reliable  with  the 
destruction  of  the  refuse  of  pre- 
vious crops  by  burning. 


Carnation  (Diani/ms 
caryophyllus,  L.) 


Alterniose    {Alter naria 


Fig.    169. — Cabbage  roots  showing  club- 
root    caused    by    a    parasitic    slime   mould, 
Plasmodiophora  brassicce.      {From  Marshall,    diantki,  Stev.  &  Hall). — Through 
Microbiology.     Second  edition,  p.  609,  after    ^  >•       .     t->  1  •-!-.• 

Woronin.)  y      ^    ^       Connecticut,  Pennsylvania,  Dis- 

trict of  Columbia  and  North 
Carolina  this  disease  of  the  cultivated  carnation  has  been  recently  quite 
troublesome.  The  leaves  and  stems,  especially  at  the  nodes,  are  dis- 
colored with  spots  of  ashen  whiteness  with  a  central  black  fungous 
growth.  The  spot  is  dry,  shrunken  and  thinner  than  the  surrounding 
healthy  parts  of  the  leaf,  and  is  either  circular,  or  somewhat  elongated 
in  Hne  with  the  long  axis  of  the  leaf.     The  nodal  spots  involve  the  leaf 


DETAILED   ACCOUNT   OF   SPECIFIC   DISEASES    OF   PLANTS       489 

bases  as  well,  and  the  mycelium  finally  grows  into  the  stem  killing  its 
tissue  which  becomes  soft  and  broken  down  (Fig.  170).  The  variety 
known  as  Mrs.  Thomas  W.  Lawson  is  especially  susceptible. 

Rust    (Uromyces    caryophyllinus  (Schrank).    Wint. — This    disease 
was  practically  unknown  in  the  United  States  prior  to  1890,  but  now  it 


Fig.  170. — Carnation  alternariose  {Allernaria  dianlhi).  i,  Branched,  septile  my- 
celium; 2,  hyphas  below  surface  of  stroma;  3,  spore  formation;  4,  compound  spores, 
5,  young  clustered  hyphse;  6,  older  cluster.  {After  Stevens,  F.  L.,  and  Hall,  J.  C; 
Bot.  Gas.,  47:  409-413,  May,  1909.) 


is  prevalent  wherever  the  carnation  is  grown  commercially.  The  dif- 
ferent varieties  of  cultivated  carnations  differ  to  a  marked  degree  in 
susceptibility.  Enchantress  and  Lawson  have  a  high  degree  of  resist- 
ance to  rust,  while  Scott  and  Jubilee  are  very  susceptible. 


490  SPECIAL   PLANT   PATHOLOGY 

The  fungus  is  largely  propagated  by  its  urediniospores,  which  are 
ellipsoid  to  spheric  in  form  and  measure  24-35^1  by  21-26/i.  The 
spore  wall  is  thick  and  spinulose.  The  teliospores  resemble  in  form 
the  urediniospores  and  measure  20-35JU  by  18-25/x.  Their  walls  are 
chestnut-brown  and  uniformly  thickened  with  terminal  germ  pores 
and  are  papillate.  As  the  adult  plants  may  be  infected,  the  disease 
may  spread  rapidly  during  the  growing  season. 

The  disease  can  be  controlled  undoubtedly  by  growing  rust-resistant 
varieties  of  carnations.  The  leaves  should  be  kept  away  from  the 
moist  soil  by  simple  V-shaped  wire  mesh  supports  and  lastly  fungi- 
cides, such  as  a  solution  of  copper  sulphate  (i  pound  copper  sulphate 
to  20  gallons  of  water),  might  be  used  with  success,  Duggar  also  rec- 
ommends the  use  of  potassium  sulphide  i  ounce  to  a  gallon  of  water. 
Sub-irrigation  has  been  practised. 

Cacao  (Theobroma  cacao,  L.) 

Brown-rot  (Thyridaria  tarda,  Bancroft). — A  number  of  different 
organisms  have  been  thought  at  different  times  to  cause  the  brown  rot 
of  the  chocolate  pods,  but  Bancroft  in  191 1,  an  authority  on  the  sub- 
ject, ascribed  the  disease  to  the  above-named  fungus.  Circular  brown 
patches  appear  on  the  chocolate  fruits  along  the  grooves  that  seam 
the  surface.  The  disease  spreads  rapidly  and  the  fruit  falls  in  from  six 
to  ten  days  from  the  time  that  it  is  first  infected.  When  the  spots  are 
2  cm.  in  diameter,  their  center  becomes  marked  by  wounds  in  which 
a  brownish-gray  mycelium  appear.  Wounded  fruits  are  especially 
open  to  infection  through  the  abraded  surface  and  the  seeds,  or  beans, 
are  sometimes  involved  and  are  destroyed  completely.  The  disease  is 
widely  spread  in  the  eastern  and  western  tropics  (in  Jamaica,  Santo 
Domingo  and  the  Philippines).  It  may  be  controlled  to  some  extent 
by  burning  all  diseased  fruits,  busks  and  prunings. 

Pink  Disease  {Corticium  lilaco-fuscum,  Berk  &  Curt.). — The  genus 
Corticium  belongs  to  the  family  of  Thelephorace^,  which  includes 
the  smothering  fungi  of  the  genus  Thelephora.  The  leathery  hymeno- 
phore  of  Corticium  is  membranous,  fleshy,  waxy  with  clavate  basidia 
with  four  sterigmata.  The  basidiospores  of  our  cacao  fungus  are 
sessile  on  the  basidia.  It  attacks  the  younger  branches  of  the  chocolate 
tree  covering  them  with  a  pinkish  incrustation,  which  spreads  over 


DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES   OF  PLANTS       49 1 

the  bark  and  into  the  bark  crevices,  causing  the  bark  to  crack  and 
peel.  Later  a  new  bark  forms  under  the  old.  The  new  bark  is  not 
sufficiently  resistant  to  the  attacks  of  species  of  Diplodia  and  Neclria, 
so  that  these  fungi  may  enter  and  complete  the  work  of  destruction. 
Corticium  lilaco-fuscum  grows  more  rapidly  in  damp,  shady  places, 
and  it  usually  refuses  to  grow  in  sunny  places,  hence  opening  up  the 
growth  is  beneficial. 

Cherry  (Prunus  spp.) 

Leaf-curl  (Exoascus  ccrasi  (Fckl.),  Sadeb.).^ — This  fungus  produces 
witches'  brooms  out  of  the  twigs  of  the  cherry,  and  when  the  leaves  on 
affected  twigs  are  parasitized,  they  become  somewhat  reddish  and 
curled.  The  asci  develop  on  the  leaves  and  measure  according  to 
Sadebeck,  35  to  50)uby  7  to  lo/x,  or  in  specimens  studied  by  Atkinson, 
25  to  2)2)1^  by  6  to  9/1.  The  asci  are  naked  and  arranged  in  rows  over  the 
leaf  surface.  Spraying,  if  done  at  all  should  be  done  when  the  buds 
begin  to  develop  in  the  Spring,  and  again  when  the  asci  are  mature 
and  ready  to  discharge  their  spores. 

Powdery  Mildew  (Podosphcera  oxyacanthcB  (DC),  deBy). — This 
disease,  although  found  on  a  number  of  other  rosaceous  plants, 
such  as  plums  and  hawthorns  and  the  like,  is  especially  destructive  to 
apples  and  cherries.  The  leaves  become  mildewed  with  large  spots 
of  white  mycelium  from  which  arise  the  perithecia,  which  are  65  to  90)u 
in  diameter  surrounded  by  the  dichotomously  branched  hyphal  append- 
ages four  to  thirty  in  number,  which  are  usually  five  times  as  long  as 
the  diameter  of  the  perithecium.  A  single  ascus  usually  contains  8 
ascospores.  It  is  recommended  to  spray  with  lime  sulphur  (1-40) 
or  dust  with  powdered  sulphur  in  combating  this  disease. 

Chestnut  (Castanea  dentata  (Marsh.)  Borkh.) 

Blight  {Endothia  parasitica  (Murrill),  Anderson).— When  the  chest- 
nut blight  fungus  was  first  described  by  Murrill  he  called  it  Diaporthe 
parasitica,  but  by  the  studies  of  Anderson  and  others  it  has  been  trans- 
ferred to  the  genus  Endothia,  where  it  seems  rightly  to  belong,^  On 
account  of  its  virulency  and  its  rapid  spread  through  the  chestnut 

1  Shear,  C.  L.,  Stevens,  Neil  E.,  and  Tiller,  R.  J.:  Endothia  parasitica 
and  Related  Species.     Bull.  380,  U.  S.  Dept.  Agric. 


492 


SPECIAL   PLANT   PATHOLOGY 


Fig.  171. — Canker  lesion  that  nearly  surrounds  the  chestnut  branch,  sunken  on 
one  side  and  enlarged  on  the  other.  (,Photo  by  Wm.  Ciirrie,  Bull.  5,  Penna.  Chestnut 
Tree  Blight  Com.,  1913.) 


DETAILED  ACCOUNT  OF   SPECIFIC  DISEASES   OF  PLANTS       493 

forests  of  the  eastern  United  States,  it  has  been  the  subject  of  much 
legislation  and  also  a  copious  bibliography  has  been  formed  by  the 
appearance  of  papers  on  its  parasitism,  life  history  and  the  remedial 
measures  to  be  taken  to  combat  it.     The  chestnut  blight  fungus  was 


Fig.  172. — Perithecial  pustules  of  chestnut  blight  fungus  (Endothia  parasitica) 
in  the  crevices  of  bark  of  a  fallen  chestnut  tree.  (Photo  by  Wm,  Currie,  Bull.  5, 
Penna.  Chestnut  Tree  Blight  Com.,  1913.) 


discovered  by  Merkel  in  1904  on  American  Chestnut  trees  {Castanea 
dentata)  in  the  New  York  Zoological  Park.  It  was  studied  by  Murrill 
during  1906  by  pure  culture  and  by  inoculation  on  healthy  chestnut 
trees,  and  an  account  was  published  of  the  fungus  as  a  new  species  in 
Torreya  (6  :  186-189)  '^^  1906. 


494 


SPECIAL   PLANT   PATHOLOGY 


The  rapidity  of  spread  has  been  phenomenal,  and  the  completeness 
of  destruction  is  without  parallel  in  the  annals  of  plant  pathology.  It 
is  now  found  from  New  Hampshire  to  Albemarle  County,  Virginia,  in 
the  South.  Summer  is  the  best  time  to  study  the  symptoms  of  the 
disease,  which  are  manifested  in  the  brown  shriveled  leaves,  which 
may  be  seen  at  a  distance.  The  dead  leaves  hang  on  the  tree  over 
winter,  and  if  on  the  blighted  branches,  the  girdling  is  completed  while 
the  burs  are  maturing.     Burs  smaller  than  usual,  and  unopened,  re- 


FiG.   173. — Chestnut  blight  pustules  producing  gelatinous  threads  with  summer 
spores.      (After  pictorial  card  issued  by  Penna.  Chestnut  Tree  Blight  Com.,  1912.) 


main  attached  to  the  tree  through  the  winter  months  and  well  into  the 
next  spring.  If,  however,  the  girdling  takes  place  after  the  leaves  and 
burs  are  shed  and  before  the  leaves  open  in  the  spring,  the  leaves  do 
not  attain  their  full  size,  but  are  pale  and  distorted  and  this  is  a  com- 
mon symptom  during  May  and  June.  Dead  limbs  without  attached 
leaves,  or  burs,  are  often  indications  of  the  canker  disease.  Water 
sprouts,  or  suckers,  may  develop  just  below  the  cankered  regions  of 
the  branches  or  stem  and  thick  clumps  of  suckers  on  the  trunk  and 


DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES   OF  PLANTS       495 

branches,  or  at  the  base  of  the  tree,  are  evidences  that  the  trees  are 
attacked  by  the  chestnut  blight  fungus. 

The  cankers  on  smooth  bark  are  especially  marked,  and  with  a 
reddish-brown  color  in  contrast  with  the  healthy  bark  can  be  seen  for  a 
considerable  distance  (Fig.  171).  As  sunken,  or  swollen  diseased  areas 
of  the  bark,  they  occur  on  branches  of  all  sizes  and  generally  the  cankers 
are  ellipsoidal  with  the  long  axis  up  and  down  the  stem  (Fig.  171). 
The  cankered  areas  of  bark  become  covered  with  numerous  small 
pimples  (Fig.  172)  from  which  emerge  in  wet  weather  long  twisted 


Fig.  174. — Chestnut  blight  fungus,  iiMffoi/u'o  parasitica.  A,  Pustules  on  bark; 
B,  escape  of  pycnospores  as  gelatinous  cords;  C,  D,  magnified  views  of  the  cord-like 
masses  of  pycnospores.      {From  Gager  after  Murrill.) 


yellow  horns  of  a  gelatinous  nature  (Figs.  173  and  174).  As  the 
canker  ages  the  bark  splits  and  cracks,  and  in  a  year  or  two  it  peels 
off  from  the  tree  leaving  the  wood  exposed  to  the  weather  (Fig.  127). 
The  mycelium  forms  thick,  fan-Uke  mats  in  the  bark  and  cambium 
of  the  tree  and  it  spreads  both  longitudinally  and  circumferentially 
(Fig.  175)  until,  having  completed  its  growth  around  the  stem,  or 
branch,  and  killed  the  cambium  and  bark,  the  part  of  the  tree  above 
the  girdled  portion  succumbs  and  the  next  year  leafless  branches 
show  the  irreparable  damage  done  to  the  tree  by  the  blight  fungus 
(Fig.  127). 


496  SPECIAL   PLANT   PATHOLOGY 


Fig.  175. — Fan-shaped  mycelium  of  chestnut  blight  fungus  (Endothia  parasitica) 
from  rough  bark  of  a  chestnut  tree.  (Photo  by  E.  T.  Kirk,  after  Anderson,  Bull.  5, 
Chestnut  Tree  Blight  Com.,  IQIS-) 


DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES   OF  PLANTS       497 

Morphology. — On  smooth  bark,  especially  in  summer,  the  outer  cork 
layer  is  raised  into  numerous  little  blisters,  with  slender,  yellow,  waxy 
twisted  horns  emerging  from  a  pore  in  their  apices.  A  section  across 
each  blister  reveals  a  somewhat  globose  pycnidium  surrounded  by  a 
scanty  loose  mass  of  whitish,  or  yellowish  hyphae,  which  merge  with 
the  tangled  hyphae  that  make  up  the  pycnidial  wall.  The  conidio- 
phores  arise  inside  the  pycnidium,  as  a  dense  brush-like  fungi  and  pro- 
ject into  the  fruit  cavity  (Figs.  174  and  176).  They  range  in  length 
from  20  to  40/1.  From  these  conidiophores,  spores  (pycnospores)  are 
abstricted,  and  as  the  cavity  is  filled  with  the  hyphal  stalks,  the  pyc- 
nospores are  forced  out  at  an  opening  in  the  top  of  the  pycnidium  in 
the  form  of  a  twisted  slimy  cord  (Figs.  173  and  174).  The  smooth 
hyaline  pycnospores  are  held  together  by  a  sticky  material  and  they 
measure  1.28  by  3.56/i  in  size,  and  are  oblong  cylindric  with  rounded 
ends  sometimes  slightly  curved.  Heald  and  Gardner^  find  that  the 
pycnospores  are  to  a  considerable  degree  resistant  to  desiccation  in 
soil  in  the  field  and  that  a  large  number  may  retain  their  viability 
during  a  period  of  2  to  13  days  of  dry  weather  (Fig.  177).  They 
found  that  with  indoor  desiccation  a  large  number  of  spores  survived 
two  months  and  that  in  5  out  of  12  samples  not  all  of  the  spores  had 
succumbed  after  three  months  of  drying.  The  longevity  limit  varies 
from  54  to  119  days,  the  average  being  81  days.  Studhalter  and  Rug- 
gles^  by  experimental  methods  obtained  some  interesting  results  as  to 
insects  as  carriers  of  the  chestnut  blight  fungus.  Tests  were  made 
with  twenty-one  ants  in  certain  laboratory  and  insectary  experiments 
in  which  they  had  been  permitted  to  run  over  chestnut  bark  bearing 

1  Heald,  F.  D.  and  Gardner,  M.  W.:  Longevity  of  Pycnospores  of  the  Chestnut 
Blight  Fungus  in  Soil.  Journal  Agricultural  Research  II:  67-75,  April  15,  1914. 
Additional  facts  in  the  life  history  of  the  chestnut  blight  fungus  are  presented 
in  the  following:  Heald,  F.  D.,  and  Walton,  R.  C:  The  Expulsion  of  the 
Ascospores  from  the  Perithecia  of  Endothia  Parasitica  (Murr.),  Amer.  Jour. 
Bot.,  1:449-521,  Dec,  1914;  Heald,  F.  D.,  and  Studhalter,  R.  A.:  Seasonal 
Duration  of  Ascospore  Expulsion  of  Endothia  parasitica.  Amer.  Journ.  Bot., 
2:  429-448,  Nov.,  1915;  Ibid.,  The  Effect  of  Continual  Desiccation  on  the  Expul- 
sion of  Ascospores  of  Endothia  Parasitica.  Mycologia,  7:  126-130;  Ibid.,  Lon- 
gevity of  Pycnospores  and  Ascospores  of  Endothia  Parasitica  under  Artificial 
Conditions.  Phytopath,  5:35-44;  Stevens,  Neil  E.  :  Some  Factors  Influencing 
the  Prevalence  of  Endothiagyrosa.    Bull.  Ton.  Bot.  Club,  44: 127-144,  Mch.,  191 7. 

2  Studhalter,  R.  A.  and  Ruggles,  A.  G.:  Penna.  Dept.  of  Forestry.  Bull.  12, 
April,  1915. 

32 


498  SPECIAL   PLANT   PATHOLOGY 

spore  horns  or  active  perithecial  pustules  of  Endothia  parasitica.  They 
found  that  five  of  the  twenty-one  ants  were  carrying  spores.  Tests 
with  other  insects  demonstrated  that  they  were  carrying  spores.  The 
number  of  viable  spores  carried  varied  from  74  to  336.960  per  insect, 
and  the  last  number  was  obtained  on  Leptostylus  Macula,  one  of  the 
beetles,  which  feeds  on  the  pustules  of  the  blight  fungus.  During 
these  experiments,  it  was  proved  that  the  spores  of  Endothia  parasitica 
were  easily  shaken  from  the  body  of  the  beetle  during  its  own  move- 
ments. Heald  and  Studhalter^  undertook  to  determine  whether  birds 
carried  the  spores.  They  found  on  birds  shot  on  blighted  chestnut 
trees  after  the  bill,  head,  tail,  feet  and  wings  of  each  bird  were  scrubbed 
with  a  brush  and  poured  plates  were  made  from  the  wash  water,  which 
was  retained  and  centrifuged  for  its  sediment,  that  in  the  case  of  the 
36  birds  tested,  19  were  found  to  be  carrying  the  spores  of  the  chestnut- 
blight  fungus.  The  viable  spores  carried  by  two  downy  woodpeckers 
numbered  757,074  and  642,341  respectively,  while  a  brown  creeper 
carried  254,019,  and  that  the  highest  positive  results  were  obtained 
from  birds  shot  two  to  four  days  after  a  period  of  considerable  rain- 
fall. Analyses  of  spore  traps  at  West  Chester  and  Martic  Forge^ 
showed  that  viable  pycnospores  of  the  chestnut  blight  fungus  were 
washed  down  the  trees  in  enormous  numbers  during  every  winter 
rain. 

The  mature  stromata  on  older  cankers  have  numerous  projecting 
papillae  on  the  surface.  The  black  speck  at  the  tip  of  each  papilla  is 
the  opening  of  a  perithecium,  which  is  a  bottle-shaped  depression  with 
a  long  neck-like,  black  canal  opening  at  the  surface.  There  are  com- 
monly fifteen  to  thirty  perithecia  in  a  stroma.  The  mature  perithecia 
(Fig.  176)  measure  about  350  to  400^1  in  diameter,  and  are  mostly 
spherical.  The  neck  is  usually  four  to  six  times  the  diameter  of  the 
perithecium  and  its  black  wall  is  composed  of  densely  interwoven, 
septate,  heavy-walled  hyphae  running  parallel  with  the  long  axis  of 
the  neck.  The  asci  are  clavate,  or  oblong,  and  contain  eight  ascospores 
imbedded  in  an  epiplasm.     The  ascospores  are  two  celled  and  measure 

1  Heald,  F.  D.  and  Stud  halter,  R.  A.:  Birds  as  Carriers  of  the  Chestnut  Blight 
Fungus.     Journal  of  Agricultural  Research  II:  405-422,  Sept.  21,  1914. 

2  Heald,  F.  D.  and  Gardner,  M.  W.:  The  Relative  Prevalence  of  Pycnospores 
and  Ascospores  of  the  Chestnut  Blight  Fungus  during  the  Winter.  Phytopathology 
3:  296-305,  December,  1913. 


DETAILED  ACCOUNT   OF  SPECIFIC  DISEASES   OF  PLANTS       499 

4.5  to  8.6/i  in  size  (Fig.  177).     The  walls  are  thicker  than  those  of  the 
pycnospores.     Expulsion  of  the  ascospores  is  dependent  upon  tempera- 


-^f 


■•^'^^:!d^>^ 


Fig.  176. — A,  Vertical  section  of  a  pycnidial  pustule.  The  filaments  lining  the 
cavity  produce  the  spores  that  ooze  out  as  "spore-horns;"  B,  vertical  section  of  a 
perithecial  pustule.  '  Several  of  the  perithecia  are  cut  so  as  to  show  the  fuUlengths 
of  the  necks  in  the  chestnut  blight  fungus  (Endoihia  parasitica).  (After  Heald, 
F.  D.,  Bull.  5,  Chestnut  Tree  Blight  Com.,  1913.) 

ture,  as  well  as  moisture.     There  was  no  expulsion  of  ascospores  under 
field  conditions  from  late  November  until  the  rain  of  March  21,  when 


500 


SPECIAL   PLANT   PATHOLOGY 


temperature  conditions  were  favorable.     Ascospores  were  not  expelled 
during  the  warm  winter  rains,  but  during  the  summer  rains  ascospores 


Fig.  177. — Spore-sacs  or  asci  with  eight  two-celled  ascospores  of  chestnut  blight 
fungus  (Endoihia  parasitica).  Below  diagram  showing  relative  size  of  pycnospores 
(left)  and  ascospores  (right).  (After  Heald,  F.  D.,  Bull.  5,  Chestnut  Tree  Blight 
Cojn.,  1913.) 


are  forcibly  expelled  in  large  numbers  from  the  perithecia  during  and 
after  each  warm  rain  in  case  the  amount  of  rain  is  sufficient  to  soak  up 


DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES   OF  PLANTS       501 


Fig.  178. — Photograph  showing  svtccessive  stages  in  the  germination  of  asco- 
spores  and  pycnospores  of  the  chestnut  blight  fungus  {Endolhia  parasitica).  Left, 
ascospore  series  from  8  to  22  hours  at  hourly  intervals;  right,  pycnospore  series  from 
8  to  22  hours,  taken  every  two  hours.  {After  photo  by  Wm,  Currie,  Bull.  5,  Penna. 
Chestnut  Tree  Blight  Com.,  1913.) 


502  SPECIAL   PLANT   PATHOLOGY 

the  pustules.^  All  of  the  experiments  point  to  air  and  wind  transport 
of  the  ascospores,  as  one  of  the  very  important  methods  of  dissemina- 
tion. Infection  is  by  means  of  wounds  produced  mechanically,  as  by 
insects  and  other  animals  (Fig.  178).  It  is  still  to  be  demonstrated  that 
the  parasite  can  enter  without  visible  breaks  in  the  bark.^  In  the 
control  of  this  disease  inspection  of  nursery  stock  should  be  made 
and  the  use  of  gas  tar  following  removal  of  diseased  branches. 

Leaf  Mildew  {Phyllactinia  corylea  (Pers.),  Korst). — The  under  leaf 
surfaces  of  the  chestnut  are  marked  frequently  by  irregular  patches 
of  mycelium,  which  constitute  the  mildew  fungus  (Fig.  53).  Typical 
haustoria  are  absent,  but  there  are  special  setalike  branches  which 
penetrate  the  leaf  tissues.  The  subglobose  perithecium  is  large  and 
is  garnished  with  rigid  needle-like  appendages  with  a  swollen  base 
(Fig.  53).  There  are  many  included  asci  usually  containing  two 
spores,  occasionally  three.  It  is  a  fungus  of  wide  geographic  distribu- 
tion throughout  the  temperate  regions  of  the  world. 

Clover   (Tri folium   spp.) 

Rust,  Uromyces  trifolii  (Hedw.),  Liv.- — The  common  clovers  of  our 
cultivated  fields,  such  as  the  red  clover,  alsike  clover,  white  clover,  and 
crimson  clover,  are  attacked  by  this  rust,  which  causes  serious  disease 
conditions  (Fig.  70,  E  and  F).  The  prevalence  of  the  disease  varies 
greatly  with  the  season.  The  clover  rust  fungus  is  autoecious,  all  of 
the  stages  being  found  on  the  same  host  plant.  All  of  the  stages 
occur  on  the  white  clover  (T.  repens).  In  general  the  spermagonia 
and  aecia  are  not  met  with  on  the  red  clover,  the  host  upon  which  the 
other  stages  are  perhaps  more  frequent.  The  mycelium  is  local  in  its 
occurrence  in  the  plant,  from  it  secia  and  spermagonia  arise  in  the  early 
spring,  or  at  almost  any  time  during  an  open  winter.  They  occur  on 
the  under  leaf  surfaces  and  on  the  leaf  stalk.  The  aeciospores  are  14 
to  23JU  in  diameter  and  germinate  readily  in  water. 

Heald,  F.  D.,  Gardner,  M.  W.  and  Studthalter,  R.  A.:  Air  and  Wind 
Dissemination  of  Ascospores  of  the  Chestnut  Blight  Fungus.  ■  Journal  of  Agricul- 
tural Research  iii:  493-526,  March  25,  1916. 

'^  For  numerous  other  details  consult  Anderson,  P.  J.  and  Rankin,  W.  H.: 
Endothia  Canker  of  Chestnut.  Bull.  347,  Cornell  University  Agricultural  Experi- 
ment Station,  June,  1914. 


DETAILED  ACCOUNT   OF   SPECIFIC  DISEASES   OF  PLANTS       503 

The  urediniospores  are  about  22-26/x  by  18-20/x,  and  repeated 
crops  of  these  may  be  produced.  The  teliospores  are  formed  in  sori 
with  the  urediniospores,  as  the  season  advances.  They  are  one- 
celled,  thick  walled  and  measure  20-35/x  by  15-22^-  The  teliospores 
germinate  in  the  ordinary  way  by  the  formation  of  a  four-celled 
basidium  each  producing  a  basidiospore.  No  satisfactory  method 
of  controlling  clover  rust  is  known. 

Coffee  (Cojfea  arabica,  L.) 

Leaf-spot  {Cercospora  caffeicola,  B.  &  €.).■ — The  leaves  and  fruits 
of  coffee  plants  in  the  Dutch  East  Indies,  Mexico,  Cuba,  Jamaica, 
Trinidad  and  Brazil  are  attacked  by  the  leaf-spot  fungus,  which  causes 
large  blotches  at  first  visible  only  on  the  upper  leaf  surface.  The  spots 
are  dark  brown  at  first,  later  becoming  grayish  above  and  clear  below. 
The  center  of  these  blotches  die  and  here  the  spores  are  borne.  The 
disease  causes  the  leaves  to  fall,  thus  reducing  the  vigor  of  the  plant 
and  preventing  the  proper  maturing  of  the  coffee  berries.  Infected 
berries  fall  before  ripening. 

Rust  {Hemileia  vastatrix,  Berkeley  &  Broome) .^ — The  coffee  rust  is 
widely  spread  through  the  coffee-growing  regions  of  the  old  world, 
and  it  has  been  reported  from  the  American  tropics,  but  there  is  some 
uncertainty  about  reports.  It  is  the  most  destructive  disease  of  the 
coffee  plant  and  American  coffee  growers  should  be  on  the  lookout 
for  it. 

Orange-red  spots  appear  on  the  leaves,  which  finally  wither  and  drop, 
and  frequently  parts  or  whole  plants  die,  especially  during  the  rainy 
season,  when  the  red  spots  increase  in  number.  The  spots  appear  as 
shghtly  transparent  discolorations,  which  are  not  easily  observed  until 
the  leaf  is  held  up  to  the  Hght.  An  older  spot  is  yellow  in  color  and  then 
a  bright  orange  color.  They  vary  in  size,  but  are  usually  circular  in 
outhne,  and  increase  in  number  during  June  and  July,  when  the  disease 
reaches  its  culmination,  if  the  weather  conditions  are  favorable.  The 
spores  are  produced  in  great  abundance  in  the  orange-red  spots  and  on 
being  set  free  are  carried  by  the  wind  and  insects  to  other  coffee  plants 
on  the  leaves  of  which  they  germinate  sending  a  germ-tube  into  the 
leaf  through  the  stomata.  The  urediniospores  35  to  40/x  by  25  to  28ju 
are  single,  usually  egg-shaped,  provided  with  a  papilla  and  without 


504  SPECIAL   PLANT   PATHOLOGY 

germ-pores.     The  teliospores  are  unicellular.     As  a  remedial  measure 
the  use  of  tobacco  water  or  Bordeaux  mixture  is  recommended. 


Corn  (Zea  mays,  L.) 

Dry-rot  {Diplodia  zees  (Schw.),  Lev.). — The  dry  rot  fungus  attacks 
the  dry  ears  of  corn  soon  after  silking  and  does  not  usually  manifest 
itself  until  husking  time,  when  the  kernels  are  found  to  be  covered  with 
a  whitish  mycelial  growth,  which  dips  down  between  the  individual 
grains  of  corn.  The  grains  so  attacked  become  shrunken,  loosely 
attached  to  the  cob,  lighter  in  weight,  darker  in  color,  and  more  brittle 
than  the  healthy  grains.  Pycnidia  may  be  found  imbedded  in  the 
mycelium,  especially  between  the  kernels.  In  the  open  field,  these 
pycnidia  may  be  formed  in  such  numbers  as  to  impart  a  black  color 
to  the  grains  of  corn.  Of  course  the  feeding  value  of  the  corn  is  gone 
and  some  physicians  even  ascribe  pellagra  to  the  use  of  such  moldy 
corn.  When  the  fungus  attacks  the  stalks,  it  forms  small  dark  specks 
under  the  epidermis  near  the  nodes  and  even  on  three-year-old  stalks 
pycnidia  have  been  found.  Infection  takes  place  through  the  roots 
and  the  fungus  which  enters  in  this  way  finally  reaches  the  stem.  Ear 
infection  may  also  occur  through  the  silk  by  wind-blown  spores  which 
come  from  old  diseased  stalks  left  in  the  field,  so  that  by  destroying 
the  corn  trash  the  disease  can  be  controlled  to  some  extent.  Rotation 
of  crops  is  probably  more  efficacious. 

Smut  {Ustilago  zem  (Beckm.),  linger). — The  smut  boils  of  Indian 
corn,  or  maize,  are  found  not  only  on  the  ears  as  with  most  smuts,  but 
also  on  the  husks,  on  the  tassels  of  male  flowers,  on  the  leaves,  and  even 
on  the  stem  (Figs.  179  and  180).  The  attack  first  begins  on  any  young 
and  tender  part  of  the  plant.  If  the  leaves  are  the  part  attacked,  they 
assume  a  pale  yellow  hue  and  are  puckered  with  smaller,  or  larger 
bladder-like  swellings.  The  swellings  are  made  up  of  masses  of  the 
hyphae  of  the  smut  fungus  and  their  surface  is  covered  with  a  smooth 
skin-like  covering.  Later  the  hyphae  divide  up  into  innumerable 
rounded  cells,  which  develop  into  the  smut  spores,  or  chlamydospores. 
Finally,  the  silvery-white  skin  having  been  more  and  more  stretched 
bursts,  and  the  black  chlamydospores  are  set  free,  as  a  powdery 
mass.  The  echinulate  chlamydospores  measures  8  to  12/i,  and  they 
readily  germinate  in  manure-water  giving  rise  to  a  four-celled  basidium, 


DETAILED  ACCOUNT  OF   SPECIFIC  DISEASES   OF  PLANTS       505 

each  cell  of  which  produces  a  basidiospore.     Infection  of  the  nascent 
tissue  at  any  part  of  the  growing  corn  plant  is  accomplished  by  the 


Fig.  179. — Smut  boil  of  UsUlago  zea  on  ear  of  corn,  developed  from  one  infected 
kernel.  {After  Jackson,  F.  S.,  Bull.  83,  Del.  Coll.  Agric.  Exper.  Slat.,  December, 
1908.) 


basidiospores  and  not  by  the  chlamydospores  (Fig.  181).     Wet  weather 
is  essentia]  for  the  growth  of  the  corn  and  the  smut  also. 


5o6 


SPECIAL   PLANT   PATHOLOGY 


The  disease  may  be  controlled  by  removing  the  smutted  plants 
from  the  field  and  destroying  them  and  also  by  a  rotation  of  crops. 


Fig.   i8o. — Corn  smut  on  tassels  of  sweet  corn.      (After  Jackson,  F.  S.,  Bull.  83,  Del. 
Coll.  Agric.  Exper.  Slat.,  December,  1908.) 


As  the  fungus  may  infect  the  adult  plant,  the  treatment  of  the  seed 
corn  with  fungicides  has  been  unsuccessful.  Rotation  of  crops  also 
assists  in  keeping  smut  in  check. 


DETAILED  ACCOUNT  OF  SPJOCli'lC  DISEASES   OF  PLANTS       507 

Wilt  (Fseudomouas  SkwaHl,  Smith). — This  is  a  specific  communi- 
cable disease  of  sweet  corn  and  other  races  of  maize,  caused  by  a  yellow, 
polar-flagellate  organism  discovered  in  1895  by  F.  C.  Stewart.  The 
disease  has  been  found  on  Long  Island,  in  New  Jersey,  Washington, 
D.  C,  Maryland,  Michigan,  Virginia  and  West  Virginia.  One  of  the 
first  signs  of  the  disease  in  well-grown  plants  is  the  whitening  (drying 


Fig.  181. — Germination  of  the  chlamydospores  of  corn  smut  (Ustilago  zece);  i. 
Various  stages  in  germination  from  corn  3  days  after  being  placed  in  water;  2,  spores 
germinated  in  contact  with  air;  3,  several  days  after  spores  were  placed  in  1/20  per 
cent,  acetic  acid,  formation  of  infection  threads,  a.  Spores;  h,  propiycelia;  c,  basidio- 
spores;  d,  infection  threads;  e,  detached  pieces  of  mycelia.  {After  Bull.  57,  Univ. 
III.  Agric.  Exper.  Stat.,  March,  1900.) 

out)  of  the  male  inflorescence.  The  leaves  then  dry  out  and  the  plant 
is  dwarfed,  later  the  stem  dries.  If  the  leaves  or  the  stem  be  chosen  and 
broken  across,  sHmy  yellow  contents  ooze  out.  A  cross-section  of 
the  stem  shows  that  the  organism  fills  the  vessels  of  the  host  plant  and 
the  wilting  is  due  to  the  stoppage  of  the  water  suppHes  by  the  trachei'd 
plugging. 


508  SPECIAL   PLANT   PATHOLOGY 

The  greatest  pains  should  be  taken  to  secure  only  sound  seed  corn, 
but  in  the  present  indififerent  state  of  the  seed-trade,  even  the  best 
should  be  treated  with  mercuric  chloride  before  planting.  On  fields 
subject  to  the  disease,  only  resistant  varieties  should  be  planted. 
Manure  containing  corn  stalks  from  diseased  fields,  or  gathered  from 
animals  pastured  in  such  fields,  should  never  be  used  on  land  designed 
for  corn.^ 

Cotton  (Gossypium  sp.) 

Boll  Anthracnose  (Glomerella  gossypii  (Southw.)  Edg.)  (=  Colleto- 
trichum  gossypii,  Southw.),- — The  same  fungus  causes  an  anthracnose 
of  stem  and  boll  of  the  cotton  plant,  especially  in  the  Gulf  states.  The 
disease  is  more  important  when  it  attacks  the  boll,  or  the  seedlings. 
The  ^bolls  lose  their  green  color  and  become  dull  red,  or  bronzed. 
If  the  boll  is  nearly-  mature  when  attacked,  it  may  mature  and 
open  in  the  usual  manner,  but  if  attacked  early,  it  may  cause  a  prema- 
ture dying  of  the  carpels  and  an  unequal  growth  of  the  boll,  which  is 
liable  to  crack  open  and  expose  the  immature  lint  to  the  action  of  the 
weather.  The  first  evidence  of  the  disease  is  a  minute  reddish  spot, 
which  later  becomes  black  in  the  center  and  depressed  with  a  reddish 
border,  and  these  spots  may  run  together. 

Two  types  of  conidiophores  break  out  from  the  stroma  within  the 
tissues.  Some  of  the  conidiophores  are  hyaline  and  abstrict  conidio- 
spores  that  measure  4.5  to  7^1  by  15  to  20/x,  while  other  conidiophores  in 
the  form  of  setae  arise  from  the  dark  colored  cells  of  the  stroma.  The 
setse  are  clustered  and  bear  ovate,  basally  pointed  spores.  Spores  and 
setae  together  form  an  acervulus.  The  spores  germinate  readily  and 
produce  a  myceUum  which  grows  vigorously  in  culture,  is  hyahne, 
flexuous  and  abundantly  septate  and  it  may  give  rise  to  appressoria. 

Proper  remedial  measures  have  not  been  discovered,  and  a  field  of 
experimentation  is  opened  up  along  these  lines.  Use  resistant 
varieties. 

Rust  (Uredo  gossypii,  Lager.). — This  is  the  uredo  stage  of  Kuehneola 
gossypii  (Lagerh.)  Arth.  which  occurs  on  the  cotton  plant  in  Cuba, 
Puerto  Rico,  Florida  and  Guiana,     ^cia  are  wanting  in  the  life  cycle, 

1  Smith,  Erwin  F. :  Bacteria  in  Relation  to  Plant  Diseases,  Volume  III:  89-150, 
1914,^ where  full  details  of  the  experimental  study  of  the  disease  and  the  causal 
organism  will  be  found. 


DETAILED  ACCOUNT   OF   SPECIFIC  DISEASES   OF  PLANTS       509 

while  the  other  spore  forms  are  represented  by  urediniospores  and 
teliospores.  All  parts  of  the  green  cotton  plant  may  be  rusted, 
spreading  to  the  new  leaves  as  they  are  formed.  Small  rounded,  or 
angular,  purplish-brown  spots  appear  on  the  upper  leaf  surface  and  the 
urediniospores  are  borne  in  pustules  just  beneath  the  epidermis  on  the 
under  leaf  surface,  which  finally  ruptures  and  sets  them  free.  The 
varieties  of  cotton  grown  in  the  Southern  United  States  are  partially 
immune,  while  the  tropic  varieties  are  more  susceptible.  It  is  rec- 
ommended that  the  cotton  grower  destroys  all  rubbish  in  his  fields 
and  adopts  a  system  of  field  culture  in  which  only  vigorous  plants  will 
be  obtained. 

Cranberry  {Vaccinium  macrocarpon,  Ait.) 

Gall  (Synchytrium  vaccina,  Thomas)  (Fig.  230). — The  fungus  which 
causes  cranberry  gall  is  a  very  much  reduced  phycomycetous  one,  which 
attacks  the  young  stems  and  leaves,  as  well  as  flowers  and  fruit  of  the 
cranberry.  It  also  lives  on  other  ericaceous  plants.  The  galls  are 
small  in  size,  reddish  in  color  and  are  produced  in  great  numbers  on  the 
parts  affected.  The  fungous  body  is  much  reduced,  consisting  of  a 
single  cell  which  becomes  a  zoosporangium.  The  presence  of  this 
parasitic  cell  in  the  tissues  of  the  host  is  to  produce  a  small  gall.  Later 
the  zoosporangium  develops  a  mass  of  swarm  spores,  or  zoospores, 
which  escape  into  the  water.  Infection,  therefore,  probably  takes 
place  when  water  is  abundant. 

Scald  {Guignardia  vaccinii  Shear). ^ — The  scald  fungus  (Figs.  182 
and  183)  may  attack  the  very  young  fruit  and  even  the  flowers  of  the 
cranberry  and  annually  does  considerable  damage  to  the  growing  crop, 
as  the  annual  loss  has  been  estimated  at  $200,000.  The  pycnidia 
are  usually  found  upon  such  parts.  The  berries  are  characterized  by 
watery  spots,  which  may  remain  small  under  certain  conditions,  while 
under  others  it  spreads  quickly,  often  concentrically  until  the  whole 
berry  becomes  soft.  The  leaves  are  also  spotted  with  irregular  brown 
spots  within  which  the  pycnidia  are  found. 

The  pycnidial  stage  is  a  characteristic  Phoma,  or  Phyllosticta, 
measuring  100  to  i20)u  in  diameter.  These  are  scattered  over  the 
affected  surface  and  abundant  hyaline,  obovoid  pycnospores  are  formed, 

1  Shear,  C.  L.:  Cranberry  Diseases.  U.  S.  Bureau  of  Plant  Industry.  Bull, 
no:  1-64,  1907. 


5IO 


SPECIAL  PLANT   PATHOLOGY 


Fig     182. — Cranberry  scald  {Guignardia  vaccinii  Shear).      {After  Shear;  Bull,  no, 
U.  S.  Bureau  Plant  Industry,  pi.  i,  1907.) 


DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES  OF  PLANTS       51I 


Fig.  183. — Details  of  cranberry  scald  fungus  (Guignardia  vaccinii).  i,  A  cran- 
berry leaf,  showing  pycnidia  of  Guignardia  vaccinii  thickly  scattered  over  the  under 
surface;  a,  a  cranberry  blossom  blasted  by  Guignardia  vaccinii,  showing  pycnidia  on 
calyx,  corolla,  and  pedicel;  b,  a  blasted  fruit,  showing  pycnidia.  2,  A  vertical  section 
of  a  single  pycnidium  of  Guignardia  vaccinii  from  a  cranberry  leaf,  showing  pycno- 
spores  in  various  stages  of  development.  3.  An  immature  pycnospore  of  the  same 
fungus,  showing  the  partially  formed  appendage;  a,  the  same,  showing  a  little  later 
stage  of  development;  h  and  c,  fully  developed  pycnospores  and  appendages.  4,  5, 
6,  7,  8,  and  9,  Various  stages  in  the  germination  and  growth  of  pycnospores  oiGuig- 
nardia  vaccinii  grown  in  weak  sugar  solution;  4,  5,  6,  and  7,  72  hours  after  sowing; 
8  and  9,  86  hours  after  sowing.  10,  A  vertical  section  of  a  perithecium  of  Guignardia 
vaccinii,  showing  asci,  from  a  cranberry  leaf  collected  in  New  Jersey.  11,  Three 
asci,  with  ascospores  showing  variations  in  length  of  the  stipe  and  the  arrangement 
of  the  spores;  a  and  b,  from  perithecia  on  a  leaf;  c,  from  a  pure  culture.      12,  A  fresh, 


512  SPECIAL   PLANT    PATHOLOGY 

which  measure  10.5  to  13. 5m  by  5  to  6ju.  The  ascigeral  stage  is  less  com- 
mon. The  perithecium  has  a  rather  dense  wall  inclosing  a  number  of 
clavate  asci,  which  are  60  to  80^1  long  (Fig.  183).  The  ascospores  are 
hyaline,  elliptic  to  sub-rhomboidal  in  form  with  granular  contents. 
The  fungus  has  been  grown  successfully  in  artificial  culture  media,  but 
after  a  few  generations,  it  seems  to  lose  in  vitality. 

Preventative  measures  consist  in  an  occasional  renovation  of  the 
bag  and  in  the  proper  regulation  of  the  water  supply.  Spraying  at 
least  six  times  with  Bordeaux  mixture  (5-5-50)  is  used  with  success; 
especially,  if  adhesive  substances  (4  pounds  resin  fish  oil  soap)  are 
added  to  the  mixture. 

Grape  {Vitis  spp.) 

Black-rot  (Guignardia  Bidwellii  (Ell.)  V.  &  R.). — Wherever  the 
grape  is  grown  this  American  fungus  is  a  constant  menace  to  the  suc- 
cessful prosecution  of  the  industry.  It  attacks  not  only  the  fruits,  but 
also  the  leaves,  fruit  pedicels  and  stems.  The  disease,  which  is  most 
important  on  the  berries  (.Fig.  184),  begins  as  a  small  circular  brown  spot 
which  enlarges  until  it  is  5  to  10  mm.  in  diameter,  when  the  center  of  the 
spot  will  be  found  to  show  a  few  black  pimples  which  are  the  openings 
of  the  pycnidia,  which  have  now  appeared  beneath  the  skin.  The 
spots  become  darker  in  color  and  spread  until  more  than  one-half  of 
the  fruit  surface  is  involved,  when  the  fruit  begins  to  lose  its  spheric 
contour  and  to  shrivel,  persistently  hanging  on  the  vine  sometimes 
throughout  the  season.  Nearly  all  of  the  dark  colored  grapes  are 
susceptible,  such  as  the  universally  grown  Concord,  while  some  light 
colored  varieties  are  more  resistant.  The  Scuppernong  is  apparently 
entirely  resistant. 

As  with  many  of  the  fungi  which  attack  our  cultivated  plants,  the 
different  stages  were  known  before  the  complete  life  cycles  were  de- 
termined and  therefore,  these  stages  received  scientific  names,  which 
are  relegated  to  synonymy,  when  the  life  history  becomes   known 

mature  ascospore,  showing  the  usual  condition,  in  which  the  protoplasm  is  very 
coarsely  granular.  13,  An  old  ascospore  from  a  dried  specimen,  having  its  contents 
homogeneous.  14,  a,  A  portion  of  the  coarse  brown  mycelium  from  the  interior  of 
a  scalded  berry,  from  which  a  culture  was  made  December  23,  producing  pycnidia 
and  ascogenous  perithecia  of  Guignardia  vaccinii;  b,  a  portion  of  younger,  lighter 
colored  hyph^  from  the  same  berry.  (After  Shear,  C.  L.,  Bull,  no,  U.  S.  Bureau  of 
Plant  Industry,  1907.) 


DETAILED   ACCOUNT   OF   SPECIFIC   DISEASES    OF   PLANTS       513 


thoroughly.  So  it  has  been  with  tlie  black-rot  fungus.  The  pycnidial 
stage  on  the  grape  leaves  (Fig.  185)  was  called  PhyUosticla  lahrusca, 
while  on  the  fruit  it  was  called  Phoma  uvicola.  These  have  been 
determined  to  be  merely  stages  of  one  and  the  same  fungus,  Guignardia 
Bidwellii.  The  mycelium  of  the  black-rot  fungus  is  never  abundant  in 
the  outer  portions  of  the  berries  where  it  is  found.  Here  a  stromatic 
mass  of  hyphse  arises  beneath  the  grape  skin  and  develop  the  pycnidia, 
which  are  broadly  elliptic,  thick-walled  and 
beakless  depressions  from  the  inner  walls  of 
which  the  pycnidiophores  arise  which  abstrict 
off  the  ovate  to  elliptic  pycnidiospores  (pycno- 
spores)  8  to  1 0/1  by  7  to  S^t.  These  are  pushed 
out  in  twisted  masses  and  can  germinate  im- 
mediately. 

Spermagonia-like  pycnidia  of  smaller  size 
are  also  found.  These  produce  filiform  con- 
idiophores,  which  cut  off  minute,  slightly 
curved  microconidia.  The  ascigeral'  stage, 
discovered  in  1880,  may  be  had  on  fruit, 
which  has  been  covered  with  grass  and  leaves 
in  the  dried  up  state.  The  perithecia  are 
globose  and  bear  broadly  clavate  asci  con- 
taining eight  unicellular  ascospores,  measur- 
ing 12  to  i7Aiby  4.5  to  5M. 

The  black-rot  grape  disease  can  be  con- 
trolled by  Bordeaux  mixture  (4-4-50).  The 
first  application  should  be  made  in  the  spring, 

just  as  the  buds   begin  to  swell,  followed  by    Spring   Harbor,   L.    I.,   July 

■'  c  ■>  J     20,  1915. 

a  second  spraying,  as  the  buds  unfold.     Sub- 
sequent sprayings,  always  before  rain  storms,  to  the  number  of  five 
or  six,  should  be  made  two  weeks  apart  during  the  season.     After 
July  20  use' 4-2-50  Bordeaux,  or  ammoniacal  copper  carbonate. 

Downy  Mildew  (Flasmopora  viticola  (B.  &  C.)  Berl.  &  DeTon). — 
The  consensus  of  opinion  among  mycologists  is  that  the  downy  mildew 
fungus  is  of  American  origin,  and  it  is  now  widely  spread  in  Europe  and 
eastern  North  America,  where  it  probably  did  not  originate.  It  has 
been  noted  on  practically  every  variety  of  cultivated  and  wild  grapes, 
and  it  attacks  stems,  leaves  and  berries.  Usually  it  confines  its  attack 
3.5 


Fig.  184. — Black-rot 
fungus,  Guignardia  Bidwellii, 
attacking  green  grapes.  Cold 


514 


SPECIAL   PLANT   PATHOLOCxY 


to  the  grape"  leaves  (Fig.  i86),  where  it  produces  under  ordinary 
conditions  spots  of  mildew,  especially  on  the  lower  leaf  surface.  In 
bad  cases,  the  whole  lower  leaf  surface  may  be  covered  with  the  downy, 
or  cottony  mass  of  hyphae  which  gives  the  fungus  its  common  name. 
The  parasitic  hyphse  live  in  the  intercellular  spaces  of  the  host  and 
send  into  the  host  cells  small  knob-like  haustoria.  The  presence  of 
the  mycelium  seriously  interferes  with  the  normal  physiologic  activity 
of  the  host.  In  light  cases,  the  areas  of  upper  leaf  surface  immediately 
overlying  the  hyphse  turn  brown  in  the  form  of  angular  spots.     Through 


Fig.  185. — Black-rot  fungus  {Guignardia  Bidwellii).  a.  Portion  of  an  affected 
grape  showing  pustules;  b,  section  of  pustule  (pycnium)  showing  pycnospores;  c, 
ascus  with  ascospores;  d,  ascospores.  {After  Quaintance,  A.  L.,  and  Shear,  C.  L., 
U.  S.  Farmers'  Bull.  284,  1907-) 

the  stomata  emerge  stifif  projecting  conidiophores  which  form  short 
stub-Hke  branches  from  which  fall  ellipsoidal  conidiospores.  These 
conidiospores  are  virtually  zoosporangia  for  their  protoplasmic  con- 
tents divide  into  a  number  of  biciliate  zoospores  which  escape  and 
swim  about  in  the  rain  water  which  covers  the  leaf  or  stem,  or  are  washed 
down,  or  splashed  from  plant  to  plant  during  a  dashing  rain  storm. 
When  the  fungus  appears  on  the  fruit,  it  has  been  called  gray  rot,  and 
occasionally,  the  berry  may  be  completely  covered  with  a  downy  mass 
of  hyphae. 


DETAILED  ACCOUNT  OF  SPECIFIC  DISEASES   OF  PLANTS       515 

The  oogonia  and  antheridia  are  not  so  common  as  the  conidiospores. 
If  the  shriveled  parts  of  the  leaves  are  examined  in  September,  the 


Fig.    186. — Grape  leaf  attacked  by  mildew,  Plasnwpara  vilicola,  Cold  Spring  Harbor, 
L.  I.,  Aug.  2,  1915. 

oogonia  will  be  found  as  spheric  organs  attached  to  the  intercellular 
hyphae  by  a  short  stalk.  One  or  several  filamentous  curved  antheridia 
are  formed  near  the  oogonia  to  the  surface  of  which  they  become  ap- 


5l6  SPECIAL   PLANT    PATHOLOGY 

plied.  A  germ  tube  is  formed  through  which  the  antheridial  con- 
tents pass  over  into  the  oogonium.  A  single  large  central  egg-cell,  or 
oosphere,  becomes  differentiated  in  the  protoplasm  of  the  oogonium; 
this  contains  a  single  nucleus  in  a  central  position,  while  the  remaining 
nuclei  pass  into  the  peripheral  layer  of  protoplasm  (periplasm).  A 
single  male  nucleus  passes  through  the  antheridial  beak  into  the 
oosphere,  which  becomes  surrounded  by  a  cell  wall.  Nuclear  fusion 
now  takes  place  and  the  oosphere  becomes  an  oospore  with  a  single 
central  nucleus.     The  oospores  are  about  30/x  in  diameter. 

Bordeaux  mixture  is  the  most  important  fungicide  used  in  combating 
the  downy  mildew  disease.     It  is  applied  as  in  black-rot. 


CHAPTER  XXXV 

DETAILED  ACCOUNT  OF  SPECIFIC  PLANT  DISEASES 
(CONTINUED) 

Hemlock   (Tsiiga  canadensis  Carr) 

Heart-rot  (Polyporus  borealis  (Wahl.),  Fr.). — This  bracket  fungus  is 
distributed  widely  in  North  Temperate  regions.  As  a  wound  para- 
site, it  occurs  on  hemlocks,  pines  and  spruces,  entering  these  trees 
through  the  stubs  formed  by  the  breaking  ofif  of  branches.  The 
mycelium  gradually  grows  into  the  heart  of  the  trees  and  from  there 
downward  into  the  roots  and  upward  into  the  tops.  It  advances  in 
definite  directions  through  the  wood  in  the  form  of  cords,  or  strands, 
which  run  radially,  or  tangentially,  in  the  channels  dissolved  by  the 
action  of  the  enzyme,  which  is  formed  by  the  living  hyphae.  The 
wood  shrinks  and  the  mycelial  strands  begin  to  dry  up,  and  the  wood 
is  separated  into  cuboidal  blocks  marked  off  by  the  channels  formed 
by  enzyme  action.  If  the  mycelium  attacks  the  cambium,  the  trees 
die.  The  bracket-like  fruit  bodies  are  soft  and  spongy  and  last  only  a 
season.  They  are,  according  to  Atkinson,  lo  to  20  cm.  (4  to  8  inches) 
by  6  to  15  cm.  broad.  Several  of  these  sporophores  may  be  joined 
together.  The  upper  surface  is  rough,  shaggy  and  has  a  sodden  ap- 
pearance. The  pores  on  the  under  side  are  quite  regular  with  rounded 
openings  in  some  specimens,  or  irregular,  elongated  and  sinuous  in  other 
samples. 

Hollyhock  (AlihcBa  rosea  Cav.)  (Fig.  187) 

Rust  {Puccinia  malvacearimi,  Mont.).' — This  fungus  was  introduced 
into  France  about  1868  from  Chili,  where  it  is  native,  and  in  the 
summer  of  191 5,  the  writer  found  it  very  destructive  to  the  hollyhocks 
in  the  gardens  on  the  Island  of  Nantucket  off  the  southern  coast  of  New 
England.  It  spread  rapidly  over  Europe  and  came  to  the  United 
States  in  1886  upon  infected  seed.  The  leaves  are  spotted  with  the 
yellowish-brown  sori  slightly  raised  above  the  leaf  surface  (Fig.  72),  or 
they  are  found  on  the  stem  in  the  form  of  small  wart-like  elevations. 
The  leaves  dry  up,  as  if  blighted,  and  during  August  of  1915  on  Nan- 

517 


5j8 


SPECIAL   PLANT   PATHOLOGY 


Fig.  187. — Hollyhock  rust,  Puccinia  malvacearum.  i,  Typic  mature  telio- 
spore;  2-6,  different  stages  in  growth  of  promycelium  (basidium);  7,  forked  promy- 
celium;  8,  basidium  dividing  into  4  cells;  9,  basidium  resembling  a  germ  tube;  10-12, 
cells  breaking  apart;  13-16,  germination  of  promycelial  cells;  17,  empty  cell;  18, 
mature  basidiospores;  19,  20,  same  in  germination;  25,  26,  formation  of  chlamydo- 
spore-Hke  bodies  in  old  promycelia.  {After  Taubenhaus,  J.  J.:  Phytopath.  I,  April, 
1911.) 


DETAILED    ACCOUNT    OF    SPECIFIC   PLANT   DISEASES  519 

tucket  only  a  few  host  leaves  were  left  on  a  row  of  garden  hollyhocks, 
all  of  the  other  leaves  having  fallen  off.  The  sori  consist  of  light- 
colored  teliospores  which  are  two-celled  and  measure  17  to  241J,  by  35  to 
63M  (Fig.  187). 

Bordeaux  mixture  (4-3-50)  has  been  found  efficient,  as  a  spray,  in 
controlling  the  hollyhock  rust.  Others  recommend  sponging  the  dis- 
eased parts  with  permanganate  of  potash,  two  tablespoonfuls  of 
saturated  solution  diluted  with  one  quart  of  water. 

Larch  (Larix  spp.) 

Canker  {Dasyscypha  Willkommii,  Hartig). — The  life  history  of  this 
destructive  fungus  of  larch  trees  has  been  studied  by  German  plant 
pathologists,  so  that  it  is  pretty  well  known.  In  the  moist,  marsh 
meadows  in  the  mountains  of  Europe  where  the  larch  has  been  planted 
in  pure  forests,  the  fungus  has  been  frequent  in  past  years.  The 
mycelium  attacks  the  bast  elements  of  the  stem  and  its  insidious  char- 
acter is  manifested  in  the  death  of  the  bark,  which  peels  off.  Pro- 
nounced cankers  soon  develop  and  the  fungus  lives  perennially  in  the 
tree  spreading  rapidly  when  the  larch  tree  is  comparatively  inactive, 
viz.,  autumn  and  winter.  The  diseased  area,  represented  by  wounded 
tissue,  may  heal  over  during  the  growing  season,  but  when  the  fungus 
regains  its  activity  the  disease  progresses  until  the  branch  is  com- 
pletely girdled  and  its  terminal  part  dies. 

Creamy  white  stromatic  tufts  appear,  where  the  bark  has  been  killed 
and  on  this  superficial  mycelium  minute  conidiophores  arise,  which 
bear  simple  hyaline  conidiospores.  As  these  probably  do  not  germinate 
they  have  no  influence  in  the  spread  of  the  canker.  Short-stalked 
apothecia  may  appear  on  the  canker  areas  later  in  the  year.  They 
are  somewhat  yellow  on  the  outer  surface  and  orange  within.  The 
cylindric  asci  (i20;u  by  gn)  bear  light  ovoidal,  unicellular  ascospores. 
Filiform  paraphyses  are  found  between  the  asci.  No  efficient  remedial 
measures  are  known. 

Dry-rot  (Trametes  pini  (Brot  Fr.). — This  fungus  is  very  common 
in  the  forests  of  New  England,  Canada  and  Newfoundland.  It  grows 
on  nearly  all  coniferous  trees;  white  pine,  red  spruce,  white  spruce, 
hemlock,  balsam  fir  and  larch  attacking  the  living  trees  after  they 
begin  to  form  heartwood.     In  the  tamarack,  or  larch,  the  decay  goes 


520  SPECIAL   PLANT   PATHOLOGY 

much  beyond  that  of  the  spruce  and  balsam  fir.  In  the  early  stages, 
according  to  von  Schrenk,  small  white  spots  appear,  which  occupy  the 
entire  width  of  an  annual  ring.  Two  or  more  of  these  spots  soon  join, 
at  first  in  a  longitudinal  direction,  then  laterally  also,  so  that  one  or 
more  rings  of  woods  are  transformed  to  cellulose.  The  rings  are  thus 
separated  from  adjoining  ones  so  that  a  series  of  easily  separable 
tangential  plates  are  formed.  The  line  of  separation  between  the 
rings  is  always  at  the  point  where  the  summer  wood  stops  and  the 
spring  wood  of  the  following  year  begins. 

The  progress  of  decay  is  marked  by  the  attack  of  more  and  more 
sound  wood  fibers  which  are  reduced  to  loose  fibers  of  cellulose  until  the 
wood  has  disappeared,  when  black  lines  appear,  scattered  irregularly. 
The  tangential  plates  become  ultimately  extremely  thin  and  they  then 
consist  of  the  resistant  summer  wood  cells  more  or  less  infiltrated  with 
resin.  The  whole  of  the  former  woody  cylinder  becomes  a  mass  of 
separate  fibers  which  can  be  pulled  out  individually. 

The  fruiting  organ  is  found  commonly  on  all  of  the  afi"ected  trees. 
It  is  readily  distinguished  from  allied  forms  by  the  light  red-brown 
color  of  the  hymenial  surface,  and  the  regular  small  round  pores.  The 
form  of  the  pileus  varies  greatly.  Sometimes  the  brackets  are  large 
on  the  larch,  lo  cm.  (4  inches)  in  width  laterally,  7  cm.  (2.8  inches)  from 
front  to  back,  and  5  cm.  (2  inches)  in  thickness,  and  are  formed  at  the 
ends  of  old  hard  stubs  and  at  scattered  points  on  the  bark.  Some- 
times sessile  sheets  are  formed  inside  of  the  brackets.  The  basidia, 
which  form  the  hymenial  surface  that  lines  the  pores,  are  smaller  at 
the  apex  and  form  from  slender,  spore-bearing  sterigmata.  The 
basidiospores  are  brown  at  maturity. 

Lemon  {Citrus  limonum,  Risso.) 

Brown-rot  {Pylhiacystis  citriophora,  R.  E.  Smith). — The  disease  is 
characterized  by  a  copious  exudation  of  gum  from  the  trunk  just  above 
the  bud  union.  A  certain  area  of  the  bark  surrounding  the  part  which 
shows  gummosis  dies,  becomes  hard  and  dry  without  any  evidence  of 
the  fungous  parasite.  It  appears  especially  destructive  on  the  fruits 
after  packing,  and  is  recognized  as  a  brownish,  or  purplish,  discolora- 
tion of  the  rind,  which  is  lighter  green  than  on  the  ripe  fruits.  It 
spreads  rapidly  from  fruit  to  fruit,  and  is  also  characterized  by  its 
peculiar  odor  and  the  presence  of  small  flies   attracted   to  it.     The 


DETAILED   ACCOUNT   OP    SPECIFIC   PLANT   DISEASES  521 

mycelium  penetrates  the  lemon  rind  and  consists  of  much-branched 
extensive  hyphae  of  irregular  diameter.  Conidiospores  which  repre- 
sent zoosporangia  appear  under  fayorable  conditions.  They  measure 
20  to  60  by  40H  to  gofx  and  are  lemon-shaped  with  a  pronounced  protu- 
berance at  the  apex.  Upon  opening  a  number  of  biciliate  zoospores 
are  liberated. 

Infection  of  the  fruit  usually  takes  place  in  the  orchard  and  also 
during  the  operation  of  washing  the  lemons  preparatory  to  packing 
them.  The  wash  water,  therefore,  should  be  treated  with  copper 
sulphate,  formalin,  or  potassium  permanganate.  In  using  formalin, 
il  is  made  up  in  one  part  to  ten  thousand  parts  of  water,  or  i  pint  to 
about  1200  gallons.  Where  the  cheaper  copper  sulphate  is  more 
available,  i  pound  should  be  dissolved  in  250  gallons  of  water. 

Sooty  Mold  (Meliola  Penzigi,  Sacc,  and  M.  camellice  (Catt.)  Sacc). — 
This  fungus  is  widely  distributed  in  those  districts  where  citrus  fruits 
are  grown.  It  is  most  injurious  to  the  orange,  but  occurs  on  the 
lemon  as  well,  appearing  on  both  leaves  and  fruits.  The  mycelium 
forms  a  sooty  black  covering  on  the  leaves,  twigs  and  fruits  and  is 
usually  associated  with  various  scale  insects  and  aphids,  which  exude 
a  honey  dew  upon  which  and  the  dead  bodies  of  the  scale  "insects  the 
fungus  feeds  as  a  saprophyte.  The  mycelium  consists  of  large  branched 
threads,  which  are  closely  septate,  and  the  branches  are  cemented 
together  to  form  a  false  stratum,  which  lives  purely  as  a  superficial 
saprophytic  growth  without  penetrating  into  the  tissues  of  the  citrus 
plant  on  which  it  is  found.  Certain  hyphal  branches  flatten  out  and 
probably  serve  as  appressoria.  The  reproductive  cells  are  of  various 
kinds,  such  as  stylospores  in  pustules,  pycnidia  with  pycnidiospores 
(pycnospores)  and  perithecia.  The  stylospores  arise  from  small 
conidiophores  within  peculiar,  elongate,  flask-shaped  structures.  The 
pycnidia  are'  small  and  scattered.  The  perithecia  are  spheric  and  in 
close  asci  with  eight  dark  elliptic,  three-  to  four-septate  spores. 

The  most  effective  substance  for  the  treatment  of  sooty  mold  has 
been  found  by  Webber  to  be  the  resin  wash.^     The  mixture  consists  of 

Resin 20  lb. 

Caustic  soda  (98  per  cent.) 4  lb. 

Fish  oil  crude 3  lb. 

Water  to  make 15  gal. 

1  DuGGAR,  B.  M.:  Fungous  Diseases  of  Plants:  215. 


522  SPECIAL   PLANT   PATHOLOGY 

Webber  prepares  the  mixture  as  follows:  Place  the  resin,  caustic 
soda  and  fish  oil  in  a  large  kettle,  pour  over  them  13  gallons  of  water, 
and  boil  until  the  resin  is  thoroughly  dissolved,  which  requires  from 
three  to  ten  minutes  after  boiling  has  commenced.  While  hot,  add 
enough  water  just  to  make  15  gallons.  It  is  advised  to  make  about 
two  sprayings  when  the  white  fly  (Aleyrodes)  is  in  the  larval  stage. 
In  Florida  winter  sprayings  are  important,  but  a  spraying  in  May  is 
also  often  desirable.  In  all  cases  dilute  the  stock  solution  with  9 
parts  of  water. 

Lettuce  (Ladtica  saliva,  L.) 

Drop  {Sclerotinia  libertiana  Fckl.). — This  is  one  of  the  most  disas- 
trous of  the  sclerotium-producing  fungi  to  garden  and  greenhouse 
plants,  being  widely  distributed  and  difficult  to  control.  It  attacks 
greenhouse  lettuces,  causing  at  first  flagging,  then  indications  of 
water-soaked  areas  over  the  stem  and  basal  part  of  leaves,  finally  fol- 
lowed by  the  collapse  of  the  whole  plant  into  a  formless  mass.  The 
mycelium  may  grow  on  the  surface  of  the  lettuce  leaves  and  black 
sclerotia  may  be  formed  there  commencing  as  white  condensations 
which  finally  turn  black.  Conidiospore  formation  is  not  certainly 
known  in  the  lettuce-drop  fungus.  Sclerotia,  however,  are  commonly 
formed  which  measure  3  cm.  in  length  and  these  are  formed  even  on 
artificial  culture  media.  The  apothecia  are  wineglass-shaped  with 
long  black  stalks.  The  asci  formed  on  the  upper  depressed  side  of  the 
apothecia  are  cylindric  and  measure  130  to  13 5^  by  8  to  lo^u,  while  the 
ascospores  are  small,  9  to  13/i  by  4  to  6.5/1. 

All  dead  and  diseased  lettuce  plants  should  be  destroyed  by  fire 
and  the  ground  where  they  grew  soaked  with  some  suitable  fungicide 
so  as  to  confine,  or  practically  exterminate  the  disease.  The  soil 
should  be  sterilized  with  steam  before  planting. 

Lilac  {Syringa  vulgaris,  L.) 

Powdery  Mildew  {Microsphcsra  alni  (Wallr.)  Wint.).— During  the 
summer  months  and  late  in  the  autumn,  the  upper  surface  of  the  leaves 
of  the  lilac  will  be  found  covered  with  a  whitish  mildew  which  consists 
of  interlacing  hyphae,  which  form  a  cobwebby,  superficial  growth. 
Short  haustoria  are  produced  which  grow  into  the   epidermal   cells. 


DETAILED    ACCOUNT   OF    SPECIFIC   PLANT   DISEASES  523 

The  mycelium  develops  upright  vertical  conidiophores  which  abstrict 
off  conidiospores  in  chains.  These  conidiospores  no  doubt  account 
for  the  rapid  spread  of  the  disease,  which  is  never  very  serious  to  the 
Hlac  shrubs,  but  no  doubt  to  some  extent  interferes  with  the  normal 
physiologic  processes  of  the  leaves.  Subsequently  perithecia  are 
formed  which  are  spheric  in  shape,  almost  jet  black  in  color,  and  which 
are  surrounded  by  a  circlet  of  hyphae  known  as  appendages,  which  are 
curved  or  dichotomously  hooked  at  the  extremities.  Each  perithecium 
produces  3  to  8  asci,  and  each  ascus  contains  4  to  8  relatively  small 
ascospores,  which  measure  18  to  23/x  by  10  to  12/x  (Fig.  54). 

Maple  (Acer  spp.) 

Decay  {Fomes  fomentarius  (L.  Fr.)  (Fig.  188). — The  sporophores 
of  this  fungus  are  hoof-shaped  and  appear  first  as  small  rounded  knobs 
on  the  surface  of  the  trunk,  or  at  branch  stubs.  The  upper  surface  is 
smooth  and  more  or  less  definitely  marked  by  concentric  ridges.  The 
older  fruit  bodies  owing  to  the  action  of  the  weather  are  uniformly 
gray  and  appear  as  if  powdered.  The  lower  surface  is  reddish-brown 
in  color  and  shows  numerous,  small  round  pores.  The  margin  of  the 
new  layer  is  grayish  white  and  very  soft  and  velvety.  The  sporo- 
phores are  found  usually  singly,  althoughby  proximity  of  two,  or  several, 
they  may  appear  grouped  together.  The  decay  produced  in  the  wood 
of  deciduous  trees  by  Fomes  fomentarius  begins  in  the  outer  alburnum 
immediately  beneath  the  barky  layers,  and  extends  inwardly,  until 
it  reaches  the  pith  of  the  tree.  The  rotten  wood  is  distinguished  by 
a  large  number  of  irregular  black  fines  outlining  areas  of  sound  wood. 
Wholly  decayed  wood  is  extremely  soft  and  spongy,  fight  yellow  and 
crumbles  into  numerous  separate  wood  fibers  when  rubbed.  The 
tinder  fungus,  Fomes  fomentarius,  is  found  in  the  deciduous  forests  of 
Michigan,  Minnesota,  New  England,  New  York,  Wisconsin  and  in 
other  states.  It  grows  rapidly  in  dead  wood  and  the  mycefium  will 
form  large  masses  if  the  infected  timber  is  kept  under  moist  conditions. 

Leaf-blotch  (Rhytisma  acerinum  (Pers.),  Fr.). — The  tar  spot  of  the 
maple  is  found  about  Philadelphia  usually  on  the  silver  maple  to  which 
it  does  slight  injury.  The  black  irregular  spots  are,  however,  alwavs  of 
interest  to  the  laymen  and  questions  are  asked  frequently  about  their 
cause.     The  spot  begins,  as  a  yellow  thickened  area,  when  the  maple 


524 


SPECIAL   PLANT   PATHOLOGY 


leaves  are  expanded  fully.  The  epidermis  is  pushed  up  by  short  conidio- 
phores  which  arise  from  a  hyphal  stroma  beneath.  These  conidio- 
phores  produce  unicellular,  curved  conidiospores  which  serve  to  dis- 
tribute the  fungus.     Formerly  this  stage  was  called  Melosmia.     Later 


r-^ 


Fig.  1 88. — Cross-section  of  branch  of  dead  beech  rotted  by  Fomcs  fomenlarius. 
(After  von  Schrenk,  Hermann,  Bull.  149,  U.  S.  Bureau  of  Plant  Industry,  pi.  viii, 
1909.) 


as  the  season  advances,  the  hyphae  become  massed  into  a  sclerotium- 
like  area  black  without,  but  white  within,  and  this  persists  after  the  fall 
of  the  leaf.  Sometime  the  next  spring,  there  arise  from  these  sclerotia 
complex  apothecia  often  1.5  cm.  broad,  which  break  through  at  irregular 


DETAILED    ACCOUNT    OF    SPECIFIC   PLANT   DISEASES  525 

fissures.  The  club-shaped  asci  bear  eight  acicular  ascospores  between 
which  are  found  paraphyses  with  hooked  tips.  These  ascospores 
measure  65  to  8o^t  by  1.5  to  3/i  and  are  ejected  forcibly  from  the  ascus. 
As  the  disease  is  not  a  serious  one,  usually  no  remedial  measures  are 
necessary.  If  the  owner  of  maple  shade  trees  wishes  to  keep  it  in 
check,  he  should  burn  the  dry  maple  leaves  which  litter  the  ground 
about  his  place. 

Melons,   Squashes,   Watermelons   {Cnciirbita  spp.) 

Anthracnose  (Colletotrichum  lagenarhim  (Pass.),  Ell.  &  Hals. — As 
an  illustration  of  a  disease-producing  fungus  included  among  the  Fungi 
Imperfecti,  we  may  describe  briefly  the  anthracnose  of  cucumbers, 
squashes,  watermelons,  Colletotrichum  lagenarium,  which  attacks 
both  leaves  and  fruits.  The  leaves  are  found  with  brown  spots  which 
cause  their  early  maturity.  If  the  fungus  attacks  the  fruits,  it  produces 
sunken  water-soaked  spots  in  which  the  acervuH  appear.  The  acervuH 
produce  numerous  conidiospores  sticking  together  to  form  viscid 
masses  of  a  pink  color.  During  moist  weather,  the  hyphae  may  grow 
out,  superficially  covering  the  fruit  with  a  mold-Uke  growth.  The 
fungus  eventually  causes  a  complete  decay  of  the  fruit.  The  disease 
has  been  prevalent  in  Nebraska  and  New  Jersey.  If  the  disease 
appears  in  greenhouse  culture,  it  is  well  to  sulphur  the  greenhouses 
thoroughly  when  they  are  empty,  and  to  clean  and  whitewash  all  the 
walls  and  woodwork  to  destroy  any  funguses  present.  Spraying  with 
Bordeaux  mixture  (3-6-50)  should  begin  when  the  vines  begin  to  trail 
over  the  ground.  Subsequent  sprayings  should  be  made  every  ten 
days,  if  the  weather  is  dry. 

Wilt  (Bacillus  tracheiphilus,  E.  F.  Sm.). — This  serious  disease  of 
cucurbitaceous  plants  was  first  reported  by  Erwin  Smith  about  1893. 
It  was  first  known  in  the  northeastern  states,  but  it  is  now  common  in 
the  middle  west  and  Rocky  Mountain  regions.  Although  pumpkins 
and  squashes  may  be  attacked  by  wilt,  yet  cucumbers  and  melons  are 
most  susceptible.  This  microorganism,  which  is  a  rod-shaped  bacillus 
two  or  three  times  as  long  as  broad,  is  actively  motile  by  wavy  cilia 
only  when  young.  It  measures  1.2  to2.5;u  by  0.5  to  0.7/i.  It  causes  a 
progressive  wilting  of  the  host  which  it  attacks.  Whether  the  whole 
plant  dies  depends  upon  the  point  of  infection,  which  is  usually  ac- 


526  SPECIAL   PLANT   PATHOLOGY 

complished  by^biting  insects.  If  a  leaf  is  attacked,  it  dies  back  to  the 
stem.  If  the  basal  part  of  the  stem  is  infected,  the  plant  rapidly 
succumbs.  This  rapid  wilting  is  due  to  the  fact  that  the  organism 
lives  in  masses  in  the  vessels  of  the  xylem  by  which  the  water  taken 
up  by  the  roots  is  distributed  throughout  the  plant,  hence  any  occlusion 
of  these  spiral  and  pitted  vessels  stops  the  water  supply  and  the  plant 
suffers.  Advanced  stages  of  the  disease  may  be  characterized  by  the 
disintegration  of  the  vascular  system  and  the  formation  of  cavities  in 
the  adjacent  parenchymatous  tissue.  Smith  sums  up  the  cultural 
characteristics  of  this  organism,  as  follows:  Stains  readily;  smooth; 
white;  viscid;  glistening;  slow  grower  on  media;  surface  colonies  small, 
round, discrete;  nogrowthat  37°C.orat  6°C.  (i6days);  aerobic;  faculta- 
tive anaerobic  (with  grape-sugar,  cane-sugar  or  fruit-sugar);  usually 
it  grays  potato  after  a  time;  clouds  peptone-bouillon  and  Dunham's 
solution  thinly;  growth  retarded  in  acid  juice  of  cucumber-fruits; 
also  retarded  or  inhibited  by  juice  of  many  vegetables,  e.g.  table-beet, 
sugar-beet,  turnip,  etc.;  grows  on  many  media  at  25°C.,  carrot,  coco- 
nut, etc.;  thermal  death  point  43 °C.;  optimum  for  growth  25°  to  3o°C., 
maximum,  34°  to  35°C.;  easily  killed  by  dry-air,  sunlight,  freezing; 
ammonia  production  moderate,  in  litmus  milk  persistent  growth  without 
reduction  or  distinct  change  in  color  of  litmus;  killed  readily  by  acids. 
Group  No.  222,  232,  2023.  As  the  disease  is  distributed  by  insects, 
the  grower  of  cucurbits  should  endeavor  to  reduce  the  number  of 
these  pests  by  the  use  of  kerosene,  or  arsenate  spray,  and  trap  plants 
should  be  grown  to  attract  the  insects  away  from  the  more  valuable 
plants. 

Oak  {Quercus  spp.) 

Decay  {Polyporus  sulphureus  (Bull.)  Fr.  Figs.  189  and  190).- — The 
decay  induced  by  Polyporus  sulphureus  is  often  called  the  red  heart-rot. 
It  attacks  not  only  oaks,  but  also  the  chestnut,  maples,  black  walnut, 
butternut,  alder,  locust,  etc.  It  is  widely  distributed  in  North  America 
and  Europe.  The  sporophores  of  this  fungus  form  a  series  of  superim- 
posed, fleshy  brackets  of  a  sulphur-yellow  color,  weighing  in  the  aggre- 
gate at  times  almost  one  hundred  pounds  (Fig.  189).  The  color  some- 
times may  vary  to  an  orange-red.  The  under  surface  is  usually  a  light 
yellow  color  and  beset  with  numerous  minute  pores.  At  maturity,  the 
fruit  bodies  lose  their  soft  character  and  become  harder  and  more  brittle. 


DETAILED    ACCOUNT   OF    SPECIFIC   PLANT   DISEASES  527 

and  frequently,  become  the  prey  of  maggots  which  riddle  them  with 
holes  and  burrows.  It  is  also  eagerly  gathered  by  mycophagists  who 
know  it  to  be  an  excellent  article  of  food. 

The  mycelium  of  the  fungus  may  live  in  the  dead  wood  of  a  tree 
after  it  has  been  killed  for  a  number  of  years,  so  that  the  same  tree  may 
produce  successive  crops  of  edible  fruit  bodies.  The  destruction,  which 
the  mycelium  works,  is  characteristic.  The  heartwood  is  reduced  to  a 
crumbly  brown  mass  which  resembles  charcoal  in  its  fracture,  but  is 


Fig.    189. — Fruiting  body  of  Polyporus  siilphureus.      {After  von  Schrenk,  Hermann, 
Bull.  149,  U.  S.  Bureau  of  Plant  Industry,  pi.  iv,  1909.) 


red-brown  in  color.  The  decayed  wood  shows  concentric  and  radial 
cracks  extending  irregularly  through  it  (Fig.  190).  As  the  wood  is  at- 
tacked and  destroyed  by  the  spreading  mycelium,  these  cracks  increase 
and  in  them  are  found  leathery  compact  sheets  of  mycelium,  which  can 
be  isolated  by  reducing  the  decayed  wood  to  a  fine  powder  by  the  blows 
of  a  hammer.  The  wood  decays  uniformly  and  is  converted  into  a 
brittle  brown  substance,  which  can  be  rubbed  to  a  fine  powder  between 
the  fingers.  Von  Schrenk  found  that  the  youngest  trees  in  which  the 
red  heart-rot  occurred  were  about  50  years  old.     The  removal  of  dis- 


528 


SPECIAL    PLANT    PATHOLOGY 


eased  trees  seems  to  be  the  only  efficient  method  of  checking  the  spread 
of  Polyporus  siilphiireus. 

Honeycomb  Heart-rot  (Stercum  subpileatnm,  W.  H.  Long). — The 
pocketed,  or  honeycomb,  heart  rot  has  been  found  on  the  following. 


Fig.  190. — Cross-section  of  a  living  post  oak  tree  rotted  by  Polyporus  sul- 
phureus.  {After  von  Schrenk,  Hermann,  Bull.  149,  U .  S.  Bureau  of  Plant  Industry, 
pi.  iv,  1909.) 


nine  species  of  02i\i's,:Querciis  alba,  Q.  lyraia,  Q.  marilandica,  Q.  MichauxU, 
Q.  minor,  Q.  palustris,  Q.  texana,  Q.  velutina  and  Q.  virginiana} 

The  first  indication  of  this  honeycomb  heart-rot  in  white  oak  is  a 
slight  discoloration  of  the  heartwood,  which  assumes  a  water-soaked 
appearance,  which  may  extend  from  i  to  6  feet  beyond  the  actual  decay. 

1  Long,  W.  H.:  A  Honeycomb  Heart-rot  of  Oaks  caused  by  Skrcuin  subpileatnm, 
Journal  of  Agricultural  Research  V:  421-428,  Dec.  6,  1915. 


DETAILED   ACCOUNT    OF    SPFCIPIC   PLANT   DISEASES  529 

The  water-soaked  heartwoocl  becomes  tawny  in  color  when  dry. 
Light-colored,  isolated  areas  now  appear  in  the  discolored  wood  and 
these  areas  originate  the  pockets.  The  rot  spreads  in  all  directions  into 
the  surrounding  tissue,  but  more  rapidly  in  the  summer  wood  of  the 
annual  ring  of  the  preceding  year,  so  that  the  bulk  of  the  pocket  lies 
in  the  summer  wood  of  one  year  and  the  spring  wood  of  the  succeeding 
year.  Delignification  now  follows  in  which  delignified  wood  fibers 
appear  in  patches  in  the  light-colored  areas,  and  this  delignification 
spreads  rapidly  until  white,  oval  to  circular  pockets  are  formed. 
These  lens-shaped  pockets  are  at  first  filled  with  white  cellulose,  which 
is  later  absorbed,  leaving  cavities.  The  diseased  area  increases  in  size 
until  the  pockets  reach  a  large  medullary  ray,  which  seems  to  check  the 
activity  of  the  enzyme,  so  that  the  larger  medullary  rays  become  the 
radial  walls  of  the  pockets.  All  the  cellulose  finally  disappears,  leaving 
the  pockets  either  (i)  empty,  (2)  containing  the  shrunken  white 
membranes  of  the  included  vessels,  or  (3)  more  or  less  filled  with  myce- 
lium. The  last  stage  of  the  rot  is  characterized  by  the  very  light  and 
honeycombed  nature  of  the  wood.  The  pockets  are  longer  than 
they  are  broad,  and  all  of  the  wood  has  disappeared,  except  the  thin 
walls  around  the  pockets,  which  remain  distinct  and  usually  involve  the 
heartwood  uniformly.  The  rotted  wood  is,  therefore,  in  the  shape  of  a 
cylinder  and  there  is  a  brownish  discoloration  of  the  heartwood  on  the 
outer  edges  of  the  affected  area. 

The  growth  of  the  mycelium  seems  to  be  preceded  by  the  enzymes 
which  cause  the  disintegration  of  the  wood.  A  few  of  the  larger  vessels 
show  hyphal  threads  and  these  become  more 'numerous,  as  delignifi- 
cation advances,  until  they  become  stuffed  with  small,  intricately 
branched,  colorless  hyphas.  When  the  hyphae  are  exposed  to  the  air, 
they  become  brown  ia  color.  The  sporophores  are  found  on  dead 
trees,  or  the  dead  areas  of  living  trees.  The  sporophores  are  thin 
shelving  bodies  formed  in. the  cracks  of  the  bark,  sometimes  assuming 
a  conchate  shape.  They  sometimes  form  in  parallel  lines,  and  range  up 
to  5  cm.  in  width.  These  sporophores  may  be  formed  on  the  dead  tree 
for  a  number  of  years.  This  fungus  is  widely  distributed  in  the  southern 
states  and  ranges  as  far  north  as  Ohio.  The  only  method  of  control 
is  to  prevent  the  infection  of  trees  by  eliminating  forest  fires,  by  pre- 
venting the  formation  of  the  sporophores,  and  the  destruction  of  all 
diseased  timber  which  has  the  rot. 


530  SPECIAL  PLANT   PATHOLOGY 

Root-rot  (Armillaria  mellea,  Vahl).' — The  "hallimasch"  of  the 
Germans,  or  the  so-called  honey  mushroom,  is  a  fungus  of  considerable 
interest  to  the  forester  (Fig.  15).  The  spores,  ifblown  to  an  exposed 
branch  stub,  may  germinate  and  produce  a  mycelium  which  works  up  and 
down  the  tree.  Infection  may  be  also  by  the  mycelium  growing  across 
from  the  roots  of  a  diseased  tree  to  a  healthy  one  through  the  soil  of 
the  forest.  In  either  case,  the  young  mycelium  grows  into  the  cambial 
layer,  attacks  the  living  cells,  and  finally  completely  encircles  the  trunk 
of  an  infected  tree.  Later  the  hyphae  are  converted  into  strands,  which 
show  a  characteristic  apical  growth,  thus  providing  for  the  elongation 
of  the  strands  through  the  host.  The  strands  of  hyphae  turn  a  deep 
chocolate-brown  color  and  are  known  as  rhizomorphs  (Fig.  15),  which 
may  anastomose  under  the  bark  of  the  tree.  Ultimately,  as  the  tree 
dies,  the  bark  splits  off  and  the  rhizomorphs  are  found  flattened  against 
the  woody  cylinder  of  the  tree.  If  such  trees  are  used  as  mine  props, 
the  strands  may  keep  on  growing  under  the  moist  even  temperature  of 
the  mine  and  there  they  may  hang  down  in  long  streamers  into  the  mine 
galleries,  as  specimens  of  such  in  the  botanic  museum  of  the  Univer- 
sity of  Pennsylvania  indicate.  The  effect  of  the  mycelium  in  the  tree 
is  to  kill  its  top  with  the  ultimate  death  of  the  entire  tree.  The 
rhizomorphs  formerly  known  as  Rhizomor pha  subterranea  grow  out 
into  the  root  system  of  the  tree,  which  they  kill,  and  here  they  may 
live  for  a  number  of  years,  endangering  the  nearby  healthy  trees, 
because  they  extend  out  into  the  soil  toward  other  tree  roots.  It  is 
this  subterranean  growth,  which  makes  the  honey  mushroom  an  ex- 
tremely dangerous  oife  to  the  hardwood  forests,  where  it  is  found. 
The  fruiting  bodies  of  this  fungus  usually  occur  grouped  in  considerable 
numbers  about  the  base  of  the  affected  tree  arising  from  the  dark-brown 
rhizomorphs,  which  thus  serve  to  connect  together  isolated  groups  of 
the  sporophores.  The  sporophores  produced  most  commonly  from 
September  to  November  are  honey-colored,  i.e.,  yellow  to  orange- 
brown,  and  their  umbonate  tops  have  a  more  or  less  viscid  character 
with  small  black  spicules  scattered  over  the  surface.  The  stipes  are 
slightly  swollen  at  the  base  and  a  short  distance  below  the  pileus  is 
found  the  ring,  or  annulus.  The  lamellae  are  dirty-white  and  from 
each  pyriform  basidium  four  white  basidiospores  fall  until  surround- 

'LoNG,  W.  H.:  The  Death  of  Chestnuts  and  Oaks  due  to  Armillaria  mellea. 
Bull.  U.  S.  Dept.  Agric.  No.  89,  1914. 


DETAILED    ACCOUNT   OF   SPECIFIC   PLANT   DISEASES  53 1 

ing  leaves  and  mosses  may  be  coated  with  a  mealy  powder  derived  from 
the  gills  of  several  sporophores  directly  over  them. 

Oat  (A vena  saliva,  Linn.) 

Rust  {Puccinia  coronifera,  Kleb)  .■ — The  oat  rust,  or  crown  rust,  affects 
oats  and  also  several  other  grasses.  The  summer  stage  appears  on 
oats  just  prior  to  the  period  of  ripening  where  it  forms  an  elongated 
uredinium  of  an  orange  color  on  the  leaves  and  sheaths.  The  globular 
spores  germinate  readily.  The  teliospores  are  formed  later  as  black 
spots  around  the  edge  of  the  uredosori.  As  the  teliospores  bear  at 
their  apex  a  crown  of  blunt  projections,  or  processes,  the  common  name 
of  "crown  rust"  has  been  applied.  Such  winter  spores  remain  in  a 
resting  condition  until  the  following  spring,  when  they  germinate  in  the 
usual  way.  The  basidiospores,  which  are  formed  from  the  basid- 
ium,  or  promycelium,  begin  growth  on  the  leaves  of  the  buckthorn, 
Rhamnus  cathartica,  where  within  eight  to  ten  days  cluster  cups 
(yEcidium  catharticce)  appear.  The  aeciospores  germinate  readily  and 
are  blown  to  the  oat  and  other  grasses,  such  as  perennial  rye  grass, 
Yorkshire  fog,  so  that  at  least  eight  forms  of  the  species  limited  to 
certain  hosts  have  been  distinguished.  The  measurements  of  its  spores 
are  as  follows:  ^ciospores,  orange,  vermiculose,  16  to  25/x  by  12  to  20^1; 
Uredospores  globose  to  obovate,  echinulate  yellow,  18  to  2  7yuby  16  to 
24/i;  teliospores  brown,  two-celled,  crowned  with  rough  projections; 
approximately  35  to  60^1  by  12  to  22)u. 

Smut  (Ustilago  avencB  and  U.  levis).  The  a-ppearance  of  this  dis- 
ease is  illustrated  in  the  figures  (Fig.  191). 

Onion   {Allium  cepa,  L.) 

Smut  (UrocysHs  ceptdcB,  Frost). — This  fungus,  probably  of  Ameri- 
can origin,  is  found  in  the  onion  growing  districts  of  the  eastern  United 
States  where  it  has  been  known  for  about  50  years.  The  smut  fre- 
quently appears  soon  after  the  first  leaf  appears,  and  is  first  in  the  form 
of  dark  spots  at  the  base  of  the  first  leaf  and  on  succeeding  leaves,  as 
they  make  their  appearance.  These  spots  are  followed  by  longitudinal 
cracks,  which  show,  a  granular  spore  powder  associated  with  threads 
of  fibrous  tissue.  The  spore  powder  under  the  microscope  is  found  to 
consist  of  the  spore  balls,  which  number  several  compacted  cells,  the 


532 


SPECIAL   PLANT   PATHOLOGY 


central  one  of  which  contains  cytoplasm,  being  surrounded  by  an 
envelope  of  sterile  cells.     Such  spore  balls  are  17  to  25)11  in  diameter 


Fig.    191. — Smut  of    oats.     A,   UsLilago  avence;  B,    Usltlago  levis       {After  Jackson, 
H.  S.,  Bull.  83,  Del.  Coll.  Agric.  Exper.  Slat.,  December,  1908.) 

and  may  retain  their  capacity  for  germination  in  the  soil  for  a  period  of 
12  years. 


DETAILED    ACCOUNT   OF    SPECIFIC   PLANT   DISEASES  533 

As  the  spores  occur  in  the  soil,  it  is  useless  to  treat  the  onion  seeds 
with  chemic  bodies.  The  most  successful  method  of  prevention  is  to 
transplant  the  seedlings  into  beds  known  to  be  free  from  smut.  Some 
growers  place  sulphur  (100  pounds  to  the  acre)  and  air-slacked  lime 
(50  pounds)  in  the  drills  as  the  seeds  are  planted. 

Orange  (Citrus  aurantium,  L.) 

Black-rot  {Alter naria  citri). — Only  navel  oranges  are  subject  to 
black  rot  which  is  recognized  by  the  premature  ripening,  large  size  of 
the  fruit  and  its  deep  red  color.  The  fungus  gains  entrance  through 
the  navel  end,  because  there  imperfections  of  the  skin  occur.  There 
soon  arises  a  black  area  of  decay  under  the  peel  which  remains  isolated 
for  some  time  without  spreading,  therefore,  the  disease  is  not  very 
virulent.  In  Alter  naria,  the  conidiophores  are  in  bundles,  always 
unbranched  and  short.  The  conidiospores  are  club-shaped  to  flask- 
shaped,  divided  and  united  into  chains  by  thinner  cells. 

Fruit-rot  {Penicillium  italicum,  Wehm.). — A  large  part  of  the  decay 
of  the  orange  and  other  fruits  of  the  genus  Citrus  is  due  to  blue  and 
green  molds.  These  molds  usually  cannot  enter  uninjured  fruits,  and 
so  their  attacks  usually  follow  a  bruise  occasioned  by  careless  handling, 
or  when  the  fruit  falls  from  the  orange  tree.  Penicillium  italicum  seems 
to  be  more  common  than  the  other  species,  P.  digitatum.  Pure  cultures 
of  this  fungus  can  always  be  secured  from  decaying  oranges  in  the 
market,  which  have  the  blue-green  areas  of  rot  just  beginning  to  appear 
upon  them.  These  areas  are  usually  blue-green  in  the  center  sur- 
rounded by  white  areas  which  are  grouped  usually  into  little  white 
patches  toward  the  vegetative  margin  and  the  whole  superficial  colony 
surrounded  by  an  area  of  soft  watery  rot.  Sometimes,  as  the  colonies 
become  older,  P.  digitatum  mixes  with  P.  italicum. 

The  conidiophores  are  short  (looju),  or  very  long  (6oo;u)  and  black 
in  media  containing  sugar.  They  average  about  250^  in  length.  The 
conidial  fructifications  are  up  to  300/1  or  more  in  length,  consisting  usu- 
ally of  a  main  branch  and  one  lateral  branch,  each  producing  a  whorl 
of  branchlets  bearing  crowded  verticils  of  conidiospores,  12  to  14^1 
by  3/i.  The  chains  of  conidiospores  are  cylindric  to  elliptic,  slightly 
ovate,  clear  green  by  transmitted  light  and  measure  2  to  3/x  by  3  to  5)u. 
Decay  of  this  sort  can  be  prevented  by  careful  handling  of  the  fruit  in 
field  and  packing  house. 


534  SPECIAL   PLANT   PATHOLOGY 

Pea  {Pisum  sativum,  L.) 

Pod-spot  {Ascochyta  pisi, 'Lih.). — The  horticulturist,  who  attempts 
to  grow  the  garden  pea,  will  find  that  the  leaves  and  pods  become 
spotted  with  conspicuous,  circular,  sunken  spots  3  to  6  mm.  in  diameter, 
which  are  dark  bordered,  pale  in  the  centers  and  slightly  pinkish  when 
mature.  Pycnidia  are  associated  with  these  spots  and  out  of  their 
porous  opening  under  favorable  conditions  the  spore  masses  may  be 
seen  issuing.  When  the  leaves  are  affected,  it  is  usually  the  lower 
leaves  which  become  diseased  first,  and  such  soon  die.  If  the  stems 
are  attacked,  the  spots  sometimes  penetrate  through  the  woody  part. 
Different  races  of  peas  differ  as  to  their  susceptibility.  The  variety 
Alaska  is  slightly  affected,  while  the  varieties  American  Wonder, 
French  June  and  Market  Garden  are  frequently  badly  diseased. 
According  to  Stevens,  the  pycnidia  consist  of  angular  cells,  5  to  7/1  with 
a  rounded  ostiole  and  reddish-brown  surface.  The  conidiospores  are 
constricted  slightly  at  the  septum,  are  oblong  and  measure  12  to  i6m  by 
4  to  6ju.  The  mycelium  perennates  in  affected  seeds,  reduces  their 
power  of  germination  and  carries  the  fungus  over  to  the  next  crop. 
Selby  has  indicated  that  healthy  peas  may  be  grown  by  spraying  with 
Bordeaux  mixture,  and  it  has  been  suggested,  that  a  two  years'  rotation 
of  non-susceptible  crops  lessens  the  prevalence  of  the  disease,  if  another 
pea  crop  is  raised. 

Peach  {Amygdalus  persica,  L.) 

Leaf  Curl  (Exoascus  deformans  (Berk.),  Fckl.)  (Fig.  192). — This 
disease  is  called  by  the  French  Cloque  du  pecker,  by  the  Germans 
Krauselkrankheit  and  by  Americans  and  English  peach  leaf  curl.  It 
is  widely  distributed  through  America,  Europe,  China  and  Japan  and 
in  Africa  and  Australia,  so  that  it  is  practically  cosmopolitan. 

The  disease  is  most  prevalent  and  most  disastrous  to  the  leaves  and 
tender  shoots  of  the  peach,  when  the  spring  months  are  damp  and  cool, 
for  records  show  that  such  conditions  prevailed  during  April  of  the 
year  1893,  1897  and  1899,  when  peach  leaf  curl  was  especially  abundant 
in  Ohio  and  New  York.  Warm  and  relatively  dry  springs  seem  to  be 
unfavorable  to  its  occurrence.  The  susceptibility  of  the  host  plants 
differs  to  a  marked  extent,  some  being  susceptible,  others  less  so. 

The  presence  of  the  disease  may  be  detected  when  the  leaf  buds 
unfold,  for  the  coloring  of  the  young  leaves  is  heightened,  and  as  they 


DETAILED    ACCOUNT    OF    SPECIFIC   PLANT   DISEASES 


535 


open  out,  the  curling  and  arching  of  the  blades  become  manifest. 
The  curling  may  be  confined  to  a  small  portion  of  a  leaf,  or  it  may  be 
general  and  all  of  the  leaves  of  a  tree  may  be  affected,  as  well  as  the 
young  stem  on  which  \hey  are  found.     The  green,  or  reddish,  color  of 


Fig.  192. — Peach  leaves  deformed  by  leaf  curl  {Exoascus  deformans).      (After  Heald, 
F.  D.,  Bull.  135  (Set.  Ser.  14),  Univ.  of  Tex.,  Nov.  15,  igoQ-) 

the  leaves  is  lost  as  they  mature,  and  they  become  pale,  or  slightly 
discolored.  Diseased  shoots  may  grow  to  twice  their  normal  diameter 
and  assume  a  characteristic  paleness.  The  diseased  leaves  finally 
turn  brown  and  drop  off  the  tree,  and  if  this  defoliation  is  excessive 


536  SPECIAL   PLANT   PATHOLOGY 

the  crop  of  peaches  may  be  nil.  The  twig  affection  is  sometimes 
associated  with  gummy  exudations,  particularly  when  the  enlargement 
is  terminal.  It  is  doubtful  whether  the  mycelium  perennates  in  the 
twigs,  as  was  supposed  in  former  years.  Infection  must  generally 
occur  as  the  buds  unfold. 

The  mycehum  of  the  fungus  may  be  studied  most  advantageously 
in  the  leaf  before  the  fungus  has  appeared  on  the  surface.  At  that  time, 
the  hyphze  show  a  greater  protoplasmic  content  and  sections  reveal 
the  fact  that  the  intercellular  inycelium  is  distributed  through  the 
mesophyll  and  cortex  of  the  young  stems.  Pierce  distinguishes  vege- 
tative hyphae,  distributive  hyphae  and  fruiting  hyphae.  The  latter 
push  up  between  the  epidermal  cells  and  a  series  of  short  hyphal  cells 
are  formed,  as  ascogenous  cells,  which  form  an  almost  continuous  layer 
beneath  the  cuticle.  The  ascogenous  cells  give  rise  to  the  asci,  which 
push  through  the  cuticle.  An  ascus  is  usually  truncate  at  the  exposed 
end  and  it  gives  rise  to  four  to  eight  ascospores,  which  may  bud  within 
the  ascus. 

Leaf  curl  may  be  controlled  by  the  use  of  lime-sulphur  solution 
(1-20),  Bordeaux  mixture  (5^5-50)  and  copper  sulphate  in  water 
(2-50),  for  the  use  of  which  the  practical  man  is  referred  to  the  spray 
calendar  given  in  the  subsequent  pages  of  this  book. 

Pear  (Pynis  commurds  L.) 

Fire-bhght  (Bacillus  amylovorus  (Bun.),  De  Trev.  Toni).^ — This 
bacterial  disease  is  found  on  the  apple,  pear  and  quince,  but  more 
especially  on  the  pear,  so  that  it  has  been  termed  pear  blight.  It  was 
first  reported  from  the  northeastern  United  States,  but  now  it  is  dis- 
tributed throughout  the  country  from  the  Atlantic  to  the  Pacific 
oceans.  The  disease  first  makes  its  appearance  in  the  early  part  of  the 
season,  when  it  appears  in  the  form  of  a  twig  blight  throughout  the  time 
of  blossoming  of  apples  and  pears,  when  the  blossoms  and  tips  begin 
to  wilt  and  show  signs  of  blackening.  This  results  in  the  complete 
blackening  and  death  of  all  the  short  branches,  or  spurs,  upon  which 
flower  clusters  have  been  borne.  The  fire  blight  disease  may  continue 
to  extend  down  the  twig,  or  the  branch,  the  branch  being  entirely 
killed,  as  it  progresses.     Under  conditions  more  favorable  to  the  host 

1  Orton,  C.  R.  and  Adams,  T.  F.  :  Collar-blight  and  Related  Forms  of  Fire- 
blight.     Bull.  136.     Penna.  Agricultural  Experiment  Station  August,  1915. 


DETAILED    ACCOUNT   OF    SPECIFIC   PLANT   DISEASES  537 

the  blight  may  extend  only  a  short  distance,  which  results  in  tip  prun- 
ing. The  bark  of  the  tree  indicates  the  progress  of  the  disease,  for 
the  soft  bark  assumes  a  water-soaked  appearance  followed  by  a  blacken- 
ing and  shriveling.  When  the  organism  ceases  to  spread  rapidly  in 
the  tissues,  there  appears  a  sharp  Hne  of  separation  between  the  dead 
and  the  healthy  tissues.  The  bark  is  broken  and  through  the  bark 
cracks  appear  gummy,  or  gelatinous,  drops  which  vary  in  color  from 
white  to  brown,  or  black. 

Bacilhis  amylovorous  was  described  first  by  Burrill  in  1877,  a  dis- 
covery full  of  significance  to  plant  pathology,  because  it  established 
the  first  bona  fide  case  of  a  plant  disease  due  to  bacteria.  It  has  been 
established,  that  infection  takes  place  through  the  visits  of  insects, 
especially  bees,  to  the  pear  flowers.  From  the  floral  nectary,  the 
bacillus  spreads  to  the  softer  tissues  of  bark  and  cambium,  where 
it  is  very  largely  confined,  and  where  it  winters  over,  spreading  to 
other  blossoms  the  next  spring.  Bacillus  amylovorus  is  an  oval 
microorganism  1.5^  to  2^1  long,  growing  singly,  or  several  attached 
end  to  end,  and  is  motile  in  fresh  cultures.  On  agar,  the  cloudy 
and  white  surface  colonies  appear  the  second  day,  and  attain  a  di- 
ameter of  2  to  3  mm.  by  the  fourth  or  fifth  day.  Cloudiness  appears  in 
bouillon  after  twenty-four  hours,  and  in  milk,  thickening  of  the  medium 
begins  at  the  third  or  fourth  day,  which  increases  until  the  fifth,  or 
sixth  day,  when  the  product  is  finally  partially  gelatinous  with  a  clear 
acid  liquid  above,  changing  to  slightly  alkaline. 

The  work  of  Waite  has  shown  that  pear  blight  can  be  controlled 
by  pruning  out  the  blight  during  winter,  so  as  to  eliminate  the  source 
of  infection  during  the  next  year,  and  if  this  pruning  is  done  thoroughly, 
the  disease  can  be  kept  in  check.  The  stubs  should  be  disinfected 
with  corrosive  sublimate  (i-ioo). 

Pine  (Pi litis  spp.) 

Blister-rust  (Cronartium  ribicoliim,  Fisch  &  Waldh.  =  Pcrl- 
dermium  strobi,  Klebahn).^ — This  disease,  as  it  appears  on  white  pine, 

^  Spaulding,  Perley:  The  White  Pine  Blister  Rust  Situation,  American 
Forestry  22,  pp.  137-138,  March,  1916;  The  BHster  Rust  of  White  Pine,  Bull.  206, 
U.  S.  Bureau  Plant  Industry,  191 1;  also  consult  American  Forestry.  Feb.,  Mch.,  Dec, 
1916.  In  the  December,  1916,  number  a  map  showing  the  distribution  of  the 
disease  is  given.  A  conference  was  held  at  Washington  in  January,  1917,  to 
consider  the  establishment  of  stricter  quarantine  regulations  of  the  methods  of 
checking  the  spread  into  the  western  states. 


538 


SPECIAL   PLANT   PATHOLOGY 


has  been  considered  to  be  of  such  great  importance,  that  strict  quaran- 
tine regulations  were  established  in  order  to  keep  it  out  of  the  country, 
but  the  result  of  a  thorough  exploration  of  the  New  England  States 
during  the  summer  of  1916  has  shown  its  general  distribution  through- 
out them  and  even  as  far  west  as  Minnesota.     It  appears  to  have  been 


Fig.  193. — White  pine  blister-rust,  Cronarliutn  ribicola.  A,  Diseased  tree  with 
aecial  blisters  broken  open  from  which  spores  are  blown  to  currant  or  gooseberry- 
leaves;  B,  D,  teliosori  on  under  leaf  surface  of  currant,  Ribes.  {From  Gager,  after 
Perley  Spaidding.) 

introduced  into  America  on  nursery  stock  from  Holland,  and  all  the 
trees  in  these  advanced  posts  of  infection  have  been  destroyed.  In 
igo6,  there  was  an  outbreak  on  currants  at  Geneva  and  measures  were 
taken  to  destroy  the  fungus  in  that  vicinity.  The  aicidial  stage,  known 
as  Peridermium  sirobi,  appears  on  the  pine  tree  and  the  uredinia  and  the 


DETAILED   ACCOUNT   OF   SPECIFIC   PLANT   DISEASES  539 

telia  on  species  of  the  genus.  Ribes,  viz.,  R.  aureum,  R.  nigrum,  R. 
rubrum  with  which  intermediate  hosts  (it  does  little  damage.  The 
susceptibiHty  of  different  currants  varies  considerably  (Fig.  193). 

The  attacked  white  pine  trees  are  stunted,  the  tops  show  a  bushy 
growth  and  the  part  of  the  tree  where  the  mycelium  occurs  is  swollen. 
The  leaves  of  the  currant  infested  by  the  fungus  are  thicker  in  texture 
and  assume  a  different  color.  The  aecidia  are  erumpent  from  the  bark 
in  the  form  of  a  bladder  with  an  inflated  peridium  about  one  centi- 
meter high  and  yellowish-white.  The  spores  are  roundish,  or  poly- 
gonal, coarsely  verrucose,  orange  in  color  and  measure  22  to  29/i  by  18  to 
20/i.  The  urediniospores  form  orbicular  groups  surrounded  by  a  deUcate 
peridium  which  opens  at  the  summit  with  a  pore.  They  are  ellipsoid 
to  obovoid  in  shape,  echinulate,  orange  and  their  dimensions  are 
21  to  24/i  by  14  to  i8/i.  The  smooth  teliospores  are  crowded  along  the 
veins  of  the  leaf.  They  are  orange  to  brownish-yellow,  70/i  long  by 
2i/i  broad. 

This  serious  disease  may  be  controlled  by  the  destruction  of  the 
hosts,  namely,  the  currant  and  gooseberry  bushes  especially  in  the  wild 
state.  This  disease  threatens  the  extinction  of  all  the  species  of  five- 
leaved  pines  including  those  of  the  Pacific  States,  such  as  sugar  pine, 
Pinus  lambertiana. 

Red-rot  {Poly poms  ponder osus,  H.  von  Schrenk). — The  red  rot  of 
the  western  yellow  pine  {Pinus  ponderosa)  usually  starts  in  the  tops  of 
the  "black-top"  trees,  i.e.,  trees  which  have  been  dead  for  two  or  more 
years.  At  one  or  more  points,  one  will  find  that  the  wood  immediatelv 
under  the  bark  starts  to  rot  and  the  rot  proceeds  inwardly  to  the  wood 
which  becomes  wet  and  soggy,  and  rapidly  becomes  brittle,  so  that  it 
crumbles  into  small  pieces  when  rubbed.  The  color  of  the  wood  changes 
to  blue  and  later  to  red  yellow.  When  the  decay  has  gone  on  for 
some  time,  bands  and  sheets  of  a  white  felty  substance  consisting  of 
masses  of  hyphae  are  found  filling  certain  cracks  which  result,  because 
of  shrinkage  in  the  wood  mass.  The  destruction  of  the  wood  continues 
until  the  heartwood  is  reached. 

Red-rot  is  caused  by  a  higher  fungus  which  enters  the  tree  through 
beetle  holes  made  into  the  dead  cambium  of  the  wood  killed  by  the 
"blue"  fungus  which  precedes  the  red  rot.  When  the  wood  has  been 
completely  destroyed  red-rot  fungus  forms  its  sporophores  which  begin 
to  grow  out  from  the  mycelium,  as  flesh-colored  knobs,  which  rapidly  in- 


540 


SPECIAL   PLANT   PATHOLOGY 


crease  in  size  and  turn  reddish  in  color,  assuming  the  form  of  a  bracket, 
or  shelf.  The  lower  surface  is  beset  with  pores,  or  tubes,  on  the 
walls  of  which  the  spores  are  borne.     This  bracket  fruit  may  grow 

many  years,  and  it  adds  a  ring  on  the 
outside  when  new  growth  com- 
mences. The  fruit  bodies  may  occur 
singly  or  in  groups  of  two  or  three 
together.  They  are  rough  on  top 
and  appear  to  be  covered  with  a  waxy 
substance,  which  has  hardened  and 
cracked.  It  is  brittle  and  readily 
soluble  in  alcohol  and  xylol.  The 
lower  surface  is  smooth  with  regular 
pores.  ^ 

Plum  {Primus  americana,  Marsh) 

Black-knot  (Plowrightia  morbosa 
(Schw.),  Sacc). — The  black  knot 
was  at  first  mainly  confined  to  the 
New  England  states,  but  it  now  ex- 
tends across  the  northern  United 
States  to  the  Pacific  coast  with 
areas  free  from  the  disease  in  the 
middle  west  and  southwest.  Several 
species  of  plums  and  cherries  are  sus- 
ceptible. 

The  disease  appears  as  wart-like 

excrescences    on    the     smaller    and 

larger  branches  of  plum  trees  (Fig. 

„,    ,  ,  ,     ,  104)  which  it  either  surrounds  com- 

FiG.    194. — Black-knot    of    plum,        ^       ....  .       , 

Plowrightia  morbosa,  on  cultivated  pletcly  killmg  the  termmal  part  of 
plum,  Cold  Spring  Harbor,  L.  L,  July    the  branch,  or  Only  part  way  round 

when    the    branch   continues   living 
and  fruit-bearing  (Fig.  194).     The  common  name  is  well  given,  because 

Won  Schrenk,  Hermann:  The  "Bluing"  and  the  Red  Rot  of  the  Western 
Yellow  Pine,  with  Special  Reference  to  the  Black  Hills  Forest  Reserve.  U.  S.  Bureau 
of  Plant  Industry  Bull.  36,  1903. 


DETAILED   ACCOUNT   OF   SPECIFIC   PLANT   DISEASES  541 

the  hypertrophies  are  black  in  color.  The  knot  begins  as  a  slight 
swelling  of  the  branch,  and  as  the  swelling  increases  in  size  the  bark 
is  cracked  (Fig.  194). 

The  mycelium  of  the  fungus  occupies  the  cambium  and  bast  areas 
of  the  stem,  extending  throughout  the  cortex  also.  The  knot  consists 
of  dense  areas  of  the  fungus  and  tissue  elements  of  the  host.  Bast 
fibers,  parenchyma  cells  and  even  vessels  may  be  found  in  the  gall 
tissue.  In  the  spring,  small  greenish  areas  may  be  noticed  on  the 
surface  of  the  knot,  and  later,  the  hyphae  break  through  the  bark  in 
all  directions  and  form  a  pseudoparenchymatous  layer.  This  stomatic 
layer  gives  rise  to  the  conidiospores,  which  are  fiexuous  and  septate. 
The  conidiophores  are  40  to  6o/i  by  4  to  5)U  and  the  conidiospores 
abstricted  off  are  light  brown  in  color.  Conidiospores  are  formed 
from  Spring  to  late  midsummer.  They  are  simple  and  light  brown 
in  color.  The  fungous  stromata  is  covered  with  papillae  which  locate 
the  opening  of  the  perithecia  which  include  the  asci  with  eight  asco- 
spores,  that  ripen  during  midwinter,  or  later.  Each  ascus  is  120/i  in 
length  and  the  ascospores  measure  16  to  20 fx  by  8  to  lo/j..  Between 
the  asci  are  paraphyses. 

Since  the  conidial  stage  is  produced  during  late  Spring  and  early 
Summer  pruning  out  the  developing  knots  is  found  an  efficient  remedy 
in  most  cases  against  black  knot. 

Plum  Pockets  {Exoascus  Pruni,  Fckl.).^ — The  plum  pocket  fungus  is 
widely  distributed  over  the  United  States  and  Europe  and  its  etiology 
of  the  disease  it  produces  is  somewhat  similar  to  that  of  the  peach  leaf 
curl.  The  mycelium  lives  in  the  flower  buds  and  causes  remarkable 
changes  in  the  ovaries,  as  they  develop  into  fruits.  The  hyphae  are 
found  in  the  mesocarp,  the  cells  of  which  are  stimulated  to  form  a 
spongy  growth,  so  that  the  plum  fruit  becomes  swollen  and  somewhat 
distorted.  As  a  result  of  the  fungus  attack,  the  endocarp  which  nor- 
mally would  develop  a  putamen,  or  stone,  fails  to  do  so,  and  no  stone, 
or  seed,  is  formed,  but  in  their  place  a  cavity  appears  which  gives  the 
common  name  to  the  disease.  The  mycelium  is  probably  perennial  in 
the  twigs  of  the  plum  tree  and  is,  therefore,  in  a  position  to  grow  out 
into  the  young  ovaries  of  the  next  succeeding  crop  of  flowers.  The 
ascogenous  cells  develop  beneath  the  cuticle  of  the  well-formed  fruits 
and  finally  rupture  the  latter,  appearing  as  a  velvety  layer.  The  asci 
are  30  to  6o/i  by  7  to  12^1,  although  Robinson  notes  a  certain  dimor- 


542  SPECIAL  PLANT   PATHOLOGY 

phism  of  the  asci  where  these  figures  vary.     Each  ascus  contains  eight 
ascospores  which  measure  4  to  5/i  (Fig.  42). 

Potato  {Solaniim  tuberosum,!^.) 

Late-bHght  {Phytophthora  infestans,  deBy). — Historically,  this  is 
one  of  the  most  interesting  of  fungi,  for  in  1845  the  potato  crops 
of  the  British  Isles,  especially  Ireland,  were  decimated  by  the  late 
blight  to  such  an  extent  as  to  cause  a  severe  famine  in  Ireland.  This 
famine  caused  the  emigration  of  hundreds  of  thousands  of  people  from 
the  Emerald  Isle  to  America  and  the  British  parHament  in  order  to 
alleviate  the  distress  of  the  poor  repealed  the  corn  laws,  and  thus 
began  the  free  trade  policy  of  that  country. 

Formerly,  it  was  thought  that  the  potato  disease  was  distributed 
widely  in  America,  but  it  is  now  known  to  be  most  prevalent  in  New 
England,  in  New  York  and  the  Canadian  provinces,  where  the  potato- 
growing  industry  is  an  important  one.  It  has  a  wide  range  in  Europe 
and  is  known  throughout  Great  Britain  and  from  France  to  Russia, 
being  especially  favored,  as  it  was  in  1845,  by  warm  damp  weather  in 
the  summer  months. 

The  disease  is  characterized  by  leaf  spots  which  first  appear  at  the 
margin,  or  apex  of  the  leaf,  and  spread  over  its  surface  until  the 
leaf  presents  a  dark  somewhat  water-soaked  appearance.  These  spots 
are  brown  in  drier  weather  and  in  all  cases  a  withering  of  the  leaf  fol- 
lows the  attack  of  the  mycelium.  The  disease  is  known  as  dry-rot, 
when  it  develops  in  the  tubers,  for  the  hyphae  enter  the  cells,  as  haus- 
toria  kill  the  cells,  and  the  condition  of  the  tuber  known  as  dry  rot 
is  produced,  which  may  be  found  especially  in  the  stored  tubers. 

The  hyphae  of  the  late-blight  fungus  are  unicellular  and  they  spread 
through  the  intercellular  spaces  of  the  host  sending  filamentous  haus- 
toria  into  the  cells  of  the  leaves,  or  tubers.  From  this  internal  myce- 
lium, long  branched  (dendritic)  conidiophores  grow  out  through  the 
stomata  and  the  branches  bear  either  laterally,  or  apically,  egg-shaped 
conidiospores,  which  measure  2  7  to  30/x  by  1 5  to  20/i.  The  conidiospores 
on  germination  form  eight  biciliate  zoospores,  which  are  motile  for  a 
brief  time  perhaps  not  longer  than  an  hour.  If  one  of  these  swarm 
spores  finds  its  way  to  a  leaf,  germination  speedily  follows  and  the 
hyphal  germ  tube  enters  the  interior  of  the  leaf  either  through  a 
stoma,  or  by  boring  a  hole  through  the  epidermis. 


DETAILED   ACCOUNT   OF   SPECIFIC   PLANT   DISEASES  543 

The  germ  tube  of  the  swarm  spores  penetrate  the  tuber,  as  easily 
as  the  leaf,  if  they  happen  to  be  washed  down  to  the  soil.  Recently 
G.  P.  Clinton^  has  discovered  the  oogonia,  antheridia  and  oospores  of 
Phytophthora  injestans  after  they  had  been  sought  for  by  mycologists 
since  1845,  and  thus  an  American  mycologist  has  added  one  more 
achievement  to  the  list  of  important  work  accomplished  by  American 
scientific  men. 

Spraying  the  foliage  with  Bordeaux  mixture  (5-5-50)  has  proved 
an  almost  complete  remedy  against  both  the  Phytophthora  blight  and 
the  rot,  and  also  operates  beneficially  to  the  potato  plant  in  other  ways. 
Burying  the  tubers  to  a  sufficient  depth  (about  4  to  5  inches)  has  been 
found  beneficial,  as  also  the  disinfection  of  the  tubers  designed  for  seed 
purposes  by  exposure  to  dry  heat  40°C.  (i04°F.)  for  four  hours.  Tuber 
infection  may  be  prevented  by  spraying  the  soil,  even  when  the  fungus 
is  allowed  to  develop  unchecked  on  the  foliage.  When  the  tops  are 
attacked  by  late-blight,  the  harvesting  of  the  tubers  should  be  delayed 
until  a  week  or  more  after  the  death  of  the  tops.  Longer  delay  does  no 
harm,  unless  the  season  be  wet  and  the  soil  exceptionally  heavy.  Dry 
cool  storage  is  of  primary  importance,  the  use  of  lime,  or  formalin,  for 
disinfection  being  valueless.^  It  seems  from  investigations,  that  have 
been  made,  that  well-marked  and  fixed  diflferences  exist  among  potato 
varieties  in  relative  susceptibility  to  invasion  by  the  late-blight  fungus, 
in  other  words,  in  disease  resistance. 

Powdering  Dry-rot  {Fusarium  trichothecioides  Wollenw.). — This 
fungus  kept  in  artificial  culture  has  been  used  successfully  in  the  artifi- 
cial inoculation  of  potato  tubers,  as  laboratory  exercise  with  univer- 
sity students  in  mycology.  In  every  case,  the  rot  has  been  secured  and 
the  students  have  imbedded  pieces  of  tuber  and  fungus  in  paraffin; 
cut  the  same  with  a  rotary  microtome  and  mounted  and  stained  the 
sections  for  microscopic  study. 

Fusarium  trichothecioides  forms  two  kinds  of  conidiospores:  (i)  The 
comma  type,  formed  as  a  slightly  curved  comma  ellipsoidally  rounded 
on  both  sides;  and  (2)  the  normal  macroconidiospores.     The  plecten- 

1  Clinton,  G.  P.:  Oospores  of  Potato  Blight.  Report  of  the  Connecticut 
Agricultural  Experiment  Station,  1909-1910:  753-774  with  3  plates. 

2  Jones,  L.  R.,  Giddings,  N.  J.  and  Lutman,  B.  F.:  Investigations  of  the  Potato 
Fungus,  Phytophthora  infestans.  Bull.  245  U.  S.  Bureau  of  Plant  Industry, 
1912,  with  full  bibliography;  Melhus,  I.  E.,  Hibernation  of  Phytophthora  infestans 
of  the  Irish  Potato.    Journ.  Agric.  Research  V:  71-102. 


544  SPECIAL   PLANT   PATHOLOGY 

chymatic  mycelium  and  conidial  masses  are  rosy  white.  The  powdery 
dry-rot  with  pink  mycelium-Uned  cavities  is  quite  characteristic  and 
not  easily  confused  with  the  other  species  of  Fusarmm  found  on 
potatoes.^ 

Scab  {Actinomyces  chromogenes). — This  scab  disease  is  one  well- 
known  throughout  the  United  States  and  also  in  Europe,  although 
all  the  cases  of  scabby  potatoes  are  probably  not  due  to  this  fungus, 
as  a  causal  organism.  Turnips,  beets  and  mangels  are  susceptible 
to  the  disease  while  carrots  and  parsnips  are  not.  The  first  symptoms 
of  the  disease  are  minute  reddish-brown  spots  on  the  surface  of  the 
tuber  beginning  usually  at  one  of  the  lenticels  of  the  tuber  and  spread- 
ing rapidly  to  other  tissues,  assuming  a  deeper  color  and  an  abnormal 
corky  development  over  considerable  areas.  Thus  arise  the  scab-like 
crusts  which  have  given  the  common  name  to  the  disease.  The  surface 
of  the  tuber  frequently  becomes  cracked  to  considerable  depths.  If 
scabby  potatoes  are  examined  immediately  after  being  gathered  a  fine 
grayish,  evanescent  film  will  be  found  consisting  of  extremely  delicate, 
minute,  refractive,  branched  filaments,  which  break  up  into  bacteria- 
like  cells.  Some  branches  are  curved  and  structures  suggesting  true 
spores  are  produced  in  certain  cells.  The  writer  has  found  the  fungus 
as  minute  white  specks  on  horse  manure.  It  has  been  found  to 
persist  in  the  soil  for  several  years. 

The  disease  can  be  controlled  by  soil  treatment,  by  the  adoption  of 
a  rational  rotation  of  crops  and  by  planting  seed  tubers  only  after  they 
have  been  treated  for  several  hours  with  a  solution  of  i  ounce  of 
formalin  to  every  2  gallons  of  water,  or  by  a  solution  of  corrosive 
sublimate  in  water. 

Raspberry  {Rubus  occid entails,  L.) 

Anthracnose  {Glceosporlum  vcnetum,  Speg.). — As  this  fungus  pro- 
duces injuries  to  the  raspberry  and  blackberry  canes,  it  was  called  by 
Burrill,  who  published  the  first  account  of  the  disease  in  1882,  the  "rasp- 
berry cane  rust."  It  is  known  to  occur  in  New  Jersey,  Illinois,  Texas, 
Wisconsin,  Missouri  and  other  states. 

The  fungus  attacks  both  fruiting  and  non-fruiting  canes,  or  suckers, 

1  Carpenter,  C.  W.:  Some  Potato  Tuber-rots  caused  by  Species  of  Fusarium. 
Journal  Agricultural  Research  V:  183-209,  Nov.  i    1915. 


DETAILED    ACCOUNT    OF    SPECIFIC   PLANT   DISEASES  545 

producing  small  purple  spots  that  are  variously  scattered  along  the 
cane.  The  spots  first  formed  rapidly  increase  in  size,  and  as  the 
fungus  develops  the  center  of  each  becomes  grayish-white  in  color  sur- 
rounded by  a  slightly  raised,  dark-purple  border,  separating  the 
healthy  from  the  diseased  tissues.  The  disease  progresses  in  an  up- 
ward direction  and  as  the  advanced  stage  of  the  malady  is  reached, 
the  spots  coalesce.  The  greatest  injury  is  to  the  cambium,  so  that 
the  living  tissues  of  the  cane  become  sickly,  the  leaves  do  not  attain 
half  their  normal  size,  the  fruit  ripens  prematurely,  or  dries  up  as 
worthless.  The  petioles  of  the  older  leaves  may  be  attacked  and  later 
the  veins  of  the  leaves  which  show  whitisii,  blister-like  spots.  The 
spots  on  the  lamina  are  smaller  than  on  the  canes. 

The  mycelium  lives  in  the  intercellular  spaces  of  the  host,  but  is 
supplied  from  the  neighboring  host  cells  with  nutritive  materials. 
There  is  at  first  a  slight  discoloration  of  the  cell  contents,  the  cells 
then  lose  their  shape  and  finally  collapse.  The  conidiophores  are 
formed  beneath  the  epidermis  of  the  host  and  later  appear  at  the 
surface  bearing  the  conidiospores,  which  are  surrounded  by  a  gelatinous 
substance.  Pruning  away  the  diseased  canes  and  burning  them  in  a 
brush  heap  is  the  most  important  means  of  controlUng  the  raspberry 
anthracnose.  Spraying  early  in  the  season  with  Bordeaux  mixture 
(4-4-50)  is  useful,  although  not  an  absolute  preventive. 

Red  Gum  {Liquidamhar  styraciflua,  L.) 

Sap-rot  {Polystictus  versicolor  (L.),  Fr.). — Polystictus  versicolor  is 
one  of  the  most  cosmopoHtan  species  of  fungi  known.  It  is  known  from 
Europe,  Africa,  Australia,  South  America,  Mexico,  Japan,  the  West 
Indies  and  throughout  the  United  States.  It  grows  on  the  sapwood 
of  every  species  of  deciduous  tree  known.  It  is  the  most  serious  of  all 
the  wood-rotting  fungi,  destroying  probably  75  per  cent,  of  the  timber 
used  for  railroad  ties.  A  broad  sheet  of  mycelium  covers  the  entire 
surface  of  the  timber  on  which  it  grows,  but  it  develops  in  the  wood, 
especially  the  sapwood,  in  which  decay  takes  place  with  great  rapidity.^ 
There  is  a  rapid  solution  of  the  various  parts  of  the  woody  structure 
for  the  fungus  has  no  preference  for  either  the  lignin,  or  the  cellulose 

1  Stevens,  Neil  E.:  Polystictus  Versicolor  as  a  Wound  Parasite  of   Catalpa. 
Mycologia,  vi;  263-270,  Sept.,  1912;  see  Ante  p.  75. 
35 


546  SPECIAL   PLANT   PATHOLOGY 

parts  of  the  cell  wall,  and  the  parts  of  the  springwood  fall  apart  readily, 
because  of  their  porous  character.  The  fruiting  bodies  of  this  fungus 
are  extremely  variable  depending  upon  the  kind  of  wood  on  which  they 
grow.  The  sessile  sporophores  may  grow  singly,  or,  more  usually, 
many  of  them  together,  forming  a  series  of  closely  overlapping  brackets. 
They  are  readily  recognized  by  the  soft,  hairy  upper  surface  with  bands 
of  white  and  yellow  color,  although  these  colors  are  variable.  The 
young  sporophores  are  fleshy,  but  become  leathery  with  age.  Their 
lower  surface  is  white  and  the  pores  are  minute  and  regular.  Treat- 
ment of  the  wood  with  chemic  preservatives  has  been  found  efficacious 
in  preventing  the  attack  of  such  fungi  as  Polystidus  versicolor,  and 
most  of  our  large  railroads  have  machinery  where  the  steeping  of 
the  ties  in  chemic  preservatives  can  be  accomplished  quickly  and 
inexpensively. 

Rye  (Secale  cerale,  L.) 

Ergot  (Claviceps  purpurea,  Tul.)  (Figs.  56  and  57), — The  ergot  fun- 
gus is  found  on  rye  both  in  America  and  Europe,  where  during  wet 
warm  weather  it  may  be  extremely  prevalent.  It  gains  entrance  to  the 
host  at  the  base  of  the  young  ovary  penetrating  the  ovary  wall  and 
gradually  replacing  the  tissues  of  the  rye  ovary.  This  is  accompanied 
by  an  enlargement  of  the  ovary  which  at  its  upper  end  presents  a  some- 
what spongy  character.  This  is  due  to  the  outgrowth  of  the  mycelium 
in  the  form  of  twisted  strands,  the  marginal  hyphas  of  which  acting 
as  conidiophores  abstrict  off  conidiospores.  This  early  stage  was 
known  as  the  Sphacelia  stage.  Later,  as  the  time  for  the  maturing  of 
the  healthy  grains  arrives  the  diseased  ovaries  will  be  found  to  be  re- 
placed by  bluish-black  horn-like  bodies  which  project  conspicuously 
from  between  the  glumes  of  the  rye  spikelet.  The  rye  ovary  is  re- 
placed by  a  hard  body  with  a  blackish  surface  and  white  interior 
known  as  the  sclerotium.  The  ergot  spurs,  or  sclerotia,  perennate  as 
such  until  the  following  spring,  when  they  send  up  one  or  several 
outgrowths,  or  stroma,  with  a  knob-like  end  of  a  yellowish-brown  color. 
In  the  hyphal  tissue,  which  comprises  the  knob-like  portion  of  the 
stroma,  fiask-shaped  perithecia  are  formed  with  short  necks  and 
slightly  protruding  ostioles.  The  asci  contained  in  these  perithecia 
are  elongated  and  contain  eight  needle-shaped  ascospores,  which 
measure  60  to  70/i  in  length,  and  issue  from  the  tip  of  the  ascus  by 


DETAILED   ACCOUNT    OF    SPECIFIC   PLANT   DISEASES  547 

a  small  opening.  These  ascospores  bud  off  conidiospores,  which  are 
capable  of  infecting  the  ovaries  of  rye  plants,  which  have  started  their 
growth  toward  maturity  the  following  season. 

The  ergot  spurs  are  used  medicinally  under  police  regulations,  for 
they  are  dangerous  and  poisonous.  In  the  Baltic  provinces  of  Germany 
and  Russia,  the  peasant  class  frequently  eat  bread  made  out  of  flour  in 
which  ergot  spurs  have  been  ground.  They  suffer  from  gangrenous 
affections  of  the  extremities  with  a  loss  of  the  hair,  teeth  and  finger- 
nails. A  nervous  form  of  ergotism  has  also  been  prevalent.  Cattle 
eating  ergoted  grain  show  similar  gangrenous  and  nervous  symptoms, 
the  loss  of  hoofs,  tails  and  horns. 

Ergot  can  be  controlled  to  some  extent  by  the  selection  of  the  grain 
seed  and  by  removal  of  all  ergoted  masses,  when  detected  in  the 
fields. 

A  closely  related  species,  Claviceps  microcephala  (Wallr.),  TuL,  was 
submitted  to  the  writer  by  the  late  Dr.  Leonard  Pearson  on  red-top 
hay,  which  had  been  responsible  for  gangrenous  affection  of  a  herd  of 
cattle  in  Pennsylvania. 

Sweet  Pea  (Lathyrus  odoratus,  L.) 

Streak  {Bacillus  lathyri,  Manns  &  Taubenhaus). — This  disease  had 
been  noted  by  the  growers  of  the  sweet  pea  in  England,  and  recently, 
it  has  been  detected  in  the  United  States.^  Like  the  bacteriosis  of 
beans,  streak  makes  its  appearance  in  the  season  of  heavy  dew.  On 
the  sweet  pea,  the  disease  usually  appears  just  as  the  plants  begin  to 
blossom;  it  is  manifested  by  light  reddish-brown  to  dark  brown  spots 
and  streaks  (the  older  almost  purple)  along  the  stems,  having  their 
origin  near  the  ground,  indicating  distribution  by  spattering  rain  and 
infection  through  the  stomata.  The  disease  becomes  quickly  dis- 
tributed over  the  more  mature  stems  until  the  cambium  and  deeper 
tissues  are  destroyed  in  continuous  areas,  when  the  plant  prematurely 
dies.  From  the  stems  the  disease  spreads  to  the  petiole,  peduncles, 
flowers  and  pods  with  symptoms  similar  to  those  on  the  stems.  On  the 
leaves,  however,  the  disease  appears  as  small  roundish  spots,  which 
gradually  coalesce,  and  eventually  involve  the  entire  leaf,  which  when 

^  Taxjbenhaus,  J.  J.:  The  Diseases  of  the  Sweet  Pea.  Bull.  106.  Delaware 
Agricultural  Experiment  Station,  Nov.,  1914. 


548 


SPECIAL   PLANT   PATHOLOGY 


killed  presents  a  dark-brownish  appearance.     If  the  causative  organ- 
ism, which  is  a  small  rod-shaped  bacillus,  is  sprayed  upon  the  sweet 

pea  plant,  the  disease  makes  its  ap- 
pearance from  seven  to  ten  days 
after  artificial  infection  and  the 
symptoms  are  similar  to  those  pro- 
duced in  nature.  The  bacillus  is 
rarely  found  in  chains  and  seldom 
united  in  twos  or  fours.  Its  fiagella 
are  not  easily  demonstrated,  as  they 
are  shed  so  readily  that  not  more 
than  two  to  five  may  be  stained 
and  these  are  generally  quite  short. 
If  properly  fixed  and  stained,  very 
long  delicate  flagella  may  be  dem- 
onstrated, 8  to  12  in  number,  and 
peritrichous. 

Sweet  Potato    {Ipomoea   batatas), 
Poir) 

Black-rot  {SphcEronema  fimbriata 
(Ell.  &  Hals.),  Sacc.).^We  owe  our 
past  knowledge  of  this  disease  to 
Halsted,  who  in  1890  described  this, 
as  well,  as  other  diseases  of  the  sweet 
potato.  It  is  a  seed-bed  disease,  a 
field  disease  and  a  storage  trouble. 
It  is  characterized  by  irregular  hard, 
dark  areas,  or  circular  spots,  varying 
in  size  from  that  of  a  dime  to  that  of 
a  silver  dollar  appearing  on  the  skin 
of  sweet  potatoes  (Fig.  195).  If  the 
root  is  injured,  the  fungus  follows 
the  line  of  injury.  The  sprouts  are 
dwarfed  and  the  foliage  turns  yel- 
low. The  end  of  the  hank  is  black- 
ened and  charred  and  this  is  asso- 
ciated with  a  withering  of  the  leaves  which  become  black  and  crisp. 


Fig.  195. — Sweet-potato  black 
rot  produced  by  a  fungus,  Sphar- 
onema  fimbriatum.  (After  Harler, 
L.  L.,  U.  S.  Farmers'  Bull.  714, 
March  11,  1916.) 


DETAILED    ACCOUNT   OF    SPECIFIC   PLANT   DISEASES  549 

Frequently,  the  stems  and  petioles  are  affected  and  black  areas  appear 
on  them.  In  the  field  the  appearance  of  black  girdling  lines  between 
two  leaves  is  an  indication  of  the  disease.  The  part  below  the  black 
line  remains  healthy,  while  that  above  wilts  and  dies.  Stem  infection 
is  not  always  associated  with  root  infections. 

The  black-rot  parasite  lives  skin  deep  on  the  roots  extending  only 
to  the  cambial  layer,  while  in  infected  stems,  leaves  and  rootlets,  it 
invades  all  parts.  The  hyphae  are  septate  and  the  cells  are  filled 
with  oil  globules.  They  are  capable  of  breaking  up  into  as  many  spores 
as  there  are  cells,  and  these  spores  are  denominated  chlamydospores. 
Olive-brown  conidiospores  are  also  formed  and  these  are  cut  off  from 
terminal,  or  lateral  branches.  The  pycnidia  are  formed  within  the 
diseased  areas,  and  they  can  be  had  in  artificial  cultures.  They  are 
flask-shaped  with  extremely  long  necks.  The  pycnospores  are  more  or 
less  subglobose,  or  oblong,  hyaline  and  measure  5yu  to  gn  in  length.  The 
mycelium,  which  has  developed  to  a  considerable  extent  on  the  root, 
may  develop  sclerotia  of  a  large  size  by  which  the  fungus  perennates, 
and  it  may  also  live  over  on  stored  roots  and  pieces  of  roots  left  in  the 
field.  Pure  cultures  of  the  fungus  are  not  difficult  to  obtain.  It 
grows  well  on  any  starchy  medium,  such  as  sweet  and  white  potato 
cylinders  and  on  bean  agar.  As  to  the  spread  of  the  fungus,  various 
mites,  as  well,  as  watering  the  plants,  help  to  distribute  the  pycnospores. 
Roots  attacked  by  the  black  rot  fungus  have  a  bitter  taste.' 

The  disease  can  be  controlled  by  the  careful  selection  of  seed 
roots  and  by  a  judicial  rotation  of  crops.  ■ 

Sycamore  (Platanus  occidentaUs,  L.) 

Blight  {Gnomonia  venela  (Sacc.  &  Speg.)  Kleb.). — Within  the  last  few 
years  in  southeastern  Pennsylvania,  the  sycamore,  or  plane  trees  have 
been  visited  in  the  spring,  when  the  young  leaves  are  about  half 
developed,  by  attacks  of  this  fungus,  so  that  the  young  leaves  appear 
as  if  destroyed  by  early  frosts.     It  is  sometimes  very  disastrous,  es- 

1  Wilcox,  E.  Mead:  Diseases  of  Sweet  Potatoes  in  Alabama.  Alabama  Agric. 
Exper.  Stat.  (Auburn)  Bull.  135,  June,  1906;  Taubenhaus,  J.  J.  and  Manns, 
Thos.  F.:  The  Diseases  of  Sweet  Potato  and  Their  Control.  Delaware  Agric.  Exper. 
Stat.  Bull.  109,  May,  1915;  Taubenhaus,  J.  J.:  The  Black  Rots  of  the  Sweet 
Potato.     Phytopathology  III:   159-165. 


5 so  SPECIAL   PLANT   PATHOLOGY 

pecially  in  low-lying  country,  as  along  stream  banks,  or  in  closed-in 
valleys.  Whole  trees  are  practically  attacked,  the  young  leaves  turn 
brown  and  then  they  begin  to  wither  and  finally  curl  up  into  a  brittle 
mass.  It  also  produces  spots  on  the  leaves  of  the  white,  black,  and 
scarlet  oaks. 

Until  the  life  history  of  this  fungus  was  fully  known,  it  was  con- 
sidered as  three  distinct  types  of  imperfect  fungi  by  the  older  my- 
cologists. The  fungus  known  as  Glceosporium  nervisequum  represents 
the  stage,  which  appears  upon  the  leaves  in  the  form  of  pustules,  or 
acervuli,  especially  localized  upon  the  veins  of  both  the  upper  and 
lower  leaf  surfaces.  Ovate  conidiospores  measuring  lo  to  15/x  X  4  to  6/x 
are  formed  upon  small  colorless  conidiophores. 

The  acervuli  measure  100  to  300/x  in  diameter  and  in  moist  weather 
the  numberless  spores  are  ejected  in  creamy  masses,  or  strings.  The 
same  stage  was  known  on  the  twigs  by  the  generic  name  of  Myxosporium. 
The  Sporonema  stage  is  represented  by  the  pycnidium,  which  develops 
from  the  stroma  of  the  fungus  and  the  interior  of  the  pycnidium  is 
lined  by  inwardly  projecting  conidiophores,  which  abstrict  pycnospores. 
The  ascigeral  stage  is  found  on  old  leaves  that  have  remained  over 
winter  in  the  open,  and  it  may  appear  in  late  winter  or  early  in  the 
spring.  The  perithecia  are  not  uniform  in  size,  for  we  find  them 
measuring  in  diameter  from  150  to  250/u  with  a  beak  50  to  loo/x  long. 
The  broadly  clavate  asci  are  bent  at  right  angles  near  the  base.  They 
have  a  thickened  apex,  a  terminal  pore  with  a  surrounding  refractive 
ring  and  bear  invariably  eight  hyaline  two-celled  elliptic  ascospores. 
The  two  ascospore  cells  are  unequal  in  size,  the  larger  of  the  two  giving 
rise  to  a  germ  tube. 

Application  of  the  5-5-50  Bordeaux  mixture  to  young  shade  trees 
and  to  nursery  stock  assists  in  controlling  the  disease. 

Tobacco  {Nicotiana  tabacum,  L.) 

Root-rot  {Thielavia  basicola,  Zopf). — This  fungus  is  found  on  a 
great  variety  of  host  plants  and  its  growth  on  the  roots  of  tobacco 
may  be  taken  as  illustrative.  It  is  found  in  the  eastern  United  States 
and  in  Europe  from  England  to  Italy.  Roots  attacked  by  this  fungus 
do  not  develop  normally  and  the  roots  may  be  so  injured,  that  if  the 
plant  is  pulled  out  of  the  soil  everything  will  remain  in  the  soil  except 


DETAILED   ACCOUNT   OF    SPECIFIC   PLANT   DISEASES 


551 


the  broken  stub  of  the  main  root  system.  Nature  attempts  to  repair 
the  damage  in  the  tobacco  by  the  formation  of  a  cluster  of  new  roots, 
so  that  affected  plants  may  not  be  killed,  but  remain  in  the  stunted 
form  (Figs.  196  and  197). 

The  intercellular  mycelium  is  septate,  hyaline  at  first  and  consists 
of  narrow  hyphae.     The  fungus  produces  three  kinds  of  spores,  which 


; :  ^n^^^K; 

1 

L 

^^f  Af ' 

^ 

■Kl  ' 

A 

■r 

^m 

hI^ 

Im 

W 

^"^^^m 

1^^*^ 

0^ 

^9 

WsT-'  ■  "^ 

^^£9b 

■Bp  <t^^'^     i'; 

1 

.-1 

mi 

Fig.  196. — -Tobacco  roots  affected  by  rot  (Thielavia  basicola).  i,  Inoculated  at 
two  months;  2,  diseased  root  from  field.  {After  Gilbert,  W.  W.,  Bull.  158,  U.  S. 
Bureau  of  Plant  Industry,  1909.) 


are  according  to  Duggar  (i)  endosporous  conidia,  which  are  formed  in 
chains  in  terminal  branches,  or  clusters  of  branches.  They  are  formed 
by  basipetal  septa tion,  as  short  cylindric  cells  within  the  branch. 
The  tip  of  the  branch  is  broken  off,  and  they  are  pushed  out  by  osmotic 
force,  so  that  the  branch  has  served  as  a  spore  case.     The  hyaline 


552 


SPECIAL   PLANT   PATHOLOGY 


197. — Root-rot  fungus  {Thielavia  basicola)  in  various  stages.      {After  Gilbert, 
W.  W.,  Bull.  158,  U.  S.  Bureau  of  Plant  Industry,  1909-) 


DETAILED    ACCOUNT    OF    SPECIFIC   PLANT   DISEASES  553 

endospores  measure  10  to  20^  by  4  to  5/i.  (2)  Another  kind  of  spore  is  the 
thick-walled  chlamydospore  which  is  cylindric  in  shape,  borne  in  chains 
and  measures  about  12/x  in  width.  (3)  The  third  kind  of  spore  is  the 
ascospore,  which  is  borne  in  evanescent  asci  in  simple  perithecia.  The 
ascospores  are  unicellular  and  measure  about  12/iby  5/i. 

To  check  or  control  the  disease  sterilization  of  the  soil  has  been 
practised.  All  diseased  roots  about  the  place  should  be  destroyed  by 
fire. 

Timber 

Decay  (Stereum  frustulosum  (Pers.),  Fr.). — The  fruit  bodies  of  this 
fungus  appear  as  slightly  raised  gray  spots  thickly  placed  on  the 
surface  of  wood  and  timber  (Fig.  85).  The  fruiting  bodies  are  2 
to  5  mm.  in  diameter.  The  action  of  this  fungus  on  structural  wood  is 
characteristic,  as  it  forms  pocket-like  areas  in  the  decaying  wood, 
causing  changes  in  the  wood  fibers.  The  holes  are  more  or  less  len- 
ticular and  are  isolated  from  each  other  by  the  sound  wood.  Layers  of 
white  cellulose  fiber  line  the  margin  of  the  hole. 

Other  decay  producing  fungi  are  punk  fungus,  Fomes  igniarius 
(Figs.  ig8,  199,  200)  and  hedgehog  fungus,  Hydnum  erinaceus  (Fig. 
201). 

Dry-rot  {Merulius  lacrymans,  Schum.). — The  dry-rot  fungus  (Der 
Hausschwamm)  is  one  of  the  best-known  and  most  destructive  of  wood- 
destroying  fungi.  For  many  years,  it  was  claimed,  that  it  was  purely 
domestic  found  only  in  connection  with  the  structural  wood-work  of 
houses  and  buildings,  but  Hartig  drew  attention  to  the  fact,  that  it 
probably  exists  occasionally  in  a  state  of  nature.  Professor  von 
Tubeuf  sums  up  the  evidence  of  Hartig^  and  a  number  of  other  observers 
in  this  statement:  "Hausschwamm  ist  bisher  ganz  auffallend  selten, 
direkt  als  botanische  Raritat,  im  Walde  gefunden  worden.  Die 
wenigen  Funde,  welche  bis  jetzt  bekannt  wurden,  sind  nicht  etwa  in 
urwaldahnlichen  Forsten  gemacht,  sondern  in  der  Nahe  der  mensch- 
lichen  Kultur;  in  solchen  Waldern,  die  in  der  Nahe  grosser  Stadte 
liegen,  oder  an  Orten  in  der  Nahe  von  Waldhausem  und  von  Wegen, 

1  Mez,  Dr.  Carl:  Der  Hausschwamm  und  die  ubrigen  holzzerstorenden  Pilze 
der  menschlichen  Wohnungen,  Dresden,  1908,  page  260;  Moller,  Dr.  A.:  Haus- 
schwamm forschungen  im  amtUchen  Auftrage.  Jena,  Band  i,  1907;  Band  ii,  1909; 
Band  iii,  1909. 


554 


SPECIAL  PLANT   PATHOLOGY 


Fig.    198. — Aspen   tree   with   sevor:il    spMi-Miih^ 
Schrenk,  Hermann,  Bull.  149,  U.  S.  Bi 


I's    (if   lutiurs    igniarius.      {After   von 
■ail  of  Plant  Industry,  1909.) 


DETAILED    ACCOUNT    OF    SPECIFIC   PLANT   DISEASES  555 

zu  deren  Anlage  bearbeitetes  Holz  verwendet  wurde,  kann  die  Mog- 
lichkeit  der  Verschleppung  des  Hausschwamms  in  den  Wald.,  nicht 
bestritten  werden.'"  To  this  wild  form,  the  name  of  Meridius  Silvester 
has  been  given.  The  domestic  form  of  the  fungus  Meridius  lacry- 
mans  is  an  obligate  saprophyte.  The  spores  fall  upon  the  exposed  end 
of  a  board,  beam,  joist,  rafter,  wooden  column,  or  flooring,  which  may 
be'in  contact  with,  or  resting  on,  a  stone  foundation,  brick  wall,  or 


Fig.  199. — Cross-section  of  the  trunk  of  a  living  silver  maple  rotted  by  Fames 
igniarius.  {After  von  Schrenk,  Hermann,  Bull.  149,  U.  S.  Bureau  of  Plant  Industry, 
pi.  a,  1909.) 

earth,  which  is  slightly  damper,  if  not  in  dry  weather,  then  during 
rainy,  than  the  more  protected  part  of  the  same  piece  of  structural 
wood.  Here  the  spore  germinates  and  produces  a  mycelium,  which 
grows  inside  the  wood  from  which  it  abstracts  the  proteins  necessary 
for  its  growth  (Figs.  88  and  8g).  At  the  same  time,  it  dissolves  the 
coniferin  and  cellulose  of  the  cell-walls,  and  leaves  behind  a  brown 
residue   consisting   of   lignin,  tannin   and  oxalate  of  lime  (Fig.  88) 


556 


SPECIAL   PLANT   PATHOLOGY 


Fig.   200. — Cross-section  of  a  living  aspen  tree  iulIlJ  by  Fames  igniarius.      {After 
von  Schrenk,  Hermann,  Bull.  149,  U .  S.  Bureau  of  Plant  Industry,  pi.  it,  1909.) 


Fig  201. — Cioss-scction  of  a  li\  ing  wIiul  wak  tu'o  dct.ued  b>  Hydnum  eri- 
naceus.  {After  von  Schrenk,  Hermann,  Bull.  149,  U .  S.  Bureau  of  Plant  Industry, 
pi.  vii,  1909.) 


DETAILED    ACCOUNT    OF    SPECIFIC   PLANT   DISEASES  557 

So  long  as  sufficient  moisture  is  present,  these  substances  enable  the 
wood  to  retain  its  original  volume,  but  whenever  water  is  withdrawn 
the  wood  becomes  traversed  by  numerous  fissures  running  at  right 
angles  to  each  other,  and  frequently,  it  breaks  up  into  regular  cubes 
which  readily  crumble  away,  if  rubbed,  or  compressed,  and  a  brown 
punky  substance  is  the  result  of  the  destructive  attack  of  the  myceUum. 

When  the  opportunity  is  presented  for  the  mycelium  to  develop 
vigorously  outside  the  nourishing  substratum,  it  forms  especially  on  the 
side  of  the  joist  or  board,  which  is  facing  a  moister  air-still  chamber,  as 
under  a  porch  floor,  or  the  interior  of  some  conduit  (electric  or  other- 
wise), a  skin-Hke  layer  which  often  attains  large  proportions.  In  other 
cases,  it  may  fill  cracks,  or  other  cavities.  If  a  microscopic  examina- 
tion is  made  of  the  hyphae  of  the  dry-rot  fungus,  they  will  be  found  of 
several  kinds  showing  clamp-connections  (Schnallenbildungen),  the 
formation  of  oidia  and  the  anastomosis  of  hyphae  that  come  in  contact. 
The  hyphal  cells  are  multi-nucleate.  Three  kinds  of  structural  hyphae 
are  discernible,  viz.,  the  ordinary  thin- walled  hyphae,  the  water-con- 
ducting hyphae  of  larger  size  and  thicker  walls,  and  the  sclerenchyma- 
like  hyphae  with  very  much  thicker  walls  than  the  other  two.  The 
function  of  the  water-conducting  hyphae  will  be  explained,  if  we  examine 
the  sheet-like  mycelia,  which  cover  at  times  the  surface  of  structural 
wood.  Such  a  mycelium  will  be  found  covered  with  drops  of  extruded 
water  like  tear  drops  (hence  lacrymans  >  Lat.  lacryma,  a  tear).  This 
water  has  been  conveyed  from  the  soil,  or  damp  wall,  in  contact  with 
the  joist,  a  beam,  a  distance  sometimes  of  ten  or  twelve  feet  to  the 
drier  parts  of  the  wood*.  This  accounts  for  the  rapid  spread  of  the 
mycelium  and  its  abiHty  to  secure  enough  water  for  its  insidious  growth 
through  well-seasoned  timbers.  Sometimes  in  houses  only  a  thin  coat 
of  paint  conceals  the  destructive  work  of  the  "house-fungus."  Later  the 
fruit  bodies  appear  as  an  extended  thin  superficial  crust  of  a  brownish- 
smoke  color  covered  with  low  anastomosing  ridges  and  wrinkles,  sug- 
gesting the  surface  of  tripe,  over  which  the  hymenial,  or  basidial,  layer 
is  spread  (Fig.  89).  The  basidiospores  are  deep  yellowish-brown  in 
color  and  impart  to  the  hymenium  a  yellowish-brown  hue.  Each 
basidium  terminates  in  four  short  sterigma  which  bear  the  basidio- 
spores, which  measure  g/j.  to  i2yu  in  length  by  5.5/x  to  6.5^t  in  breadth. 
Germination  of  the  spores  is  readily  obtained. 

Kiln  drying  of  structural  wood  is  an  excellent  means  of  preventing 


558 


SPECIAL  PLANT   PATHOLOGY 


the  growth  of  the  dry-rot  fungus.  Coating  materials  should  be  avoided 
unless  the  woods  are  absolutely  dry  and  the  well-seasoned  wood  should 
be  painted  at  once  as  neglect  on  this  score  may  cause  a  lot  of  trouble. 
The  walls  on  which  timbers  are  laid  should  be  perfectly  dry. 

Sap-rot  {Daedalea  quercina  (L.)  Pers). — One  of  the  most  im- 
portant enemies  of  structural  oak,  produces  a  soft,  mushy  decay  of 
the  wood  (Fig.  202,  also  page  76). 


/mv 


m^m. 


Fig.  202. — Dadalen  quercina  destroying  a  fence  post,  Nantucket,  Aug.  23,  1915. 
Xerophytic  hoof-shaped  fruit-body  above,  mesophytic  bracket  below  in  contact 
with  the  grass. 


Violet  {Viola  spp.) 

Spot  Disease  {AUernaria  violcB  Gall.  &  Dorsett)  (Fig.  203). — 
The  wild  violets  in  the  yard  of  the  author  have  been  attacked  by 
the  spot  disease  every  year  for  the  past  six  years.  In  some  years,  the 
attack  is  more  virulent  than  in  other  years.  It  is  also  common  on  vio- 
lets grown  under  glass,  and  in  some  districts,  commercial  violet  growing 
has  been  practically  abandoned.  The  fungus  attacks  plants  that  are 
making  a  rapid  and  vigorous  growth.  The  first  spots  are  circular, 
greenish  or  yellowish  white  ones.  They  have  a  light  colored  central 
portion  surrounded  by  a  narrow  ring  of  discolored  tissue,  usually 


DETAILED   ACCOUNT   OF   SPECIFIC   PLANT  DISEASES  559 

black  or  very  dark  brown  at  first,  but  changing  to  a  lighter  shade,  as  the 
spots  grow  older.  The  first  diseased  part  of  the  leaf  looks  as  if  water- 
logged, and  in  a  few  days,  the  diseased  part  of  the  leaf  peripheral  to  the 
central  spot  fades,  or  bleaches,  to  a  yellow,  or  grayish-white.  Here 
the  disease  may  stop  and  the  plants  recover,  the  diseased  areas  separate 
from  the  healthy  tissue  and  fall  out  leaving  holes  in  the  leaves.  The 
disease  may  spread,  however,  until  the  whole  leaf  is  destroyed. 


Fig.  203. — Violet  leaves  affected  with  leaf-spot  {Allernaria  viola).  (Photo,  by 
Heald,  F.  D.  and  Wolf,  F.  A.,  Bull.  135  (Sci.  Ser.  14),  Univ.  of  Te'x..  Nov.  15, 
1909.) 

The  majority  of  the  spots  are  free  from  fungous  spores  except  under 
conditions  favorable  to  their  development.  Some  spots  produce  spores 
in  abundance,  especially  upon  the  central,  or  older  portions  of  the  spots. 
The  spores  are  borne  in  chains  on  dark  brownish  hyphas  that  arise 
from  the  diseased  surface.  The  conidiospores  are  clavately  flask- 
shaped,  muriform,  strongly  constricted  at  the  septa,  which  are  variable 


560  SPECIAL   PLANT    PATHOLOGY 

in  number,  olivaceous,  10  to  17/i  by  40  to  6ofj.,  exclusive  of  the  isthmus, 
which  is  3  to  5/i  by  3  to  25/^.^ 

To  prevent  the  disease,  only  healthy  vigorous  stock  of  known  par- 
entage should  be  grown.  These  plants  should  be  propagated  at  the 
season  most  favorable  to  the  growth  of  the  violet.  The  frames,  glass 
houses  and  conservatories  should  be  kept  scrupulously  clean. 

Wheat  {Triticum  sativum  Lam.) 

Black-rust  (Puccima  graminis,  Pers). — Before  the  rise  of  modern 
scientific  investigation  in  botany,  the  farmers  of  Germany  believed  that 
there  was  some  connection  between  the  rusted  condition  of  their  wheat 
plants  and  the  barberry  bushes  in  proximity  to  their  fields.  It  re- 
mained for  de  Bary  in  1865  to  give  scientific  demonstration  of  the  life 
cycle  of  the  rust  fungus  by  experimental  methods.  He  found  on  the 
branches  and  leaves  of  the  wheat  plant  rust-red  lines,  which  represent 
cracks  in  the  epidermis  through  which  the  summer  spores  known  as 
uredospores,  or  urediniospores,  project.  These  together  form  the  ure- 
dinial  sorus,  or  uredinium.  The  spores,  as  they  rise  from  the  inter- 
cellular mycelium  of  the  leaf,  or  stem,  are  ovate,  yellowish-brown,  spinu- 
lose  and  measure  10  to  iS/xby  20  to  35/i.  They  may  be  repeated,  as  long 
as  fresh  blades  and  branches  are  provided  for  infection  and  spread 
to  new  parts,  but  these  spores  are  specialized,  as  they  cannot  infect  any 
other  host  plant  like  oat,  rye,  barley  and  so  forth,  but  only  wheat. 
Later  the  rust-red  sori  are  replaced  by  brownish-black  sori,  which  repre- 
sent the  telium  composed  of  teliospores,  or  teleotospores,  which  project. 
The  tehospores  are  spindle-shaped,  two  celled,  thick-walled  and  deep 
brown  in  color.  They  measure  35  to  60/i  by  12  to  22^-  Germination 
consists  in  the  formation  of  a  four-celled  promycelium,orbasidium,each 
cell  of  a  stalk  gives  rise  to  a  single  sporidium,  or  basidiospore.  These  if 
blown  to  the  barbery  enter  the  barberry  leaf  by  the  formation  of  a  germ 
tube  and  the  intercellular  mycehum  develops  a  flask-shaped  pycnium 
(spermogonium)  with  small,  spore-hke  bodies  abstrictedoff  from  vertical 
hyphae  known  as  spermatia  and  aecia,  or  cluster  cups  on  the  under  leaf 
surface,  which  give  rise  to  seciospores.  These  carried  to  the  wheat 
infect  the  wheat  and  the  cycle  is  completed.  The  aeciospores  germi- 
nate irregularly  and  capriciously,  the  process  being  accelerated  to  some 

1  DoRSETT,  P.  H. :  Spot  Disease  of  the  Violet,  Bull.  23,  U.  S.  Division  of  Vegetable 
Physiology  and  Pathology,  1900. 


DETAILED    ACCOUNT    OF    SPECIFIC   PLANT   DISEASES 


561 


extent  by  chilly  nights  with  alternating  warm  days.  Cluster  cups  that 
originate  from  spores  produced  on  the  wheat  plant,  develop  aecio- 
spores,  which  will  infect  only  wheat  plants.  If  it  should  happen  that 
these  aeciospores  are  blown  to  rye,  oats,  barley  and  rye,  no  infection 
takes  place,  so  that  the  same  specialization  of  spores  form  is  noticeable 
here  as  with  the  uredospores. 

In  America,  the  barberry  shrubs  are  extremely  rare  and  to  account 
for  the  completion  of  the  life  cycle  on  this  side  of  the  Atlantic  Ocean, 

4 


Fig.  204. — Germination  of  the  chlamydospores  of  Tilletia  falens  several  days 
after  being  placed  on  moist  plaster  of  Paris  slabs,  c' ,  showing  conjugating  basidio- 
spores.      {After  Bull.  57,  Univ.  III.  Agric.  Exper.  Slat.,  March.  1909.) 

recourse  has  been  had  to  amphispores,  which  are  thick-walled  stalked 
urediniospores  produced  in  the  western  states  under  more  or  less  arid 
conditions,  but  Arthur  thinks  that  the  perennation  of  urediniospores 
alone  is  sufficient  to  explain  the  recurrence  of  the  disease  on  the  wheat 
plant  in  succeeding  years. 

It  should  be  emphasized  also  that  within  the  species  of  black  rust, 
there  exist  several  specialized  forms,  more  or  less  adopted  to  their  own 
^^6 


562 


SPECIAL   PLANT   PATHOLOGY 


host  plants  or  plants.  According  to  Eriksson,  six  forms  can  be  dis- 
tinguished in  Sweden,  namely,  tritici  (on  wheat  seldom  on  rye,  barley 
and  oat),  secalis  (on  rye,  barley  and  couch  grass),  avencs  on  oat,  orchard 
grass,  etc.),  pocB  (on  the  blue  grasses) ,  oir«  or  species  of  Aira  and  Agrostis 
on  Agrostis  canina  and  A.  stolonifera. 


Fig.  205. — Heads  of  wheat  showing  smut  (Ustilago  tritici),  and  to  the  right, 
appearance  of  smutted  stalks  at  harvest  time.  {After  Jackson,  F.  S.,  Bull.  83,  Del. 
Coll.  Agric.  Exper.  Slat.,  December,  1900.) 

Stinking-smut  {TiUetia  fa'tcns  (B.  &  C.)  Schrt.). — This  is  the  com- 
monest smut  on  wheat  in  the  United  States.  It  occurs  in  the 
wheat-growing   regions    of    Canada^    and    the    Northwest,   where   it 

1  Gussow,  H.  F.:  Smut  Diseases  of  Cultivated  Plants.  Bui.  73,  Division  of 
Botany,  Central  Experimental  Farm,  Ottawa,  Canada,  March,  19 13. 


DETAILED    ACCOUNT    OP    SPECIFIC   PLANT   DISEASES  563 

does  considerable  damage  (Fig.  204).  The  fungus  is  confined  to 
the  wheat  plant,  although  nearly  all  the  varieties  of  that  cereal  are 
susceptible  to  it  and  under  all  climatic  conditions.  The  production  of 
spores  in  the  host  is  confined  largely  to  the  ovules,  and  as  these  begin  to 
grow,  they  become  smutted.  Such  smutted  grains  cause  a  flaring  of  the 
spikelets  and  diseased  parts  may  be  recognized  by  a  slight  difference  in 
color.  With  the  formation  of  the  spores,  a  penetrating  and  disagree- 
able odor  arises,  the  presence  of  which  gives  the  common  name  to  the 
disease.  The  smut  spores,  or  chlamydospores,  are  brown  in  color, 
nearly  spheroid  in  form  and  vary  from  16  to  25/x  in  diameter.  From 
these  chlamydospores  on  germination  acicular  or  needle-shaped  basidio- 
spores  (sporidia)  arise,  which  are  produced  in  the  form  of  a  crown  on  a 
short  basidium  (promycelium).  The  spores  may  unite  in  pairs  and 
secondary  basidiospores  be  formed. 

This  disease  can  be  controlled  by  the  use  of  formalin.  The  grain 
of  wheat  should  be  sprayed  with  the  solution  (i  pint  to  30  gallons  of 
water). 

Another  wheat  smut  fungus  is  Ustilago  tritici  (Fig.  205). 


CHAPTER  XXXVI 
NON-PARASITIC,  OR  PHYSIOLOGIC  PLANT  DISEASES 

The  non-parasitic  diseases  of  plants  traceable  to  the  unfavorable 
conditions  of  the  slope,  physical  and  chemical  character  of  the  soil  in- 
cluding the  deficiency  or  excess  of  water  content,  as  well  as  the  unfavor- 
able climatic  influences,  have  been  discussed  at  length  by  Sorauer  in 
his  "Handbuch  der  Pflanzenkrankheiten"  (3d  Edition,  assisted  by 
Lindau  and  Reh,  1908)  and  the  English  translation  of  the  3d  edition 
of  this  book  by  Frances  Dorrance  under  title  of  "  Manual  of  Plant 
Diseases,"  issued  in  parts.  Four  parts  have  already  appeared  on  Non- 
parasitic Diseases.  At  length  also  are  considered  the  poisonous  in- 
fluence of  gases  and  other  chemicals  together  with  wound  and  gall 
diseases.  Gummosis  and  several  other  physiologic  diseases  have  been 
described  by  him.  A  general  treatment  of  these  diseases  has  been 
made  in  Part  II  of  this  book  and,  therefore,  such  general  considera- 
tions need  not  be  rehearsed  here.  A  few  specific  cases  will  be  given 
by  way  of  introducing  the  student  to  another  phase  of  phytopatho- 
logic  work.^ 

It  should  be  stated  at  the  beginning  that  no  sharp  hne  can  be  drawn 
between  parasitic  and  non-parasitic  diseases.  If  they  were  controlled 
by  a  single  set  of  factors  this  might  be  done,  but  complications  always 
are  involved. 

The  classification,  however,  is  a  convenient  one  and  we  can,  there- 
fore, use  the  terms  physiologic  and  non-parasitic  merely  as  conventional 
designations  for  a  certain  class  of  diseases.  A  convenient  bibliography 
of  non-parasitic  diseases  of  plants  by  Cyrus  W.  Lantz  forms  part  of 
Circular  No.  183  Agricultural  Experiment  Station,  University  of  Illinois, 
Urbana,  May,  191 5.  The  following  are  some  of  the  names  applied  to 
such  diseases  in  the  original  papers  listed  in  the  above-mentioned 
circular  by  Lantz:  Anaheim,  Bitter-pit,  Brunissure,  Brusone,  Chloro- 

1  Smith,  R.  E.:  The  Investigation  of  Physiological  Plant  Diseases.  Phyto- 
pathology, V,  83-93,  Apr.,  191 5. 

564 


NON-PARASITIC,    OR   PHYSIOLOGIC   PLANT   DISEASES  565 

sis,  Collar-blight,  Coulure,  Court-noue,  Curly-top,  Die-back,  Exan- 
thema, Foot-rot,  Fruit-spot,  Gummosis,  Intumescence,  Leaf-curl, 
Leaf-scorch,  Mai  di  gomma,  Melanose,  Mosaic,  ffidema.  Pithiness, 
Pourriture,  Roncet,  Rosette,  Scald,  Stippen,  Sunburn,  Tipburn, 
Tomosis,  Tumor,  Water-core,  Yellows,  Zopal. 

The  following  diseases,  selected  because  of  their  interest  and  im- 
portance to  plant  growers,  may  be  looked  upon  as  belonging  to  this  class. 

Stag-head,  or  Top-dry.  The  disease  so  designated  frequently  re- 
sults from  lack  of  proper  food  in  the  soil.  The  gradual  death  of  the 
top  of  the  tree  is  an  indication  of  the  malady,  as  well  as  the  loss  of 
active  growth  in  the  lower  part  of  the  tree.  It  is  found  in  forested 
areas  where  by  burning,  or  by  denudation,  the  conditions  have  been 
changed.  Stag-head  is  frequently  seen  in  park  trees  where  the 
natural  undergrowth  has  been  removed  and  where  the  covering  of  turf 
prevents  the  access  of  rain  to  the  roots  of  the  trees,  or  where  the  stock 
of  humus  has  become  depleted  in  the  soil.  The  soil  tends  to  dry  out 
in  summer  and  in  some  of  the  parks  in  Philadelphia  its  surface  for 
several  inches  becomes  baked  hard.  This  is  assisted  by  the  constant 
tramping  of  many  feet  beneath  the  trees.  The  soil  becomes  impover- 
ished, especially  in  nitrogen  and  starvation  of  the  tree  becomes  evident 
with  the  slow  death  of  its  terminal  branches.  As  a  preventive  measure 
a  constant  supply  of  food  should  be  provided.  Wherever  practicable 
the  ground  beneath  the  tree  should  not  be  sodded  completely,  but 
should  be  planted  to  low-growing  shade-enduring  plants,  and  if  pos- 
sible, the  soil  should  be  top-worked  and  dressed  each  year  with  manure, 
or  other  plant  food.  Along  streets  and  walks  this  is  rendered  difficult 
by  the  proximity  of  paving  material,  but  as  in  Paris  each  tree  should 
have  around  its  base  an  unpaved  area  through  which  the  water  can 
seep  into  the  soil  and  by  which  plant  food  can  be  added.  An  open 
grating  can  be  placed  so  as  to  protect  the  surface  soil  about  the  tree 
from  the  tramping  of  passersby. 

Root  Asphyxiation  (Suffocation). — The  health  of  trees  and  other 
plants  depends  on  the  proper  aeration  of  the  soil.  This  is  conditioned 
on  the  size  and  proximity  of  the  soil  particles  or  the  amount  of  water 
present,  and  on  the  proximity  of  pavements,  fills  or  grading  materials, 
etc.  The  lack  of  air  is  of  far-reaching  importance.  The  organisms 
of  nitrification  cannot  carry  on  the  process  of  nitrogen  fixation  in  soils 
poor  in  oxygen,  and  this  is  true  of  wet  soils  or  those  which  are  poorly 


566  SPECIAL   PLANT   PATHOLOGY 

drained.  Flooding  of  tree  roots  is  frequently  the  cause  of  the  death 
of  the  tree.  This  is  seen  in  low  places  underlaid  by  a  hard  pan,  where 
the  groundwater  comes  close  to  the  surface,  or  in  stiff  soils,  which 
become  saturated  and  hold  their  water  for  a  long  time.  Bad  aeration 
of  the  soil  coupled  with  the  presence  of  noxious  gases  is  frequently  the 
cause  of  disease  and  death  in  street  planted  trees.  As  preventive  meas- 
ures the  ground  should  be  kept  stirred  about  the  bases  of  the  trees,  or 
where  the  ground  has  been  filled  in  around  the  tree,  small  patches  of 
bark  should  be  removed  to  induce  the  formation  of  adventitious  roots 
from  the  wounded  areas  beneath  the  new  soil  surface. 

Desiccation. — This  phenomenon  is  noticeable  in  plants  exposed  to 
bright  sunlight  following  a  spell  of  cold  or  cloudy  moist  weather.  The 
young  leaves  and  tender  shoots  of  such  plants  frequently  wither  and  die 
under  such  conditions.  This  is  sometimes  called  sun-scald,  but  evi- 
dently it  is  due  to  a  too  rapid  loss  of  water,  so  that  the  tender  parts 
wither.  The  excessive  loss  of  water  is  due  to  the  fact  that  the  leaves 
produced  in  very  moist  air  are  not  adapted  to  resist  excessive  transpira- 
tion even  where  there  is  an  abundant  supply  of  water  in  the  soil.  In 
other  words,  the  leaves  and  tender  shoots  have  not  been  sun  hardened. 
The  writer  has  noticed  such  a  state  in  the  spring  when  a  dry  hot  spell 
of  weather  succeeds  a  moist  cool  spell.  This  disease  is  produced  in  the 
West  and  Southwest  by  hot  dry  winds  which  sweep  over  the  country, 
or  in  South  Florida  by  what  are  called  dry  hurricanes.  The  "Sirocco" 
on  the  African  coast  of  the  Mediterranean  Sea,  in  Malta  and  Italy  is  a 
hot  dry  desiccating  wind,  and  so  is  the  "  Khamsin,"  a  hot  wind  from  the 
desert,  which  blows  across  Egypt.  The  leaves  of  plants  are  literally 
cooked,  or  parched,  with  such  dry  winds.  The  cold  dry  winds  of 
winter  may  produce  the  same  effects  as  the  warm  dry  ones.^ 

Remedial  measures  under  such  climatic  conditions  would  be  difficult 
to  operate.  Frequently  in  dry  regions  the  formation  of  a  dust  mulch 
by  cultivating  the  soil  surface  is  a  method  of  conserving  soil  moisture,  as 
is  also  the  application  of  litter  of  various  kinds.  Top  pruning  in  dry 
seasons  will  often  check  the  excessive  demand  for  water  and  thus  pre- 
vent injuries  to  the  rest  of  the  tree.  Copious  watering  of  the  soil 
under  such  dry  conditions  may  save  the  destruction  of  the  orchard 
trees  or  cultivated  plants.     Winter  blighting,  or  dry-out  of  coniferous 

'  Hartley,  Carl  and  Merrill,  T.  C:  Storm  and  Drouth  Injury  to  Foliage 
of  Ornamental  Trees.     Phytopathology,  V,  20-29,  Feb.,  1915. 


NON-PARASITIC,    OR   PHYSIOLOGIC   PLANT   DISEASES  567 

trees  may   be   prevented  by  proper  shelter,  or  by  liberal  mulching. 
Sometimes  a  light  straw  shelter,  or  wind-break,  may  be  efficacious. 

Water-logging. — Transpiration  from  the  leaves  of  plants  is  much 
reduced  during  periods  of  long-continued  rains  or  fogs  and  as  a  result  the 
plant  becomes  gorged  with  water.  Growth  is  stimulated,  but  the  cells 
are  thin  walled  and  easily  dry  up,  or  are  the  easy  prey  of  fungi  and  in- 
sects. Such  excess  of  water  may  result  in  the  formation  of  little  warts 
and  swellings.  These  may  be  formed  on  leaves  or  stems.  Sometimes 
the  leaves  become  diseased  by  being  water-logged  in  spots  which  are 
translucent  in  appearance.  Galloway  and  Woods^^  describe  the  in- 
fluence of  the  excess  of  water  during  the  season  of  1896  in  Washington, 
D.  C.  "  In  early  spring  vegetation  was  at  first  a  little  retarded  by  cool 
weather,  but  this  was  suddenly  followed  by  good  growing  weather, 
during  which  the  leaves  of  most  trees  and  shrubs  especially  those  of 
Norway  maples  pushed  out  with  great  rapidity.  This  latter  period  was 
followed  by  one  quite  dry  and  warm,  during  which  red  spiders  increased 
to  unusual  numbers,  particularly  on  the  lower  and  more  protected  leaves 
of  the  crown.  After  this  came  a  period  of  several  days  of  rainy  weather, 
and  many  of  the  spiders  were  washed  off,  but  the  leaves  where  they  had 
been  working  became  water-logged.  The  Norway  maples  and  horse- 
chestnuts  suffered  most,  the  leaves  of  these  trees  in  many  cases  appear- 
ing to  have  been  scorched  with  fire." 

Such  injuries  as  water-logging  resulting  from  an  excess  of  moisture 
in  the  air  cannot  be  prevented  readily.  Proper  planting  may  render 
trees  less  liable  to  such  trouble  especially  if  care  is  exercised  in  feeding 
them  after  they  are  planted.  Susceptible  trees  such  as  horse-chestnut 
and  Norway  maple  require  special  care  and  if  the  conditions  under 
which  these  trees  can  be  grown  open  the  way  to  serious  water-logging 
they  should  be  discarded  and  other  trees  planted  in  their  stead. 

Qidema  of  Manihot. — The  blister-like  pustular  outgrowths  on  plants 
variously  designated  as  oedemata  or  intumescences  have  been  the  subject 
of  careful  investigation  by  a  number  of  plant  pathologists.  The  disease 
is  also  known  as  dropsy^  and  has  been  observed  both  in  greenhouses 
and  out-of-doors  (Fig.  206).  The  diseased  condition  known  as  oedema 
or  dropsy  occurs  on  stems,  leaves  and  fruits.     It  has  been  found  recently 

^  Galloway,  B.  T.  and  Woods,  Albert  F.:  Diseases  of  Shade  and  Ornamental 
Trees.     Yearbook,  U.  S.  Dept.  Agric,  1896:  245. 

^  SoRAUER,  Paul,  Lindau,  G.  and  Reh,  L.:  Manual  of  Plant  Diseases,  trans. 
by  Frances  Dorrance,  i:  335. 


568 


SPECIAL   PLANT   PATHOLOGY 


Fig.  206. — CEdema  on  Manihot  (Ceara).  A,  Normal  arrangement  of  leaf  tis- 
sues; B,  division  and  enlargement  of  palisade  cells  in  oedematous  leaf;  C,  division  of 
cells  in  the  spongy  parenchyma  which  become  giant  cells;  D,  early  stages  of  disease 
in  which  all  of  the  cells  except  lower  epidermal  ones  are  oedematous;  E,  division  and 
enlargement  of  cells  in  lower  epidermis;  F,  cedeinatous  leaf  tissue  double  that  of 
normal  leaf;  C,  shrinking  and  collapse  of  cells  in  oedematous  leaf.  (After  Wolf  and 
Lloyd,  Phytopathology,  2:  134,  pi.  xi.) 


NON-PARASITIC,    OR    PHYSIOLOGIC    PLANT    DISEASES  569 

by  Wolf  and  Lloyd  affecting  the  leaves  of  rubber-producing  plants  be- 
longing to  the  genus  Manihot  of  which  M.  glaziovii,  M.  heptaphylla 
and  M.  pianhyensis  are  known  as  ceara.  The  leaves  of  the  ceara 
plants  growing  in  the  greenhouses  of  the  Agricultural  Experiment 
Station,  Auburn,  Alabama,  were  found  with  numerous,  glistening, 
prominently  projecting  elevations  on  either  surface  of  the  leaf.  When 
the  elevations  or  swellings  occur  on  the  upper  surface  there  are  corre- 
sponding depressions  or  concavities  on  the  lower  reaching  as  much  as 
three  millimeters  in  diameter  and  protruding  a  millimeter  above  the 
surface.  The  bUsters  are  circular  in  outline  and  mostly  isolated,  but 
if  they  exceed  300  to  500  they  become  more  or  less  confluent.  At  first 
there  is  no  change  in  the  color  of  the  leaves,  but  as  the  disease 
progresses  the  oedematous  tissue  turns  brown  and  finally  dries  and 
collapses.  The  anatomic  details  of  healthy  as  contrasted  with  the 
diseased  oedematous  cells  are  shown  in  the  accompanying  details  of 
Figure  206. 

A  number  of  explanations  have  been  given  for  the  origin  of  oedema, 
or  dropsy  in  plants.  Giant  cells  have  been  found  in  dropsical  tissues 
similar  to  those  found  in  insect  galls.  Woods  found  that  thin  walled 
oedematous  cells  were  found  in  carnations  as  a  result  of  the  puncture  by 
aphids,  and  in  such  the  possible  acid  conditions  must  be  considered. 
Sorauer  and  also  von  Schrenk  have  shown  that  intumescences  may  be 
caused  by  spraying  leaves  with  copper  salts.  Several  other  plant 
pathologists  hold  to  the  general  view  that  the  disease  is  due  to  impaired 
transpiration.  Sorauer  was  the  first  to  attribute  the  cause  to  abnormal 
elevation  of  temperature,  together  with  excessive  water  supply.  He 
finds  that  weak  light  or  semi-darkness  favors  the  accumulation  of  water 
in  the  tissues,  in  that  reduced  illumination  lowers  assimilatory  activity, 
and  swollen  tissue  results.  Viala  and  Pacollet  believe  that  brilliant 
light  is  a  prepotent  cause,  while  Fisher  argues  that  oedema  is  due  to 
the  increased  affinity  of  the  colloids  of  the  tissues  for  water.  This  may 
be  due  to  the  accumulation  of  acids  and  Wolf -and  Lloyd^  believe  that 
the  oedematous  tissue  of  ceara  seems  to  afford  some  evidence  for  the 
truth  of  this  contention. 

Frost  Necrosis  of  Potato  Tubers. — Jones  and  Bailey'' have  called  at  ten- 

'  Wolf,  Frederick,  A.  and  Lloyd,  Francis  E.:  (Edema  on  Manihot,  Phy- 
topathology 2:  131-134,  pi.  I,  191 2. 

-Jones,  L.  R.  ant)  Bailey,  Ernest:  Frost  Necrosis  of  Potato  Tubers,  Phyto- 
pathology 7:  71-72,  Feb.,  191 7. 


57©  SPECIAL   PLANT   PATHOLOGY 

tion  to  a  type  of  non-inheritable  "net  necrosis"  of  potato  tubers  which 
has  developed  under  conditions  which  suggest  frost  injury  and  this 
hypothesis  has  been  confirmed  by  chilling  experiments.  Tubers 
"frozen  solid"  are  totally  killed  and  collapse  when  thawed,  and  if  the 
chilling  stops  with  incipient  ice  crystalUzation,  such  interior  tissues  as 
are  most  sensitive  may  be  killed.  Such  frozen  tubers  are  normal  in 
external  appearance  but  when  cut  open  they  show  that  the  most 
sensitive  internal  vascular  tissues  are  discolored  and  are  killed.  There- 
fore, moderate  exposure  to  freezing  temperature  may  produce  either 
"ring"  or  "net"  necrosis,  the  blackened  vascular  tracts  penetrating  the 
fundamental  tissue  cells  filled  with  starch.  Tubers  vary  individually 
in  their  sensitiveness  but  in  general  the  best  types  of  "net  necrosis" 
have  been  secured  by  about  two  hours  exposure  to  +  5°C.  with  similar 
results  on  exposing  them  to  —  i°C.  for  eight  and  one-half  hours  to  —  9° 
C.  for  one  hour.  Slightly  more  severe  treatments,  or  unequal  exposures, 
may  give  frozen  spots  with  corresponding  dark  blotches  involving  the 
general  parenchyma.  The  stem  end  of  the  tuber  is  always  more 
sensitive  than  the  other  end. 

Apple  Fruit  Spots. — This  disease  of  the  fruit  of  the  apple  is  also 
known  as  Baldwin-spot,  bitter-pit,  fruit-pit,  pointe  bruns  de  la  chair 
and  stippen.  It  is  cosmopolitan  in  its  distribution,  being  found  wher- 
ever apples  are  grown.  It  has  recently  received  the  attention  of  a 
number  of  mycologists  and  a  number  of  explanations  as  to  its  cause  have 
been  given.  The  most  recent  study  seems  to  indicate  its  non-parasitic 
character.  The  observed  spots  are  dark  in  color,  circular  or  some- 
what angular  in  outline,  from  one-eighth  inch  or  less  to  one-fourth  inch 
in  diameter.  Although  distributed  over  the  surface  of  the  pome  they 
appear  most  commonly  on  the  blush,  or  sun-exposed  side.  A  lenticel 
forms  the  center  of  the  sHghtly  depressed  areas  or  "pocks,"  which  con- 
sist of  necrotic  tissue.  The  injury  is  superficial  extending  only  sHghtly 
into  the  pulp.  Pathologists  appear  to  have  agreed  that  the  disease  is 
due  to  extreme  variations  in  the  water-supply  of  the  apple  tree  during 
the  growing  season. 

McAlpine,^  an  Australian  mycologist,  has  published  four  quarto 

1  Eastham,  J.  W.:  Bitter  Pit  Investigation,  Phytopath.  4:  121-123,  1914 
Brooks,  Charles:  Bitter  Pit  Investigations,  Piiytopath.  6:  295-298,  1916 
Crabill,  C.  H.  and  Thomas,  H.  E.:  Stippen  and  Spray  Injury,  Phytopath.  6 
51-54,  1916. 


NON-PARASITIC,    OR   PHYSIOLOGIC   PLANT   DISEASES  57 1 

volumes  with  plates  and  illustrations  in  which  he  presents  the  evidence 
in  favor  of  the  hypothesis  that  the  stippen  is  due  to  irregularities  in  the 
factor  influencing  the  balance  between  transpiration  and  water  supply 
and  not  to  poisoning  of  cells,  e.g.,  by  arsenical  sprays  as  supported  by 
abundant  experimental  proofs.  He  beheves  that  the  principal  contrib- 
uting factors  are: 

1.  Intermittent  weather  conditions  when  the  fruit  is  at  a  critical 
period  of  growth. 

2.  Amount  and  rapidity  of  transpiration. 

3.  Sudden  checking  of  the  transpiration  at  night  when  the  roots  are 
still  active  owing  to  the  heat  of  the  soil. 

4.  Failures  of  supplies  at  the  periphery  of  the  fruit  followed  by 
spasmodic  and  irregular  recovery. 

5.  Irregularity  of  growth,  so  that  the  vascular  network  controlling 
the  distribution  of  nutritive  material  is  not  formed  regularly. 

6.  Fluctuations  in  temperature  when  fruit  is  in  store. 

7.  Nature  of  the  variety. 

Water-core  of  Apple.^ — The  diseased  fruits  are  characterized  by 
hard  watery  areas  in  the  flesh,  usually  in  the  core  and  extending  out- 
ward. Occasionally  the  flesh  is  marked  by  scattered  small  spots  with 
extensive  watery  areas  near  the  surface.  The  abnormal  areas  are 
usually  associated  with  the  vascular  tissues.  The  seed  cavities  contain 
liquid  and  the  hard  partition  membranes  become  cracked  and  covered 
with  the  hair-like  out-growth  known  as  tufted  carpels.  Norton  states 
that  the  intercellular  spaces  so  conspicuous  in  the  normal  apple 
flesh  are  filled  with  fluid  in  the  diseased  tissue  so  that  the  white  opaque 
appearance  of  the  normal  flesh  is  lacking.  "The  occurrence  of  the 
disease  under  conditions  favoring  excessive  sap  pressure  or  cell  turgor, 
on  vigorous  growing  trees,  or  trees  with  the  foliage  reduced  by  blight, 
and  especially  in  late  summer  when  the  air  is  cold  at  night  and  the  soil 
warm,  the  cracks  in  the  carpels,  the  occurrence  along  the  vascular  tissue, 
the  liquid  filling  the  intercellular  spaces,  lead  me  to  the  conclusion  that 
the  trouble  is  due  to  sap  forced  into  the  seed  cavities  and  intercellular 
spaces  by  excessive  sap  pressure  under  conditions  of  reduced  transpira- 
tion. The  air  being  excluded  from  the  inner  cells  by  the  liquid  filling 
the   intercellular  spaces,  anaerobic  respiration  may  be  increased  and 

^  Norton,  J.  B.  S.:  Water  Core  of  Apple.  Phytopathology  i:  126-128,  Aug., 
1911. 


572  SPECIAL   PLANT   PATHOLOGY 

account  for  the  alcoholic  flavor,  if  not  lead  to  the  decrease  in  acid 
and  the  sweeter  taste. 

Die-hack  or  Exanthema  of  Citrus  Fruits.^ — Exanthema  is  a  disease 
of  the  orange  groves  of  the  United  States  occurring  in  California  and 
Florida.  It  affects  all  varieties  of  the  genus  Citrus,  both  young  and 
old  trees  being  susceptible.  The  malady  is  worse  in  trees  which  grow  in 
poorly  drained  soils  underlaid  by  an  impermeable  ferruginous  sandstone 
but  it  occurs  in  hammocks  as  well.  Exanthema  attacks  the  small 
branches  and. shoots,  though  the  fruit  shows  symptoms  of  diagnostic 
value.  The  disease  is  diagnosed  more  surely  when  the  shoots  become 
more  or  less  stained  sub-epidermally  by  a  yellowish-brown  material 
and  begin  to  die  back.  The  fruit  may  become  similarly  stained  and 
its  epidermis  so  dry  that  it  cracks  and  splits  by  the  pressure  of  the 
developing  pulp  cells.  The  disease  may  be  held  in  abeyance  for  a 
number  of  years,  but  if  it  progresses,  the  shoots  swell  at  the  nodes, 
infrequently  along  the  internodes  and  as  they  mature,  Hnear,  erumpent 
pustules  break  out  on  the  internodes.  On  the  older  branches  the 
pustules  may  be  extremely  numerous  and  a  small  amount  of  gum  may 
be  observed  in  them.  Proliferation  of  young  buds  takes  place  and  these 
may  develop  into  short  branches  with  chlorotic  foliage  producing  a 
pseudo  witches'  broom. 

Exanthema  is  induced,  like  gummosis,  by  the  concurrence  of  active 
growth  and  active  tissues.  "The  soils  in  which  exanthema  occur  are 
typically  dry  soils,  which  when  saturated  by  irrigation  water  or  rains, 
promptly  become  dry  once  more  when  the  weather  clears  or  irrigation 
is  discontinued.  The  rings  of  growth,  which,  as  we  have  seen,  are  very 
marked  in  diseased  shoots  and  branches  of  trees  affected  by  exanthema, 
could  not  be  caused  except  by  a  more  or  less  rapid  succession  of  maxima 
and  minima  of  growth."  Obviously  as  climatic  conditions  cannot  be 
said  to  be  causative,  we  must  look  to  changes  in  the  water  relations  of 
the  "plants  which  causes  a  marked  development  of  the  rings  of  growth. 
Webber  and  Swingle  have  observed  that  cultivation  increases  the  sus- 
ceptibility of  the  Citrus  trees  to  exanthema,  and  even  causes  a 
more  virulent  outbreak  of  the  disease  in  the  affected  trees.  Any 
method  of  cultivation  which  tends  to  promote  regular  instead  of  fluctu- 

1  Butler,  Ormand:  A  Study  on  Gummosis  of  Prunus  and  Citrus  with  Obser- 
vations on  Squamosis  and  Exanthema  of  Citrus.  Annals  of  Botany  25:  107-153, 
1911. 


NON-PARASITIC,    OR   PHYSIOLOGIC    PLANT   DISEASES  573 

ating  growth  may  be  regarded  as  a  preventive  or  remedial  measure. 
Drainage  may  prove  to  be  remedial  to  exanthema  which  is  only  of  one 
kind  while  there  may  be  several  kinds  of  die-back. 

Mottle-leaf. — Mottle-leaf  of  Citrus  trees  is  marked  by  the  loss  of 
chlorophyll  from  parts  of  the  leaf,  the  portions  farthest  removed  from 
the  midrib  and  larger  veins  being  first  affected.  As  the  disturbance 
progresses,  the  yellowish  spots  increase  in  size  until  the  remaining 
chlorophyll  is  found  in  narrow  areas  along  the  midrib  and  larger  veins. 
The  advanced  stages  are  distinguished  by  a  marked  decrease  in  the 
size,  quality  and  yield  of  fruit.  No  organism  has  yet  been  proved 
to  be  associated  with  mottle-leaf  which  is  common  in  the  groves 
of  southern  California.  Orchards  fertilized  with  organic  materials, 
such  as  stable  manure,  usually  showed  less  mottling  than  groves  the 
soils  of  which  were  treated  with  commercial  fertilizers.  The  results 
of  soil  analyses  show  in  the  case  of  oranges  a  marked  inverse  correla- 
tion between  the  humous  content  of  the  soil  and  the  percentage  of 
mottling,  the  latter  tending  to  diminish  as  the  humous  content  increases 
and  experiments  show  that  this  humus  should  be  well  decomposed. 
It  would  seem,  therefore,  that  the  mottling  of  orange  leaves  in  the  areas 
studied  is  definitely  correlated  with  the  low  humous  content  of  the 
soil,  the  mottling  diminishing  as  the  humus  increases.^ 

Curly-top  of  Sugar  Beets. '^ — The  curly-top  of  sugar  beets  seems  to 
have  attracted  the  attention  of  growers  in  California  about  1898.  It 
is  distinguished  by  the  following  symptoms.  An  inward  curHng  of  the 
leaves,  a  distortion  of  the  veins  of  the  affected  leaves,  having  roots  and 
checked  growth.  It  has  caused  great  financial  loss  in  the  beet  dis- 
tricts of  the  western  United  States.  Experimental  study  of  the  disease 
shows  that  the  leaves  of  the  curly-top  plants  have  an  oxidase  content 
two  or  three  times  as  great  as  the  healthy  and  normally  developed 
ones.  It  appears  that  an  abnormal  retardation  of  growth  in  sugar 
beet  plants  is  accompanied  by  an  increase  in  the  concentration  of 
oxidases  in  the  leaves  or  a  change  in  the  juice  of  the  latter  by  which 
the  pyrogallol  oxidizing  oxidase  becomes  more  active. 

Peach  Yellows. — This  disease  which  according  to  the  early  records 

1  Briggs,  Lymax  J.,  Jensen,  C.  A.  and  McLane,  J.  W.:  Mottle-leaf  of  Citrus 
Trees  in  Relation  to  Soil  Conditions.     Journ.  Agric.  Res.  6:  721-739,  pis.  3,  1916. 

2  BuNZEL,  Herbert  H.:  A  Biochemical  Study  of  the  Curly-top  of  Sugar  Beets, 
Bull.  277,  U.  S.  Bureau  of  Plant  Industry,  1913. 


574  SPECIAL   PLANT   PATHOLOGY 

seems  to  have  spread  from  the  region  around  Philadelphia  as  a  center 
has  been  known  about  one  hundred  years.  It  is  a  contagious  disease  of 
unknown  origin.  Erwin  F.  Smith^  in  1894  gave  the  first  complete 
scientific  account  of  yellows  founded  upon  experimental  data.  He 
describes  the  symptoms  as  follows:  "Prematurely  ripe,  red-spotted 
fruits,  and  premature  unfolding  of  the  leaf  buds  into  slender,  pale 
shoots,  or  into  branched,  broom-like  growths.  The  time  of  ripen- 
ing of  premature  fruit  varies  within  wide  limits;  sometimes  it  pre- 
cedes the  normal  ripening  by  only  a  few  days,  and  at  other  times  by 
several  weeks.  The  red  spots  occur  in  the  flesh  as  well  as  on  the  skin, 
making  the  peach  more  highly  colored  than  is  natural.  The  taste  of 
of  the  fruit  is  generally  inferior  and  often  insipid,  mawkish,  or  bitter. 
Often  this  premature  ripening  is  the  first  symptom  of  yellows.  Often 
during  the  first  year  of  the  disease  this  kind  of  fruit  is  restricted  to  cer- 
tain limbs,  or  even  to  single  twigs,  which,  however,  do  not  differ  in 
appearance  from  other  limbs  of  the  tree.  The  following  year,  a  larger 
part  of  the  tree  becomes  affected  and  finally  the  whole  of  it,  the  parts 
first  attacked  now  showing  additional  symptoms,  if  they  have  not 
already  done  so.  These  symptoms  are  the  development  of  the  winter 
buds  out  of  their  proper  season.  The  buds  may  rush  into  shoots  only 
a  few  days  in  advance  of  the  proper  time  in  the  spring,  or  may  begin  to 
grow  in  early  summer,  soon  after  they  are  formed,  and  while  the  leaves 
on  the  parent  stem  are  still  bright  green.  This  is  a  very  common  and 
characteristic  symptom,  and  is  especially  noticeable  in  autumn  when  the 
normal  foHage  has  fallen.  Usually  under  the  influence  of  this  disease 
feeble  shoots  also  appear  in  considerable  numbers  on  the  trunk  and  main 
limbs.  These  arise  from  old  resting  buds,  which  are  buried  deep  in  the 
bark  and  wood  and  remain  dormant  in  healthy  trees.  Such  shoots  are 
sometimes  unbranched,  and  nearly  colorless,  but  the  majority  are  green 
and  repeatedly  branched,  making  a  sort  of  broomlike,  erect,  pale  green, 
slender  growth,  fiUing  the  interior  of  the  tree." 

Yellows  can  be  well  controlled  by  destroying  the  diseased  trees  as 
soon  as  they  show  premature  fruit,  or  shoots  with  the  narrow  yellow 
leaves.  The  best  treatment  is  to  pull  out  or  grub  out  and  burn  the  dis- 
eased trees,  and  remove  the  stumps  at  a  more  convenient  time.  This, 
however,  does  not  remove  all  source  of  infection  as  the  disease  may  pos- 
sibly spread  from  the  stumps  or  yellowed  shoots  arising  from  them. 

1  Smith,  E.  F.:  U.  S.  Farmers'  Bulletin  No.  17,  1894. 


NON-PARASITIC,    OR   PHYSIOLOGIC   PLANT   DISEASES  575 

The  next  year  young  trees  may  be  set  in  the  vacant  places,  care  being 
taken  to  obtain  trees  for  resetting  that  are  free  from  yellows. 

Tip-burn  of  Potato. — This  disease  is  also  called  leaf  burn  or  scald.  It 
occurs  in  many  parts  of  the  country  and  is  often  confused  with  early 
blight.  The  tips  and  edges  of  the  leaves  turn  brown  and  these  dis- 
colored areas  soon  become  hard  and  brittle.  The  burning  or  scalding 
may  occur  at  any  time  and  as  a  rule  is  the  result  of  unfavorable  con- 
ditions surrounding  the  plant.  Long  continued  cloudy  and  damp 
weather  followed  by  several  hot  bright  days  are  very  apt  to  result  in  the 
burning  of  the  foliage.  This  is  especially  the  case  on  soils  carrying  a 
comparatively  small  percentage  of  moisture.  When  the  weather  is 
cloudy  and  damp  the  tissues  of  the  potato  become  gorged  with  water  and 
this  has  a  tendency  to  weaken  them.  If  the  sun  appears  bright  and  hot 
when  the  leaves  are  in  this  condition  there  is  a  rapid  evaporation  of  the 
moisture  stored  up  in  their  cells.  The  evaporation  may  be  more  rapid 
than  the  supply  absorbed  by  the  roots,  and  if  this  continues  for  any 
length  of  time  the  weaker  and  more  tender  parts  first  collapse,  then 
die,  and  finally  turn  brown  and  dry  up.  Tip  burn  may  also  occur  as  the 
result  of  protracted  dry  weather.^ 

Little  of  a  specific  nature  can  be  said  as  to  the  treatment  of  this 
trouble.  The  plants  should  be  kept  as  vigorous  as  possible  by  good 
cultivation,  with  plenty  of  available  food. 

Leaf-casting. — The  fall  of  leaves  at  the  end  of  the  growing  season,  at 
the  approach  of  winter,  or  periodically  in  the  tropics  is  a  normal  result 
of  the  formation  of  an  abscission  layer.  The  premature  dropping  of 
leaves,  the  leaf-fall  in  house  plants,  the  dropping  of  flowers  and  twig 
abscission  are  all  manifestation  of  abnormal,  even  diseased  conditions. 

The  premature  dropping  of  leaves  owing  to  the  sudden  weakening  of 
functional  activities  concerns  the  plant  pathologist  and  is  known  as 
"leaf-casting."  The  dropping  of  pine  needles  is  only  one  phase  of  the 
general  phenomenon.  I  may  be  allowed  to  quote  here  from  the  English 
translation  of  the  third  edition  of  Sorauer's  "Manual  of  Plant  Diseases" 
(1:349)  by  Frances  Dorrance,  concerning  the  leaf-fall  in  house  plants. 
"Among  the  most  delicate  of  the  house  plants  belong  the  Azaleas, 
because,  as  a  rule,  they  suddenly  drop  their  leaves  in  summer,  or  in  the 
autumn;  the  broom-like  little  tree  then  at  best  develops  only  a  few  piti- 

1  Galloway,  B.  T.:  Potato  Diseases  and  their  Treatment.  U.  S.  Farmers' 
Bulletin  91,  1899. 


576  SPECIAL   PLANT   PATHOLOGY 

f ul  flowers.  Here  too  are  concerned  sharp  contrasts  occurring  suddenly. 
Either  the  plants  (usually  set  in  peat  soil)  in  summer  are  left  too  dry,  and 
later  watered  very  abundantly,  or  they  are  brought  too  suddenly  into 
the  warm  house  in  the  autum.  In  both  cases  the  leaves  are  weak  func- 
tionally and  then  their  functioning  is  increasingly  stimulated  by  the 
increased  upward  pressure  of  the  water.  If  the  transition  is  brought 
about  gradually,  the  inactive  leaf  Surfaces  would  have  time  to  resume 
their  normal  action  by  a  general  slow  increase  in  their  turgidity  and 
there  would  be  no  resultant  injury.  But,  with  the  sudden  upward 
pressure  of  the  water,  the  basal  region  alone  is  stimulated,  thus  causing 
the  development  of  the  cleavage  layer."  Here  are  briefly  a  few  of  the 
observations  of  the  writer  on  two  plants  of  Ftuhsia  brought  into  the 
house  from  out  of  doors  and  placed  in  a  window  with  a  bright  southern 
exposure.  Soon  after  removal  to  the  house  although  abundantly 
watered  the  leaves  began  to  drop  until  the  window  sill  was  covered  with 
the  litter.  New  leaves  were  constantly  formed,  but  these  in  turn 
dropped  off  and  this  phenomenon  continued  through  the  winter  until 
the  plants  were  transplanted  the  following  summer  to  garden  soil  when 
the  dropping  of  the  leaves  ceased  and  the  plants  again  became  apparently 
normal.  The  general  concensus  of  opinion  among  plant  pathologists  is 
that  the  disturbance  in  the  equilibrium  of  the  turgor  distribution  is  the 
cause  of  all  premature  dropping  of  the  leaves.  "For  house  plants  it 
may*be  recommended  as  a  fundamental  principle  that  the  plants  should 
be  subjected  gradually  to  other  vegetative  conditions,  and  the  dormant 
period,  upon  which  every  vegetative  part  enters,  should  not  be  inter- 
rupted by  an  increase  in  the  supply  of  heat  and  moisture." 

Curly-dwarf  of  Potato. — This  is  a  peculiar  disorder  characterized  by 
a  dwarfed  development  of  the  potato  plant  accompanied  by  a  curling 
and  wrinkling  of  the  foliage,  so  that  it  resembles  the  foliage  of  the  va- 
rieties of  cabbage  known  as  Scotch  Kale  and  Savoy  Cabbage.  The 
Germans  call  it  Krausel  Krankheit.  The  disease  is  manifest  in  the 
shortening  of  the  leaf  petioles,  midribs  and  veins  of  the  leaves  and  es- 
pecially in  the  nodes,  so  that  the  foliage  is  clustered  thickly.  The 
diminished  growth  of  the  veins  in  proportion  to  the  cells  of  the  funda- 
mental tissue  results  in  a  wrinkled  leaf  surface,  often  curled  downward. 
There  seems  also  a  tendency  for  the  formation  of  a  greater  number  of 
secondary  branches,  associated  with  brittle  stems.  The  color  of  the 
foliage  is  not  altered  as  it  remains  a  normal  green  except  in  very  severe 


NON-PARASITIC,    OR    PHYSIOLOGIC    PLANT    DISEASES  577 

cases,  when  it  becomes  a  lighter  green  sometimes  with  brown  or  reddish 
flecks,  where  the  tissues  are  dying.  This  malady  is  distinguished  from 
leaf-roll  by  the  bullate,  downward  curling  of  the  leaves,  the  persistence 
of  the  normal  leaf  green  and  the  general  firmness  of  the  leaves.  It 
results  in  the  reduction  in  the  yield  of  tubers,  and  in  several  cases  no 
tubers  have  been  found. 

The  nature  and  cause  of  this  disease  remain  inexplicable.  That  it  is 
an  hereditary  trouble  has  been  attested  by  German  plant  pathologists. 
The  tubers  from  diseased  hills  all  develop  into  curly-dwarfs,  while  those 
from  healthy  hills  remain  normal.  The  disease  which  is  found  in 
Europe  and  in  this  country  plays  a  large  role  in  the  deterioration  of 
potatoes.  It  seems  from  our  knowledge  of  the  disease  that  it  is  a 
physiologic  disorder  resulting  in  a  permanent  deterioration  of  the 
potato  stock.  It  may  develop  at  any  time  under  the  influence  of 
conditions  not  yet  fully  understood,  and  the  vigor  of  the  strain  is  reduced 
apparently  without  any  chance  of  its  restoration.  Perhaps  it  is  concerned 
with  the  senescence  of  the  particular  race  of  potatoes  attacked  or  in 
other  words  a  varietal  decline. 

The  disease  can  be  controlled  to  some  extent  by  selecting  tubers 
from  healthy  hills,  and  if  it  is  prevalent  in  a  field  of  potatoes,  it  would 
be  better  not  to  use  any  of  the  tubers  from  such  a  field  for  seeding 
purposes.^ 

Bean  Mosaic.- — Hundreds  of  acres  of  pea  beans  Phaseolus  vulgaris  in 
New  York  showed  the  mosaic  disease  in  191 6  and  in  some  fields  prac- 
tically every  plant  was  affected  and  these  plants  rarely  form  pods.  The 
malady  is  not  confined  exclusively  to  the  pea  beans,  but  affects  varieties 
of  dry  and  snap  beans  and  perhaps  is  the  same  disease  described  by  Mc- 
Clintock  as  attacking  pole  and  bush  lima  beans.  The  leaves  of  the 
plants  attacked  by  mosaic  show  irregular  crinkled  areas,  somewhat 
deeper  green  than  the  surrounding  yellowish-green  tissue.  The  dis- 
ease is  transmitted  through  the  seed  for  diseased  seedlings  develop 
from  bean  seeds  taken  from  mosaic  parents.  The  disorder  has  been 
induced  experimentally  by  rubbing  healthy  seedlings  with  crushed 
leaves  from  diseased  plants,  the  reaction  taking  place  four  weeks  later. 
The  first  signs  of  the  disease  are  seen  about  the  time  of  blossoming. 

1  Orton,  W.  a.:  Potato  Wilt,  Leaf  Roll  and  Related  Diseases,  Bull.  U.  S. 
Dept.  Agric.  64,  19 14. 

^  Stewart,  U.  B.  and  Reddick,  Donald:  Bean  Mosaic,  Phytopathology  7:  61. 
37 


578  SPECIAL   PLANT   PATHOLOGY 

Experimental  treatment  indicates  that  high  temperature  and  humidity 
at  the  time  of  inoculation  favor  infection. 

Mosaic  Disease  of  Tobacco} — This  disease  is  one  of  the  most  serious 
which  attacks  the  tobacco  plant.  It  is  known  locally  as  "calico," 
"gray-top,"  "mottled-top,"  "mottling"  and  "foxy"  tobacco.  The 
term  "frenching"  is  used  in  southern  tobacco  sections  to  designate 
abnormal,  sickly  plants  with  stringy,  very  thick  and  leathery  leaves 
which  may  be  mottled,  or  not.  It  is  not  known  whether  this  disease  is 
distinct  from  mosaic.  Chlorosis  has  also  been  used  for  mosaic,  as  well 
as  the  terms" brindle"  or  "mongrel."  Allard  states  that  the  mosaic  dis- 
ease of  tobacco  is  attended  with  various  physiologic  and  morphologic 
changes  in  the  leaves,  branches  and  sometimes  flowers  of  all  affected 
plants.  The  character  and  the  intensity  of  these  symptoms  vary 
greatly,  depending  upon  the  age,  habits  of  growth,  species  of  plants 
affected  and  external  conditions.  Allard  classifies  the  characteristic 
symptoms  of  mosaic,  as  follows: 

1.  Partial  or  complete  chlorosis. 

2.  Curling  of  the  leaves. 

3.  Dwarfing  and  distortion  of  the  leaves. 

4.  Blistered  or  "savoyed  "  appearance  of  the  leaves. 

5.  Mottling  of  the  leaves  with  different  shades  of  green. 

6.  Dwarfing  of  the  entire  plant. 

7.  Dwarfing  and  distortion  of  the  blossoms. 

8.  Blotched  or  bleached  corollas  (in  Nicotiana  tahacum  only). 

9.  Mosaic  sucker  growths. 

10.  Death  of  tissues  (sometimes  very  marked  in  Nicotiana  rustica). 
The  first  visible  symptom  of  mosaic  in  very  young  plants  appears  as  a 

slight  downward  curling  and  distortion  of  the  smallest  innermost  leaves, 
which  at  the  same  time  become  more  or  less  chlorotic.  Small  abnor- 
mally dark-green  spots  and  areas  appear  as  these  leaves  increase  in  size 
and  if  the  plants  are  not  crowded  these  spots  develop  rapidly  into  large, 
irregular,  crumpled  swellings  or  blisters  of  a  "savoyed"  appearance. 
The  leaves  of  these  young  plants  may  grow  to  a  disproportionate  size, 

1  Woods,  Albert  F.:  Observations  on  the  Mosaic  Disease  of  Tobacco,  Bull.  18, 
U.  S.  Bureau  of  Plant  Industry,  1902;  Chapman,  G.  H.  :  Mosaic  and  Allied  Diseases, 
Report  of  Botanist  in  25th  Annual  Report  Massachu  ^etts  Agricultural  Experiment 
Station,  1913;  Allard,  H.  A.:  The  Mosaic  Disease  of  Tobacco,  Bull.  U.  S.  Depart- 
ment Agriculture,  40,  1914. 


NON-PARASITIC,    OR   PHYSIOLOGIC   PLANT   DISEASES  579 

in  some  cases  becoming  long  and  sinuous.  As  the  plants  approach 
maturity  and  become  infected  they  develop  into  the  characteristic 
"gray-top"  or  "mottled-top."  The  incubation  period  of  10  or  15  days 
is  followed  especially  in  the  hot  sun  by  a  very  noticeable  wilting  of  the 
upper  leaves  which  become  finely  mottled.  The  motthng  is  due  to  the 
distribution  of  the  dark-green  shades  along  the  fine  anastomosing  veins, 
while  the  lighter  shades  occupy  the  small  inclosed  areas.  The  roots  of 
mosaic  plants  appear  superficially  quite  normal  but  it  is  probable  they 
are  impaired,  in  form  and  function.  It  is  however  in  the  leaves  that  the 
disease  is  most  manifest,  which  become  blotched  and  mottled  accom- 
panied by  distortions  which  produce  at  times  fantastic  leaf  forms.  The 
lamina  is  suppressed  at  times  so  that  the  leaf  is  reduced  to  a  twisted 
midrib.     Sometimes  long  sinuous  ribbon-like  leaf  blades  are  found. 

The  flowers  of  diseased  plants  are  characterized  by  the  presence  of 
the  normal  pink  color  in  lines,  specks,  or  conspicuous  blotches,  usually 
of  very  irregular  distribution.  A  rather  striking  and  symmetric  color 
character  is  the  occurrence  of  the  pink  color  as  a  fine  line  in  the  sinus  of 
each  corolla  lobe.  Some  blossoms  are  entirely  devoid  of  color  and  have 
a  blanched  appearance. 

Various  solanaceous  plants  are  susceptible  to  the  mosaic.  Such  are 
many  species  of  tobacco,  tomato  varieties.  Petunia,  two  distinct  garden 
varieties  of  Physalis,  Datura,  Hyoscyamus,  Solanum  (2  species),  and  in 
several  varieties  of  Capsicum.  It  is  probably  distinct  from  the  mosaic 
of  pokeweed. 

The  incubation  period  of  the  mosaic  disease  is  variable,  depending 
upon  conditions  favorable  or  unfavorable  to  the  growth  of  the  plants. 
Eight  days  is  the  shortest  period  recorded.  The  mosaic  virus  permeates 
all  parts  of  the  plant,  including  the  roots  and  corollas  as  well  as  the 
foliage,  but  it  does  not  infect  the  embryos  of  seed  produced  by  mosaic 
mother  plants,  and,  therefore,  such  seeds  produce  healthy  plants.  The 
sap  of  mosaic  plants  after  passing  through  a  filter  still  retains  its  infec- 
tious properties  and  mosaic  material  ground  and  dried  retained  its 
virulence  one  and  a  half  years.  The  virus  preserved  by  ether,  toluene 
and  glycerin  was  virulent  four  months  later,  as  was  also  the  original 
juice,  which  had  been  allowed  to  undergo  natural  fermentation  during 
that  time.  Certain  species  of  aphides  are  active  dissemmators  of  the 
mosaic  disease. 

"Various  theories  have  been  advanced  to  explain  the  primary  origin 


580  SPECIAL    PLANT   PATHOLOGY 

of  the  mosaic  disease  of  tobacco.  The  view  most  generally  accepted 
defines  the  disease  as  a  disturbance  of  the  enzymatic  equilibrium  in- 
duced by  unfavorable  conditions  of  growth.  An  enzymatic  disease  is 
physiological  in  its  nature,  has  its  origin  within  the  protoplasmic  com- 
plex, and  results  in  a  serious  and  sometimes  permanent  impairment  of 
the  assimilative  functions."  Although  it  has  been  shown  by  previous 
workers  that  the  oxidase  and  peroxidase  content  of  mosaic  leaves  is 
higher  than  in  normal  healthy  plants,  this  fact  alone  does  not  warrant, 
Allard  thinks,  its  being  considered  the  initial  cause  of  the  disease,  for  it 
might  well  be  an  effect  rather  than  a  cause.  It  is  true  that  physiologic 
symptoms  attend  the  mosaic  disease  such  as  chlorosis  and  various  mor- 
phologic changes  in  the  leaves,  and  hence  we  have  placed  it  among  the 
physiologic  diseases,  but  notwithstanding,  Allard  thinks,  that  parasi- 
tism accounts  for  the  primary  origin  of  the  disease  more  consistently 
than  the  enzymatic  hypothesis.^ 

BIBLIOGRAPHY  OF   NON-PARASITIC   DISEASES 

A  complete  bibliography  of  non-parasitic  diseases  up  to  May,  1915,  will  be  found 
in  Circular  183  Agricultural  Experiment  Station,  University  of  Illinois  by  Cyrus  W. 
Lantz,  81-111. 

^Additional  papers  on  mosaic  are,  as  follows:  Gilbert,  W.  W. :  Cucumber 
Mosaic  Disease,  Phytopath.  6:  143-144  with  i  plate;  Doolittle,  S.  P.:  A  new 
Infectious  Mosaic  Disease  of  Cucumber,  Phytopath.  6:  145-147;  Jaggee,  I.  C: 
Experiments  with  Cucumber  Mosaic  Disease,  Phytopath.  6:  148-151,  iqi6. 


PART  IV 

LABORATORY    EXERCISES    IN    CULTURAL 
STUDY   OF  FUNGI 

CHAPTER  XXXVII 
LABORATORY  AND  TEACHING  METHODS 

Introductory  Remarks. — -The  fourth  part  of  this  book  is  designed 
principally  to  give  directions  for  laboratory  exercises  in  mycology,' 
plant  pathology  and  the  determination  of  fungi.  The  teacher  will  find 
perhaps  more  than  can  be  covered  conveniently  in  a  year's  work,  unless 
the  number  of  hours  to  be  devoted  to  the  study  is  greater  than  usual  in 
college  or  university  work.  The  instructor  will  be  compelled  therefore 
to  make  a  selection.  There  is  provided  in  the  fourth  part  laboratory 
exercises  in  the  making  of  culture  media  and  stains,  the  methods  of 
study  of  bacteria  and  fungi,  the  manufacture  and  use  of  spray  materials 
and  keys  for  the  identification  of  different  kinds  of  fungi  for  use  as  class 
exercises  in  learning  how  to  identify  fungi  and  in  becoming  acquainted 
with  the  terms  used  in  systematic  mycology.  The  teacher  system- 
atically inclined  can  emphasize  the  taxonomic  exercises  provided  in  the 
lessons  and  appendices.  The  professor,  who  wishes  to  emphasize  the 
important  phases  of  plant  pathology,  will  find  in  the  fourth  part 
exercises  in  the  description  and  study  of  plant  diseases  and  the 
pathogenic  organisms  concerned  in  disease  production. 

The  teacher  interested  in  technique  will  find  many  lessons  which 
deal  with  that  subject,  as  also  the  apparatus  used  in  the  scientific  study 
of  the  fungi.  The  endeavor  has  been  to  appeal  to  a  larger  circle  of 
students  than  those  engaged  in  purely  pathologic  study.  The  inquirer, 
who  wishes  to  lay  a  foundation  in  technical  mycology,  will  find  much 
along  this  line  in  Part  IV  and  the  preceding  parts  of  the  book.  The 
teacher,  who  wishes  to  acquaint  himself  with  the  pedagogic  methods, 
will  find  suggestions  on  this  important  phase  of  mycology  in  the  last 
part  of  the  text.     The  mycophagist,  who  desires  to  grow  mushrooms,  will 

581 


582  LABORATORY   EXERCISES 

find  in  detail  a  method  for  doing  so,  and  lastly,  the  practical  grower  will 
find  formulse  and  methods  for  combating  the  various  fungous  and  insect 
foes  which  prey  upon  his  crops  and  which  must  be  subdued  or  held  in 
subjection. 

LESSON  1 

Micrometry.- — The  unit  of  length  used  in  microscopic  measurement  is  the  micron 
(im)  which  is  the  one-thousandth  part  of  a  millimeter  (o.ooi  mm.).  There  are 
four  kinds  of  micrometers  in  use:  the  stage,  the  eyepiece,  the  step,  the  filar,  or  cob- 
web, micrometer,  and  where  in  modern  types,  the  cobweb  is  replaced  by  a  finely 
spun  platinum  wire. 

Method  with  Stage  Micrometer.- — The  stage  micrometer  is  a  slide  with  a  scale 
engraved  on  it  divided  to  hundredths  of  a  millimeter  (o.oi  mm.)  every  tenth  line 
being  made  longer  than  the  intervening  ones,  to  facilitate  counting. 

I.  Attach  a  camera  lucida  to  the  eyepiece  of  the  microscope. 
•       2.  Adjust  the  micrometer  on  the  stage  of  the  microscope  and  accurately  focus 
the  divisions. 

3.  Project  the  scale  of  the  stage  micrometer  on  to  a  piece  of  paper  and  with  pen, 
or  pencil,  sketch  in  the  magnified  image,  each  division  of  which  corresponds  to  lo/x. 
Mark  on  the  paper  the  optic  combination  (ocular  objective  and  tube  length)  em- 
ployed to  produce  this  particular  magnification.  Do  this  for  each  of  the  possible 
combinations  of  oculars  and  objectives,  and  keep  the  scales  that  you  have  made 
for  future  work  in  measurement,  which  is  accomplished  by  projecting  the  image 
of  the  object  on  the  scale  corresponding  to  the  optic  combination  at  use  in  the 
study. 

Method  with  Eyepiece  Micrometer. — The  eyepiece  micrometer  is  a  circle  of  glass 
with  a  scale  etched  on  the  surface  and  suitable  for  insertion  inside  of  the  ocular 
used  during  the  operation  of  measurement.  The  scale  is  divided  to  tenths  of  a 
millimeter  (o.i  mm.)  or  the  entire  surface  of  the  glass  may  be  etched  with  squares 
(o.i  mm.),  the  net  micrometer. 

The  value  of  one  division  of  the  micrometer  scale  must  be  ascertained  for  each 
optic  combination  by  the  aid  of  the  stage  micrometer,  thus: 

1.  Insert  the  eyepiece  micrometer  within  the  tube  of  the  ocular  by  placing  it 
on  the  diaphragm  of  the  ocular,  and  adjust  the  stage  micrometer  by  placing  it  on 
the  stage  of  the  microscope. 

2.  Focus  the  scale  of  the  stage  micrometer  accurately;  the  lines  of  the  two 
micrometers  will  appear  in  the  same  plane.  Make  the  lines  on  the  two  micrometers 
to  parallel  each  other. 

3.  Make  two  of  the  lines  on  the  ocular  micrometer  to  coincide  with  those  bound- 
ing one  division  of  the  stage  micrometer;  this  is  effected  by  increasing  or  diminish- 
ing the  tube  length;  and  note  the  number  of  included  divisions. 

;u4.  Calculate  the  value  of  each  division  of  the  eyepiece  micrometer  in  terms  of 
by  means  of  the  following  formula:    x  =  icy. 

"Where  x  =  the  number  of  included  divisions  of  the  eyepiece  micrometer. 
y  =  the  number  of  included  divisions  of  the  stage  micrometer. 


LABORATOKY    AND    TEACHING    METHODS 


583 


5.  Nole  the  optic  combinations  used  and  keep  a  record  of  them  with  the  calcu- 
lated micrometer  value.  Repeat  for  each  of  the  other  combinations.  To  meas- 
ure an  object  by  this  method,  read  off  the  number  of  divisions  of  the  eyepiece 
micrometer  it  occupies  and  express  the  result  in  microns  by  looking  up  the  standard 
value  for  the  optic  combination  used. 

Example. — Determine  how  many  of  the  stage  micrometer  divisions  correspond 
with  the  eyepiece  micrometer  divisions.  Divide  the  first  by  the  last,  the  quotient 
will  be  the  true  value  of  the  ocular  micrometer  divisions  in  units  of  the  objective 
micrometer.  If  20  divisions  of  the  ocular  micrometer  cover  87  divisions  of  the 
stage  micrometer  then  ^%o  =  43-5  =  0.0435  mm. 

Method  uith  Filar  Micrometer  (Fig.  207). — This  consists  of  an  ocular  having  a 
fixed  wire  stretching  horizontally  across  the  field  with  a  vertical  reference  wire 


Fig.   207. — Screw  micrometer  eyepiece  (Filar  micrometer). 


adjusted  at  right  angles  to  the  first  and  a  fine  wire,  parallel  to  the  reference  wire, 
which  can  be  moved  across  the  field  by  the  action  of  the  micrometer  screw.  The 
trap  head  is  di^^ded  into  100  parts,  which  pass  successively  a  fixed  index  as  the  head 
is  turned.  A  fixed  comb  with  the  intervals  between  its  teeth  corresponding  to  one 
complete  revolution  of  the  screw  head  is  found  in  the  field.  As  in  the  previous 
method,  the  value  of  each  division  of  the  comb  scale  must  be  found  for  each  optic 
combination. 

1.  Place   the  filar  micrometer  and   the  stage   micrometer  in   their   respective 
positions. 

2.  Rotate  the  screw  of  the  filar  micrometer  until  the  movable  wire  coincides  with 
the  fi.xed  one,  and  the  index  marks  zero  on  the  screw  head. 


584 


LABORATORY   EXERCISES 


3.  Focus  the  scale  of  each  micrometer  accurately  and  the  lines  in  them  parallel. 

4.  Turn  the  micrometer  screw  until  the  movable  line  has  traversed  one  division 
of  the  stage  micrometer  note  the  number  of  complete  revolutions  (by  means  of  the 
recording  comb)  and  the  fractions  of  a  revolution  (by  means  of  scale  on  the  head 
of  the  micrometer  screw)  which  are  required  to  measure  the  o.oi  mm. 

5.  Make  several  estimations  and  average  the  results. 

6.  Note  the  optic  combination  employed  in  this  experiment  and  record  it  care- 
fully, together  with  the  micrometer  value  in  terms  of  /i. 

7.  Repeat  this  process  for  each  of  the  different  optic  combinations  and  record 
the  results. 

To  measure  an  object  by  this  method,  simply  note  the  number  of  revolutions  and 
fractions  of  a  revolution  of  the  screw,  and  express  the  result  as  microns  by  reference 
to  the  recorded  values  for  that  particular  optic  combination. 


Table  of  Micrometer  Values 


Designation  of 
objective 

Focal  length, 
mm. 

Mark  at  which 

the  draw  tube  has 

to  be  adjusted 

100  intervals  of  the  step 

micrometer  covers  as 
many  intervals  of  the  ob- 
ject micrometer  as  men- 
tioned below,     (i    interval 
equals  Moo  mm.) 

Micrometer 
value  in 
microns 

(o.ooi  mm.) 

Achromat 

ll 

42.0 

174 

300 

30.0 

I 

40.0 

154 

300 

30.0 

2 

24.0 

174 

150 

IS   0 

3 

16.2 

141 

100 

10. 0 

3a 

130 

IS9 

70 

7.0 

4 

10. 0 

168 

50 

S-o 

.       5 

5-4 

152 

30 

30 

6 

4.0 

160 

20 

2.0 

7 

30 

174 

IS 

i-S 

Water 

immersion 

10 

2.1 

165 

10 

I.O 

Oil 

1 

immersion 

K2 

1.8 

ISO 

10 

I.O 

1  The  tube  length  given  has  to  be  observed  strictly    and  this  tube  length  is 
understood  inclusive  of  the  nosepiece. 


LABORATORY   AND    TEACHING    METHODS 


58s 


Table  of  Micrometer  Values. — {Contiuued) 


Designation  of  j  Focal  length, 
objective        1  mm. 


100  intervals  of  the  step 

A/r^,i    ^t  „,\^;^u  micrometer  covers  as 

th^'e  dtw\ute'has   —/  -*— ^^  °f  ^^e  ob- 

V    u^   a-.^Z^i-Ja      I  ject  micrometer  as  men- 

to  be  adjusted       tioned  below,     (i  interval 

equals  Moo  mm.) 


Oil 

immersion 
K2ff 

Oil 
immersion 
Vie 


4.2 
3-2 
30 
2.6 
2.2 


16  mm. 

8  mm. 

4  mm. 

3  mm. 

Oil 

immersion 

2  mm. 

1.6 


Micrometer 
value  in 
microns 

(o.ooi  mm.) 


Fluorite  system 


180 
180 
152 
13s 
168 


158 


165 


Apochromats 


2.0 
i-S 

i-S 
1-5 


16.0 

128 

100 

10. 0 

8.0 

170 

40 

4.0 

4.0 

160 

20 

2.0 

30 

148 

IS 

I-S 

2  .0 

168 

1° 

I.O 

Step  Micrometer 


The  special  features  of  the  step  micrometer  (Stufenmicrometer)  are  that  ten 
intervals  constitute  one  group.  Each  group  is  marked  partly  in  white  and  partly 
in  black.  The  black  groups  are  accompanied  by  a  white  and  the  white  groups  by 
a  black  figure.  These  two  different  markings  facilitate  considerably  the  measure- 
ments of  specimens  of  the  opposite  color.  The  grouping  of  ten  intervals  to  one 
distinct  group  allows  a  rapid  and  convenient  count.  The  value  of  one  interval  of 
the  step  micrometer  is  0.06  mm. 

Directions  (Fig.  208). — Object  micrometer  i  mm.  divided  into  100  parts  to  be 


586 


LABORATORY   EXERCISES 


used.  The  step  micrometer  has  loo  intervals  distinctly  indicated  in  the  middle. 
It  is  necessary  to  find  the  number  of  intervals  of  the  object  micrometer  covered 
by  loo  intervals  of  the  step  micrometer,  viz.,  with  objective  3  (16  mm.),  at  a  tube 
length  of  141  mm.,  100  intervals  of  the  step  micrometer  cover  100  intervals  of  the 
object  micrometer,  equal  to  i  mm. 

One  interval  of  the  step  micrometer  is  as  i  :  100  =  o.oi  or  10  micra.     Micrometer 
value  =  10.      • 

With  objective  6  (4  mm.)  at  a  tube  length  of  160  mm.  100  intervals  of  the 
step  micrometer  cover  20  intervals  of  the  object  micrometer  = 
0.2  mm.  One  interval  of  the  step  micrometer  therefore  0.2  =  100 
=  0.002  or  2  micra.     Micrometer  value  2. 

This  new  micrometer  eliminates  the  time-consuming  measure- 
ment with  three  or  more  figures  after  the  old  method  and  is  still 
more  accurate. 

Comment.- — M.  Nobert  of  Griefswald  in  Prussia  engraved  lines 
more  than  100,000  to  the  space  of  an  inch. 

Laboratory  Work. — Compute  the  various  micrometric  values 
according  to  the  three  methods  outlined  above.  After  determin- 
ing these  values  for  the  various  combinations  of  which  your 
microscope  is  capable   measure  the  following  objects: 

Spores  of  black  mould,  spores  of  slime  moulds  studied,  various 
diatoms,  etc.  Practice  these  methods  until  you  have  perfected 
yourself  in  them. 

REFERENCES 


Fig.  208. — 
Scale  of  step 
micrometer. 


Beale,  Lionel  S.:  How  to  Work  with  the  Microscope,  1868  (4th 
Edition),  pp.  35-38. 

Behrens,  Julius  W.,  trans,  by  Rev.  A.  B.  Hervey:  The 
Microscope  in  Botany.  A  Guide  for  the  Microscopical 
Investigation  of  Vegetable  Substances,  Boston,  1885,  pp. 
120-133. 

DoLLEY,  Charles  S.:  Notes  on  the  Methods  Employed  in  Biolog- 
ical Studies,  1889,  pp.  18-20. 

Gage,  Simon  Henry:  The  Microscope.  An  Investigation  of  Micro- 
scopic Methods  and  of  Histology,  1899,  pp.  100-108. 


LESSON  2 


Directions  for  Plugging  Test-tubes  and  Flasks. — Before  sterilization  all  test-tubes 
and  flasks  must  be  carefully  plugged  with  cotton-wool,  and  for  this  purpose  best 
absorbent  cotton-wool  (preferably  that  put  up  in  cylindric  one-pound  cartons  and 
interleaved  with  tissue  paper)  can  be  used  (Fig.  209). 

I.  For  a  test-tube  or  a  small  flask,  tear  off  a  piece  of  cotton-wool  some  10  cm. 
ong  by  2  cm.  wide  from  the  roll. 


L/VEOJ^ATORY    AND    TEACHING    METHODS 


587 


2.  Turn  in  the  ends  neatly  and  rull  the  strip  of  wool  lightly  between  the  thumb 
and  fingers  of  both  hands  to  form  a  long  cjdinder. 

3.  Double  this  at  the  center  and  introduce  the  now  rounded  end  into  the  mouth 
of  the  tube  or  flask. 

4.  Now,  while  supporting  the  wool  between  the  thumb  and  fingers  of  the  right 
hand,  rotate  the  test-tube  between  those  of  the  left,  and  gradually 

screw  the  plug  of  wool  into  its  mouth  for  a  distance  of  about  the  r?='*^=^ 

same  length  of  wool  projecting.  "'         *  ' 

The  plug  must  be  firm  and  fit  the  tube  or  flask,  but  not  so 
tightly  that  it  cannot  be  removed  by  a  screwing  motion  when 
grasped  between  the  fourth,  or  third,  and  fourth  fingers  and  the 
palm  of  the  hand. 

Rough  Method  of  Cultivating  Bacteria  and  Fungi.— 1.  Make 
decoctions  of  split  peas,  cabbage,  lettuce,  hay,  lima  beans,  broad 
beans  and  water  lily  leaves  by  boiling  in  water.  Expose  decoc- 
tions to  air  by  placing  in  an  open  vessel.  This  gives  the 
organisms  introduced  from  the  air. 

2.  Boil  a  similar  lot  of  material  in  a  glass  flask  over  a  water 
bath.  After  material  is  thoroughly  steamed,  close  opening  of  the 
flask  with  a  cotton  plug.     Note  result. 

3.  Place  untreated  material  in  distilled  water  previously 
boiled.  Plug  the  flask  with  cotton.  This  wiU  serve  as  a  control. 
This  gives  the  organisms  introduced  on  the  material. 

Desiderata. — Flasks,  cotton,  water  bath  and  Bunsen  burner  for 
these  experiments  will  be  found  in  the  Culture  Room.  Perform 
all  experiments  there. 

Other  Materials. — Procure  a  loaf  of  dry  bread,  cut  it  into 
slices  and  place  slices  on  a  dinner  plate.  Wet  bread  until  well 
soaked  with  water,  cover  -with  a  bell  jar  provided  with  wet  filter 
paper. 


Fig. 


209.- 


Similarly  take  horse  manure,   wet  it  and  place  under  a  bell  ^Jl   °^    plugged 
jar.     Place  jars  in  a  dark  place 


with 


Inoculate  the  following  culture  potato  slant  rest- 
media  with  the  spores  of  the  various  fungi  that  grow  on  the  bread  ing  on  a  bit  of 
and  manure.     For  this  purpose,  use  a  platinum  needle  sterilized  ^lass  rod  to  keep 


in  the  Bunsen  flame. 

Culture  of  Slime  Moulds.- 


-Compare:  The   Culture  of  Did- 


ymitim  xanlhopus  (Ditmas)  Fr.  in  Synthetic  Media,  Science,  new  tube , 


XL:  791,  Nov.  27,  1914. 


LESSON  3 


the  potato  out  of 
the  water  in  the 
bottom  of  the 
{After 
Williams,  in 
Schneider,  Phar- 
maceutical Bac- 
teriology,  p.   54.) 


Microscopic  Study  of  Culture  Material. — A  study  is  to  be  made 
of  the  organisms  raised  in  the  culture  media  prepared  as  directed  in  Lesson  2. 

Hanging-drop  Preparation. — i.  Smear  a  layer  of  vaseline  (sterile)  on  the  upper 
surface  of  the  ring  cell  of  a  hanging-drop  slide  by  means  of  the  glass  rod  provided 
with  the  vaseline  bottle,  and  place  slide  on  a  piece  of  filter  paper. 


588  LABORATORY   EXERCISES 

2.  Flame  a  cover-slip  and  place  it  on  the  filter  paper  on  which  rests  the  hanging- 
drop  slide. 

3.  Place  a  drop  of  water  on  the  center  of  the  cover-glass  by  means  of  the  platinum 
loop. 

4.  Remove  some  of  the  material  in  the  culture  flasks  by  means  of  a  platinum  loop 
and  mix  it  with  the  drop  of  water  on  the  cover-slip. 

5.  Raise  the  cover-glass  with  the  points  of  a  forceps  and  rapidly  invert  it  on  to 
the  ring  cell  of  the  hanging-drop  slide,  so  that  the  drop  of  fluid  occupies  the  center 
of  the  ring.  (In  exact  investigation,  carefully  avoid  contact  between  the  drops  of 
fluid  and  either  the  ring  cell  or  the  ring  of  vaseline.  Should  this  happen,  the  in- 
fected hanging-drop  slide  and  its  cover-slip  must  be  dropped  into  lysol  solution  and 
a  new  preparation  made.) 

6.  Press  the  cover-slip  firmly  down  into  the  vaseline  on  to  the  top  of  the  ring  cell. 
This  spreads  out  the  vaseline  into  a  thin  layer,  and  besides  ensures  the  adhesion 
of  the  cover-slip  seals  the  cell  and  almost  prevents  evaporation. 

7.  Examine  microscopically  (vide  infra). 

Microscopic  Examination  of  the  Unstained  Material. — i.  Place  the  tube  of  the 
microscope  in  a  vertical  position. 

2.  .Arrange  the  hanging-drop  slide  on  the  microscope  stage  so  that  the  drop  of 
fluid  is  in  the  optical  axis  of  the  instrument,  and  secure  it  in  the  position  by  means 
of  the  spring  clips. 

3.  Use  one-sixth  inch  objective,  rack  down  the  body  tube  until  the  front  lens  of 
the  objective  is  almost  in  contact  with  the  cover-slip. 

4.  Apply  the  eye  to  the  eyepiece  and  adjust  the  plane  mirror  to  the  position 
which  secures  the  best  illumination. 

5.  Rack  the  condenser  down  slightly  and  cut  down  the  aperture  of  the  iris 
diaphragm  so  that  the  light,  although  even,  is  dim. 

6.  Rack  up  the  body  tube  by  means  of  the  coarse  adjustment  until  the  organisms 
come  into  view;  then  focus  exactly  by  means  of  the  fine  adjustment. 

Some  diflficulty  is  experienced  at  first  in  finding  the  hanging-drop,  and  if  the  first 
attempt  is  unsuccessful,  the  student  must  not  on  any  account,  while  still  applying 
his  eye  to  the  eyepiece,  rack  the  body  tube  down,  for  by  doing  so  there  is  every  chance 
of  breaking  the  cover-glass  and  contaminating  the  objective. 

The  examination  of  fresh  material  in  a  hanging-drop  is  directed  to  the 
determination  of: 

1.  The  nature  of  the  bacteria  and  other  organisms  present. 

2.  The  purity  of  the  culture. 

3.  The  presence  or  absence  of  motility. 

"When  the  examination  is  completed  and  the  specimen  finished  the  slide  with 
cover  slip  should  in  the  study  of  contagious  material  be  dropped  into  the  lysol  pot. 

Cf.  KissKALT,  K.:  Prakticum  der  Bakteriologie  und  Protozoologie,  Zweite 
Auflage,  Erster  Teil  (Bakteriologie),  pp.  10-12  (1909). 

Mounting  and  Staining. — The  mounting  and  staining  of  bacteria,  protozoa  and 
other  microorganisms  may  be  accomplished  as  follows: 

I.  Take  the  square,  or  round  cover-slip,  which  has  been  previously  cleaned  out 
of  the  alcohol  pot,  dry  it  between  filter  paper. 


LABORATORY    AND    TEACHING    METHODS  589 

2.  Hold  it  in  the  bacteriologic  forceps  which  are  so  constructed  that  a  spring 
holds  the  cover-slip  firmly,  while  an  enlargement  of  the  wire  handle  permits  the 
placing  of  the  forceps  on  the  table  while  the  culture  ma^terial  is  obtained. 

3.  Place  several  drops  of  distilled  water  on  the  cover-slip  and  add  a  loopful  of 
the  organisms  secured  from  the  culture  media  as  described  in  this  lesson  and  from 
the  pure  culture  in  a  test-tube  as  follows: 

4.  Remove  the  cotton  plug  by  the  third  and  fourth  fingers  of  the  left  hand. 

5.  Hold  the  open  test-tube  between  the  thumb  and  forefinger  of  the  left  hand. 

6.  By  means  of  a  previously  flamed  platinum  needle  remove  a  little  of  the 
culture  from  the  surface  of  the  culture  media. 

'/.  Replace  the  cotton  plug. 

8.  Add  the  culture  material  to  the  drop  of  distilled  water  on  the  cover-slip 
and  distribute  this  material  by  stirring. 

9.  Evaporate  the  water  on  the  cover-slip  to  dryness  by  holding  it  some  distance 
above  the  Bunsen  flame  and  slowly  enough  to  prevent  convection  circles  being  formed 
by  the  material  affixed  to  the  cover. 

10.  Pass  the  cover-glass  three  times  rapidly  through  the  Bunsen  flame. 

11.  Apply  the  stain,  which  should  remain  long  enough  to  stain  the  objects. 
The  stains  to  be  used  are  described  in  detail  below. 

12.  Wash  off  the  stain  with  distilled  water  either  from  a  wash  bottle,  or  from 
a  bottle  suspended  some  distance  above  the  laboratory  table. 

13.  Dry  between  filter  paper. 

14.  Apply  a  drop  of  balsam,  turn  the  cover-slip  over  and  drop  it  into  the  center 
of  a  glass  slide  previously  provided  and  cleaned  for  the  purpose. 

Stains. — One  of  the  most  useful  bacteriologic  stains  is: 
Ziehl's  Carbol  Fuchsin,  prepared  as  follows: 

Fuchsin  (basic) i 

Absolute  alcohol 10 

Carbolic  acid  (5  per  cent,  solution  in  water) 100 

The  fuchsin  should  be  dissolved  first  in  the  alcohol  and  then  the  two  fluids 
mi.xed. 

Loeffler's  Alkaline  Melhylcne  Blue. — ■ 

Alcoholic  solution  of  methj-lene  blue  (saturated) 3c 

Caustic  potash       i      \ 100 

Distilled  water  10,000  / 

This  fluid  retains  its  valuable  properties  for  a  considerable  time  and  is  an 
excellent  stain. 

Ehrlich's  AniUn-watcr  Gentian  Violet. 

Alcoholic  solution  of  gentian  violet  (saturated) 5 

Anilin  water 100 

This  should  be  used  as  soon  as  prepared.     It  does  not  keep  well. 


590  LABORATORY   EXERCISES 

Rhdich-Weigcrl  Anil  in  Methyl  ViolcL 

Alcoholic  solution  of  methyl  violet  (saturated) 1 1 

Absolute  alcohol ic 

Anilin  water i  oo 

This  preparation  does  not  keep  well. 

Gram's  Stain. — This  is  a  method  of  differential  bleaching  after  a  stain.  The 
cover-glass  preparations,  or  sections,  are  passed  from  absolute  alcohol  into  Ehrlich's 
anilin  gentian  violet,  or  into  a  water>  solution  of  methyl  violet,  where  they  remain 
one  to  three  minutes,  except  tubercle  bacilli  preparations,  which  remain  commonly 
twelve  to  twenty-four  hours  (Gram).  They  are  then  placed  for  one  to  three  minutes 
(occasionally  five  minutes)  in  iodine  potassium  iodide  water  (iodine  crystals,  potassic 
iodide  2  gr.,  water  300  c.c),  with  or  without  first  washing  lightly  in  alcohol.  In 
this  way  they  remain  one  to  three  minutes.  They  are  then  placed  in  absolute  alcohol 
until  sufliciently  bleached,  after  which  they  are  cleared  in  clove  oil  and  mounted 
in  Canada  balsam.  By  this  method  the  stain  is  removed  from  some  kinds  of  bacteria 
and  not  from  others.  Too  much  confidence  must  not  be  placed  in  this  method,  since 
in  some  cases  the  removal,  or  non-removal  of  the  stain  from  the  organism  depends 
on  the  length  of  exposure  to  iodine  water.  It  would  be  better,  therefore,  to  expose 
all  for  the  same  period,  e.g.,  two  minutes. 

DelafieWs  Hematoxylin. — To  100  c.c.  of  a  saturated  solution  of  ammonia  alum 
add,  drop  by  drop,  a  solution  of  i  gram  of  haematoxylin  dissolved  in  6  c.c.  of  absolute 
alcohol.     Expose  to  air  and  light  for  one  week.     FUter. 

Add  25  c.c.  of  glycerin  and  25  c.c.  of  methyl  alcohol.  Allow  to  stand  uhtU  the 
color  is  sufficiently  dark.  Filter,  and  keep  in  a  tightly  stoppered  bottle.  The 
addition  of  the  glycerin  and  methyl  alcohol  will  precipitate  some  of  the  ammonia 
alum  in  the  form  of  small  crystals.  The  last  filtering  should  take  place  four  or  five 
hours  after  the  addition  of  the  glycerin  and  methyl  alcohol. 

The  solution  should  stand  for  at  least  two  months  before  it  is  ready  for  using. 
This  "ripening"  is  brought  about  by  the  oxidation  of  the  haematoxylin  into  haematin, 
a  reaction  which  may  be  secured  in  a  few  minutes  by  a  judicious  application  of  per- 
oxide of  hydrogen  (see  Chamberlain,  Methods  in  Plant  Histology,  p.  34). 

Safranin  Gentian  Violet. — Stain  two  to  three  days  in  safranin  (dissolve  0.5  gram 
safranin  in  50  c.c.  absolute  alcohol,  and  after  four  days  add  10  c.c.  distilled  water); 
rinse  quickly  in  water;  stain  one  to  three  hours  in  a  2  per  cent,  aqueous  solution 
of  gentian  violet,  wash  quickly  in  water.  Transfer  from  stain  to  absolute  alcohol, 
clear  in  clove  oil  and  mount  in  balsam. 

Other  useful  stains  in  mycologic  work  are  Fuchsin  and  Methyl  Green,  Fuchsin 
and  Methylene  Blue,  Eosin  Water,  Erythrosin  and  Acid  Fuchsin.  For  the  prepara- 
tion of  these  and  directions  for  using  consult  Chamberlain,  Methods  in  Plant  His- 
tology, and  other  books  on  microscopic  technique. 

Neisser's  -Stain. — To  differentiate  between  diphtheiia  bacilli  and  pseudo- 
diphtheria  bacilli. 

1.  Cultivate  the  organisms  on  fresh  Loeffier's  blood-serum  at  34°  to  35°C.  for 
ten  to  twenty  hours. 

2.  Stain  with  acid  methylene  blue  three  seconds. 


LABORATORY   AND   TEACHING   METHODS  59 I 

3.  Wash. 

4.  Stain  with  Aq.  Vesuvin  five  seconds. 

5.  Wash. 

6.  Mount. 

Diphtheria  bacillus  should  show  the  polar  granules  stained  blue  and  the  body 
brown.     Pseudo-diphtheria  show  no  polar  granules. 

AuerhacK's  Stain. — Auerbach,  Leopold:  Untersuchungen  iiber  die  Spermato- 
genese  von  Paludina  vivipara.  Jenaische  Zeitschrift  fur  Naturwissenschaft,  3c: 
405-554- 

B.  Acid  fuchsin  and  Methyl  green 

Ba.  Simultaneous. 

I     part  methyl  green   \  I. 
1000  parts  of  water 

I     part  acid  fucLsin 
1000  parts  of  water. 

To  so  grams  of  the  red  solution  add  i  drop  of  10  per  cent,  glacial  acetic  acid. 

Solution  I:  3  parts   \  ^^.^^ 


Solution  II:  acid  2  parts 

If  necessary  to  filter,  use  a  filter  paper  moistened  with  solution  i,  as  the  paper 
absorbs  the  methyl  green.  Take  slides  from  alcohol  and  stain  slides  five  to  fifteen 
minutes,  having  dried  the  glass  leaving  only  the  sections  moist  before  immersion. 
20°  to  25°  is  best  temperature;  more  heat  hastens  the  absorption  of  methyl  green, 
cold  retards  it.  Place  in  absolute  alcohol  and  destain  five  to  fifteen  minutes,  or 
even  an  hour. 

Polychrome  Methylene  Blue. — See  McFarland,  Joseph:  Pathogenic  Bacteria 
and  Protozoa,  191 2,  p.  197. 

To  a  0.5  per  cent,  aqueous  solution  of  sodium  bicarbonate  add  methylene 
blue  (B  X  or  "medicinally  pure")  in  the  proportion  of  i  gram  of  the  dye  to  100  c.c. 
of  the  solution.  Heat  the  mixture  in  a  steam  sterilizer  at  ioo°C.  for  one  full  hour 
counting  the  time  after  the  sterilizer  has  become  thoroughly  heated.  The  mixture 
is  to  be  contained  in  a  flask  of  such  size  and  shape,  that  it  forms  a  layer  not  more 
than  6  cm.  deep.  After  heating,  the  mixture  is  allowed  to  cool,  placing  the  flask 
in  cold  water,  if  desired,  and  is  then  filtered  to  remove  the  precipitate  which  has 
formed  in  it.  It  should,  when  cold,  have  a  deep  purple-red  color,  when  viewed  in 
either  layer  by  transmitting  a  yellowish  artificial  light.  It  does  not  show  this 
color,  while  it  is  warm.  To  each  100  c.c.  of  the  filtered  mixture,  add  500  c.c.  of  a 
cox  per  cent,  aqueous  solution  of  yellowish  water  soluble  eosin  and  mix  thoroughly. 
Collect  the  abundant  precipitate  which  immediately  appears  on  a  filter.  When  the 
precipitant  is  dry,  dissolve  it  in  methylic  alcohol  (Merck's  reagent)  in  the  proportion 
of  0.1  grain  to  60  c.c.  of  alcohol.  In  order  to  facilitate  the-solution,  the  precipitate 
is  to  be  rubbed  up  with  methyl  alcohol  in  a  porcelain  dish,  or  mortar  with  a  metal 
spatula,  or  pestle. 

This  alcoholic  solution  of  the  precipitate  is  the  staining  fluid.     It  should  be  kept 


592  LABORATORY   EXERCISES 

in  a  well-stoppered  bottle,  because  of  the  volatility  of  the  alcohol.  If  it  becomes  too 
concentrated  by  evaporation,  and  thus  stains  too  deeply,  or  forms  a  precipitate  on 
the  blood  smear,  the  addition  of  a  suitable  quantity  of  methylic  alcohol  will  correct 
quickly  such  fault.  It  does  not  undergo  any  other  spontaneous  change  e.xcept  that 
of  concentration  by  evapoiation. 

Differential  Staining  tf  Fitngcits  and  Host  Cells. — Another  useful  method  is  set 
forth  in  the  following: 

Vaughan,  R.  E.  :  A  Method  for  the  Differential  Staining  of  Fungous  and  Host 
Cells.     Ann.  Mo.  Bot.  Gard.,  i:  241,  242. 


LESSON  4 

Liquid  Nulrienl    Solutions. — Synthetic  culture  media   (see  Smith:  Bacteria  in 
Relation  to  Plant  Diseases,  i:  197): 
Tasteitr's  Culture  Fluid  (Yeasts) : 

Ammonium  tartrate 10  gr. 

Ashes  of  yeast 10 

Rock  candy 100 

Distilled  water                1000  c.c. 

Dissolve  cold. 

Naegeli's  Nutrient  Solution. 

Calcium  chloride o.  i  gr. 

Magnesium  sulphate 0.2 

Dipotassium  phosphate i  .0 

Ammonium  tartrate 10. o 

Distilled  water 1000. o  c.c. 

Cohn's  Nutrient  Solution. 

Distilled  water 1000. o  c.c. 

Acid  potassium  phosphate 5 .  o  gr. 

Magnesium  sulphate 50 

Neutral  ammonium  tartrate 10.0 

Potassium  chloride 0.5 

(DeBary,  p.  86,  Vorles.  liber  Bakterien,  2  Auflage). 

Raulin's  Culture  Fluid. 

Magnesium  carbonate.  .  0.40  gr. 

Ammonium  sulphate. .  .  o.  25 

Zinc  sulphate 0.07 

Ferrous  sulphate o. 07 

Potassium  silicate 0.07 


Distilled  water 

1500.00  c.c, 

Granulated  cane  sugar. 

70.00  gr. 

4.00 
4.00 

Ammonium  nitrate .... 

Ammonium  phosphate 

0.60 

Potassium  carbonate. . . 

0.60 

LABORATORY   AND    TEACHING    METHODS  593 

Ptazmcwski's  Culture  Fluid. 

Dipotassium  phosphate 5 .  o  gr. 

Magnesium  sulphate 5.0 

Ammonium  carbonate 5.0 

Calcium  chloride 0.5 

Distilled  water 1000. o  c.c. 

Dissolve  cold.     Any  desired  sugar  may  be  added  as  carbon  food. 
Adolf  Mayer's  Culture  Fluid  (Unters  ii-d.  ale.  Gahr.,  1870). 

Magnesium  sulphate 10. o  gr. 

Ammonium  nitrate 15.0 

Tri-basic  calcium  phosphate o.  i 

Potassium  phosphate 10. o 

Distilled  water , 1000. o  c.c. 

Dissolve  cold  and  add  sugar.  Add  NaCl  (3  per  cent.),  if  it  is  to  be  used  for 
luminous  bacteria,  and  an  excess  of  pure  carbonate  of  hme,  if  acid-forming  bacteria 
are  to  be  grown. 

Uschinsky's  Sclution. 

Distilled  water 1000  c.c. 

Glycerin 30-40  gr . 

Sodium  chloride 5-7 

Calcium  chloride o.  i 

Magnesium  sulphate 0.3  to  0.4 

Dipotassium  phosphate 2 .  o  to  2 . 5 

Ammonium  lactate 6-7 

Sodium  asparaginate 3-4 

Modified  Uschinsky's  Sclution. — The  modified  Uschinsky's  recommended  by 
Smith  for  use  with  starch  jelly  is  made  as  follows: 

Distilled  water  1000.00  c.c. 

Ammonium  lactate 5 .  00  gr. 

Sodium  asparaginate , 2 .  50 

Sodium  sulphate 2.50 

Sodium  chloride 2 .  50 

Dipotassium  phosphate 2  .  50 

Calcium  chloride o.oi 

Magnesium  sulphate o.oi 

Fraenkel  and  Voges'  Solution. 

Water 1000  c.c. 

Sodium  chloride 5  gr- 

Dipotassium  phosphate 3 

Ammonium  lactate 6 

Sodium  asparaginate 4 

38 


594  LABORATORY   EXERCISES 

Hygienische  Rundschau,  Bd.  iv,  1894,  p.  769. 
Fermi's  Culture  Fluid. 

Distilled  water 1000. o  c.c. 

Magnesium  sulphate o  2  gr. 

Acid  potassium  phosphate i .  o 

Ammonium  phosphate 10. o 

Glycerin 450 

This  may  be  added  to  agar  in  place  of  peptonized  beef-broth  (De  jSchweinitz) 
or  to  silicate  jelly  in  which  case  the  volume  of  water  must  be  reduced. 
Knop's  Solution. 

Calcium  nitrate  (Ca(No3)2,  gram i  .00  gr. 

Calcium  chloride  (KCl),  gram o.  25 

Magnesium  sulphate  (MgS04),  gram o.  25 

Acid  potassium  phosphate  (KH2PO4),  gram o  25 

Distilled  water,  c.c 1000.00  c.c. 

Mdisdi's  Culture  Medium  {for  luminous  bacteria). 

Water 1000.00  c.c. 

Gelatin 100.00  gr. 

Sugar 20 .  00 

Pepton 10.00 

Dipotassium  phosphate o.  25 

Magnesium  sulphate o.  25 

Enough  sodium  hydroxide  is  added  to  render  the  medium  fully  alkaline.  On 
this  substratum,  the  bacteria  grow  feebly  and  are  not  luminous  until  sodium 
chloride,  or  some  equivalent  substance,  is  added  (usually  3^  per  cent.).  Then  they 
grow  well  and  become  luminous. 

Leherle-Will  Culture  Medium  {for  Yeasts). — See  KtJSTER,  Ernst:  Kultur  der 
Mikroorganismen,  p.  143. 

CaHPOi,  gram o.  50 

K2HPO4,  grams 4-55 

MgSOi,  grams 2 .  10 

Pepton,  grams 20 .  00 

Water,  liter i .  00 

Hansen's  Culture  Media  jor  Yeasts. 

Per  cent.  Per  cent. 

Pepton I  Pepton i 

Dextrose 5  Maltose 5 

Potassium  phosphate 0.3  Potassium  phosphate 0.3 

Magnesium  sulphate 0.2  Magnesium  sulphate 0.5 


LABORATORY   AND    TEACHING    METHODS  595 

Claiibsen's  Culture  Medium  for  Pyronema  conflucns. — See  Kuster,  Ernst: 
Kultur  der  Mikroorganismen,  p.  152.  Claussen  places  in  a  Petri  dish  a  small  glass 
vessel  and  fills  this  to  the  rim  with  agar  of  the  following  formula: 

Per  cent. 

Agar 2 .  000 

Inulin  puriss 2  .  000 

KH2PO4 0.050 

NH4NO3 0.050 

MgS04 •■ o  020 

Fe3(P04)2 o.ooi 

HoO ; 95  .  000 

The  outer  free  margin  of  the  Petri  dish  is  filled  with  inulin-free  agar  to  a  similar 
height  as  in  the  inner  glass  dish.  In  the  middle  one,  spores  of  Pyronema  are  sown. 
After  a  few  days  the  fungus  will  fruit  on  the  inulin-free  substratum. 

TubeuJ's  Culture  Medium  for  Dry-rot  Fungus. — See  Kuster,  Ernst:  Kultur 
der  Mikroorganismen,  p.  154. 

Grams 

Ammonium  nitrate 10 

Potassium  phosphate 5 

Magnesium  sulphate i 

Lactic  acid 2     • 

Water 1000  c.c. 

Laboratory  Work. — Each  member  of  the  class  should  make  up  at  least  three  of 
the  above  culture  media.  In  order  to  save  material,  if  the  class  consists  of  four  to 
six  students,  the  full  amount  of  materials  can  be  used  and  the  final  amount  of  liquid 
divided  into  four  to  six  parts  for  the  experiments  of  each  member  of  the  class  with 
all  of  the  media  made  according  to  the  above  formulas.  Where  the  class  is  smaller 
than  four  students,  then  one-half,  or  one-fourth  of  the  materials  should  be  used, 
as  some  of  them  are  expensive  chemicals. 

Inoculate  all  of  the  culture  solutions  with  yeast  obtained  from  a  cake  of  Fleish- 
man's compressed  yeast.  Sterilize  the  needle  and  add  some  of  the  yeast  on  the  end 
of  the  sterile  needle.  Study  and  note  the  growth  of  the  yeast  in  the  several  culture 
media  inoculated.     Bacteria  can  also  be  used. 

Fermenting  Power  of  Different  Yeasts. — Take  a  series  of  fermentation  tubes  and 
fill  to  the  tops  of  the  upright  long  branch  with  any  of  the  liquid  culture  media  used 
especially  for  yeasts.  Inoculate  one  with  dried  yeast,  one  with  brewer's  yeast, 
one  with  compressed  yeast,  one  \vith  baker's  yeast  and  others  with  several  of  the 
yeasts  kept  in  pure  culture,  and  plug  the  open  end  with  cotton.  Compare  the  de- 
pression of  the  upright  column  of  liquid  in  the  different  fermentation  tubes  in  order 
to  determine  the  relative  amount  of  gas  formed. 


59^  LABORATORY   EXERCISES 

Rani  his  Medium  for  Moidds. 

Grams 

Cane  sugar 70.00 

Tartaric  acid 4 .  00 

Ammonium  phosphate o. 600 

Magnesium  carbonate 0.400 

Ammonium  sulphate o  250 

Zinc  sulphate 0.750 

Ferrous  sulphate 0.075 

Potassium  silicate 0.070 


Water 

Too  complicated  to  be  of  much  value. 


1500.00  c.'c. 


LESSON  5 

Potatoes  as  Medium. — Whole  white  potatoes  are  taken  and  washed  with  corrosive 
sublimate  i :  1000.  They  are  then  wrapped  in  filter  paper  and  steamed  in  the 
sterilizer  about  thirty  minutes,  the  next  day  twenty  minutes,  the  third  fifteen 
minutes.  The  potatoes  are  then  cut  in  two  by  a  knife  heated  in  a  Bunsen  flame. 
The  cut  pieces  are  laid  in  a  large  fiat  glass  dish  on  a  circular  piece  of  filter  paper,  the 
glass  dishes  having  been  sterilized  by  corrosive  sublimate.  Inoculations  are  then 
made  on  the  surface  of  the  potatoes.  This  method  is  especially  useful  for  the 
growth  of  glanders,  and  chromogenic  bacteria. 

Potato  Juice. 

Grated  potato,  grams 100 

Water,  c.c 300 

Mix  and  put  in  ice  chest  over  night;  strain  off  300  c.c.  through  a  cloth.  Cook 
for  one  hour  in  water  bath,  filter  and  add  4  per  cent,  glycerin.  Sterilize.  Do  not 
neutralize  as  best  growth  of  tubercle  bacillus  is  obtained  when  the  juice  is  acid. 
Growth  is  rapid  and  luxuriant,  but  non-virulent  (Archiv  fiir  Hygiene,  XVI).  For 
culture  in  tubes  with  potatoes.  Use  knife  designed  by  Ravenel,  which  is  used  in 
the  same  manner  as  a  cork  punch  (Fig.  210).  The  semi-tubular  pieces  of  potato, 
punched  out,  are  beveled  by  a  slant  cut  and  placed  in  a  test-tube  which  is  laid 
flat  with  flat  side  of  the  potato  down  to  prevent  warping;  the  whole  is  then  sterilized 
by  the  intermittent  German  process.  After  sterilization,  it  is  sometimes  advisable 
to  add  glycerin  soaked  in  a  cotton  plug,  to  the  test-tube  in  order  to  prevent  drying. 
A  specially  designed  test-tube  (Fig.  211)  is  used  so  that  the  cut  piece  of  potato 
can  be  introduced  at  the  top  and  the  glycerin  in  the  enlarged  bottom. 

Glycerinated  Potato. — i.  Prepare  ordinary  potato  wedges. 

2.  Soak  the  wedges  in  a  25  per  cent,  solution  of  glycerin  for  fifteen  minutes. 

3.  Moisten  the  cotton-wool  plugs  at  the  bottom  of  the  potato  tubes  with  a  25 
per  cent,  solution  of  glycerin  instead  of  plain  water. 

4.  Insert  a  wedge  of  potato  in  each  tube  and  replug  the  tubes. 

5.  Sterilize  in  the  steamer  at  ioo°C.  for  twenty  minutes  on  each  of  five  consecutive 
days. 


LABOEATORY    AND    TEACHING    METHODS 


597 


Glycerin  Potato  Broth.~i.  Take  i  kilo  of  potatoes,  wash  thoroughly  in  H2O, 
peel  and  grate  finely  on  a  bread  grater. 

2.  Weigh  the  potato  gratings,  place  them  in  a  2-liter  flask,  and  add  distilled 
water  in  the  proportion  of  i  c.c.  for  every  gram  weight  of  potato.  Allow  the  flask 
to  stand  in  the  ice  chest  for  twelve  hours. 


O 


^ 


Fig.  210. — Knife  punch  designed  to 
cut  cylinder  of  potatoes  and  other  vegeta- 
bles for  insertion  as  slant  cylinders  in 
test-tubes  as  culture  media. 


Fig.  211. — Culture  tube  with  bulb 
to  hold  glycerine  and  water  below 
slant  of  vegetable. 


3.  Strain  the  mixture  through  cheese  cloth  and  filter  into  a  graduated  cylinder. 
Note  the  amount  of  the  filtrate. 

4.  Place  the  filtrate  in  a  flask,  add  an  equal  quantity  of  distilled  water,  and 
heat  in  a  steam  sterilizer  for  an  hour. 

5.  Add  glycerin,  4  per  cent.,  mix  thoroughly  and  again  filter. 

0.   Tube  and  sterilize  in  the  steamer  at  ioo°C.  for  twenty  minutes  on  each  of 
three  consecutive  days. 


598  LABORATORY   EXERCISES 

LESSON    (i 

Solid  Vegetable  Subslance  (Fig.  210).- — These  should  consist  of  slant  cylinders 
(Fig.  211)  in  cotton-plugged  test-tubes  with  some  distilled  water  and  steamed  twenty 
minutes  at  ioo°C.  on  each  of  three  consecutive  days  or  at  the  same  temperature  for 
over  an  hour.  Discontinuous  sterilization  is  best.  The  following  are  some  of  the 
vegetable  substances  recommended: 

1.  Potato  7.  Salsify  13.  Peanuts 

2.  Sweet  potato  8.  Parsnip  14.  Brazil  nuts 

3.  Carrot  9.  Onion  15.  Apple 

4.  Sugar  beet  10.  Tulip  bulb  16.  Pear,  or  quince 
5    Turnip  11.  Banana  17.  Pineapple 

6.  Radish  12.  Coconut  18.  Macaroni 

This  list  may  be  extended  almost  indefinitely.  The  method  of  preparation  of 
these  solid  vegetable  substances  for  the  test-tubes  is  fully  described  in  Lesson  5. 

Oat  Meal. — Put  10  grams  of  oatmeal  in  looo-c.c.  Erlenmeyer  flask.     Add  200 
c.c.  of  distilled  water.     Stir  until  thoroughly  mixed  and  autoclave  for  twenty-five 
minutes  at  i20°C. 
Corn  Meal. 

10  grams  +  10  c.c.  of  water. 
10  grams  +  iS  c.c.  of  water. 
10  grams  +  20  c.c.  of  water. 

LESSON  7 

Plant  Juices  (With  and  without  the  addition  of  water). — Hay  Infusion. 

1.  Weigh  out  dried  hay,  10  grams,  chop  it  up  into  fine  particles  and  place  in  a 
flask. 

2.  Add  1000  c.c.  distilled  water,  heated  to  7o°C.  Close  the  flask  with  a  solid 
rubber  stopper. 

3.  Macerate  in  a  water  bath  at  6o°C.  for  three  hours. 

4.  Replace  the  stopper  by  a  cotton  plug,  and  heat  in  the  Arnold  sterilizer  at 
ioo°C.  for  an  hour. 

5".  Filter  through  filter  paper. 

6.  Tube  and  sterilize  in  the  Arnold  sterilizer  at  ioo°C.  for  one  hour  on  each  of 
three  consecutive  days. 
Orange  Juice. 

1.  With  a  wooden,  or  metal  lemon-squeezer  remove  the  juice  from  one  or  several 
oranges  according  to  requirements. 

2.  Filter  through  ordinary  filter  paper. 

3.  Add  to  the  test-tubes  provided  for  the  purpose. 

4.  Plug  the  test-tubes  with  cotton. 

5.  Sterilize  on  three  consecutive  days. 


LABORATORY   AND   TEACHING   METHODS 


599 


Prime  Juice. 

1.  Take  a  dozen  or  two  of  prunes  and  boil  them  in  water  until  the  water  is  decid- 
edly colored  with  the  prune  extract. 

2.  Add  this  prune  juice  to  test-tubes  and  plug. 

3.  Sterilize  on  three  consecutive  days. 

Coconut  Water. — This  is  removed  directly  from  the  nut  to  sterile  test-tubes  by 
means  of  sterile  pipettes,  which  are  useful  in  many  ways.  The  pipettes  should  be 
dry-heated  and  kept  from  contamination,  or  in  long,  narrow,  covered  tin  boxes. 

Wheat  Broth  (After  Eyre  and  Gasperini). 

1.  Weigh  out  and  mix  wheat  flour,  150  grams;  magnesium  sulphate,  0.5  gram; 
potassium  nitrate,  i  gram;  glucose,  5  grams. 

2.  Dissolve  the  mixture  in  1000  c.c.  of  water  heated  to  ioo°C. 

3.  Filter  through  filter    paper. 

4.  Fill  test-tubes  and  sterilize  on  three  consecutive  days. 

Plant  Decoctions,  or  Infusions  in  General  (After  Heald). — Liquid  media  contain- 
ing the  soluble  nutrients  derived  from  various  plant  structures  are  of  special  value 
in  dealing  with  fungi  and  may  be  used  with  bacteria,  although  they  are  not  so 
important  for  these  organisms.  By  the  selection  of  parts  of  a  host  plant  for  making 
a  medium  for  the  growth  of  the  attacking  fungus,  it  will  be  provided  with  food  nearer 
to  its  immediate  needs  than  from  the  standard  nutrient  media.  Plant  decoctions 
may  be  used  as  liquid  media,  or  they  may  serve  in  combination  with  other  media 
solidified  by  gelatin,  or  agar. 

Some  of  the  most  valuable  plant  decoctions  are  obtained  from  fruits,  seeds,  root 
parts  and  other  plant  organs.  Decoctions  may  be  made  from  fresh  plant  parts  as 
sweet  potatoes,  beets,  turnips,  carrots,  celery,  bean  pods,  plums,  apples,  etc.,  or 
dried  plants  such  as  dried  apples,  dates,  beans,  leaves,  etc. 

In  preparing  either  decoctions,  or  infusions,  it  is  well  to  h'ave  the  parts  employed 
in  a  finely  divided  state.  The  parts  may  be  run  through  a  food  chopper  or  ground 
finely  by  a  small  coffee  mill.  The  pharmaceutic  standard  should  be  selected  for 
decoctions  and  infusions,  i.e.  1000  c.c.  should  contain  the  soluble  constituents  of 
50  grams  of  dry  weight  of  the  product  employed.  To  secure  uniformity  of  compo- 
sition the  following  table  can  be  used  in  determining  the  weight  of  the  fresh  product 
to  be  employed. 

Table  to  Determine  Amount  or  Dry  Substance  to  be  Used 


Name  of  plant  organ 


Potato ! 

Sugar  beet 

Carrot 

Celery 

Leaves  (young 

Leaves  (mature) 

Bark  (fresh) 

Bark  (air  dry) 


Water 
content, 

Dry 

substance, 

per  cent. 

per  cent. 

75 

25 

82 

18 

87 

13 

84 

16 

75 

25 

55 

45 

15 

85 

7 

93 

Approximate  weight 
yielding  50  grams  of 
dry  substance,  grams 


200 
27s 
390 
315 
200 


6oO  LABOKATORY   EXERCISES 

Directions  for  Making  Plant  Infusion. 

1.  Add  looo  c.c.  of  boiling  distilled  water  to  50  grams  dry  weight  of  the  sub- 
stance of  the  equivalent,  chopped  or  ground  fine. 

2.  Macerate  in  a  closed  vessel  for  thirty  minutes. 

3.  Strain  through  cheese  cloth  or  filter  as  for  other  media  and  pass  distilled  water 
through  the  filter  to  make  1000  c.c.  If  a  clear  medium  is  desired  the  white  of  an 
egg  may  be  added: 

Directions  for  Making  a  Plant  Decoction. 

1.  Add  1000  c.c.  of  cold  distilled  water  to  50  grams  dry  weight  of  the  substance, 
or  the  equivalent,  chopped  or  ground  fine. 

2.  Heat  in  a  cooker  over  a  gas  burner  and  boil  for  fifteen  minutes,  stirring  suffi- 
ciently to  prevent  burning. 

3.  Filter  as  for  infusion  and  clear,  if  desirable.  Decoctions  are  preferable  to 
infusions  since  there  will  be  a  somewhat  more  complete  extraction  of  the  nutrients. 

Laboratory  Study.— In  the  use  of  the  culture  fluids  observe  the  rapidity,  density 
and  persistency  of  the  growth.  Record  the  formation  of  acids,  alkalis,  odors,  gas 
bubbles,  stains,  etc. 

LESSON   8 

Milk. — Nearly  all  bacteria  grow  in  milk.  Ordinary  cow's  milk  is  used.  The 
cream  is  separated  off  and  the  skim  milk  used.  Ordinary  milk  as  sold  is  contami- 
nated with  fecal  bacteria,  those  found  in  cow's  dung  and  around  stables.  Conse- 
quently the  milk  before  it  is  used  must  be  thoroughly  sterilized.  It  may  be  used 
in  this  form,  or  a  tincture  of  blue  litmus  is  added  until  a  pale  blue  color  is  obtained. 
Different  organisms  react  differently  with  this  milk;  some  render  the  litmus  more 
deeply  blue,  others  are  indifferent,  some  give  an  acid  reaction. 

The  milk  should  not  be  acid  to  taste  and  should  not  contain  formaldehyd,  or 
other  antiseptic  substance  which  milk  dealers  sometimes  add  to  milk  to  improve  its 
keeping  qualities.  It  should  be  steamed  in  wire-crates  fifteen  minutes  at  ioo°C. 
on  each  of  four  consecutive  days  (loo-c.c.  portions  in  test-tubes)  and  should  not  be 
used  until  at  least  a  week  after  the  last  steaming.  Such  milk  should  be  kept  under 
observation  at  least  si.x  or  eight  weeks. 

Litmus  milk  is  prepared  from  fresh  milk  which  has  been  passed  through  a  separa- 
tor (centrifuge)  or  from  milk  which  has  stood  eighteen  or  twenty  hours  at  2o°C.  and 
has  had  the  cream  removed  by  skimming.  To  each  100  c.c.  of  this  milk  is  added 
2  c.c.  of  a  saturated  solution  of  high-grade  lime-free  blue  litmus  (litmus  i  gram,  water 
15  c.c).  This  gives  a  lavender  color  of  just  the  right  degree,  which  reddens  distinctly 
under  the  action  of  acids  and  blues  with  the  development  of  alkalis.  After  adding 
the  litmus  water,  the  milk  should  be  pipetted  in  lo-c.c.  portions  into  cotton-plugged 
test-tubes  and  heated  as  directed  above.     This  is  a  very  useful  medium. 

Litmus  Whey  (After  Eyre). 

1.  Curdle  fresh  milk  by  adding  rennet  (or  by  acidifying  with  hydrochloric  acid). 

2.  Filter  off  the  whey  into  a  sterile  flask. 

3.  Heat  in  the  Arnold  sterilizer  for  one  hour. 

4.  Filter  into  a  sterile  flask. 


LABORATORY    AND    TEACHING    METHODS  6oi 

5.  Tint  the  whey  with  litmus  solution  to  a  deep  purple  red. 

6.  Tube,  and  sterilize  as  for  milk. 

Laboratory  Study. — Milk  offered  for  sale  in  cities  is  frequently  more  than  forty- 
eight  hours  old  and  often  contains  3,000,000  to  6,000,000  bacteria  per  cubic  centi- 
meter.    Such  milk  is  not  fit  for  laboratory  use. 

Observe  in  particular: 

(o)  The  separation  of  the  casein  without  the  development  of  any  acid,  indicating 
the  presence  of  lab,  or  rennet,  ferment.     The  milk  usually  becomes  more  alkaline. 

{b)  Saponification  of  the  fat.  The  fluid  becomes  transparent  without  any  pre- 
cipitation of  the  casein;  but  the  caseinogen  may  be  thrown  down  subsequently  by 
acidifying  the  clear  liquid. 

(f)  Ropiness.     The  liquid  becomes  viscid  and  strings  when  touched. 

(</)  Formation  of  acids. 

(f)  Resolution  of  precipitated  casein  (trypsin  ferment);  formation  of  crystals, 
tyrosin,  leucin,  etc. 

{{)  Gelatinization  of  old  cultures.     Milk  alkaline. 

{g)  Changes  in  smell,  color,  taste. 

Beerwort. — Beerwort  obtained  from  the  brewery  is  put  in  test-tubes  with  cotton 
plugs.  These  test-tubes  are  then  sterilized  by  discontinuous  sterilization  and  then 
inoculated.     It  is  a  useful  medium  for  the  culture  of  yeasts. 

Beerwort  may  be  added  to  agar,  or  ia  the  cultivation  of  moulds  for  class  study 
it  may  be  used  to  soak  bread  or  other  material  on  which  the  moulds  are  to  be 
cultivated. 

LESSON  9 

Bouillon. — Bouillon  forms  the  nutrient  basis  for  culture  media.  It  is  made  up 
in  the  following  proportions,  a  certain  amount  of  water  being  used:  i  per  cent,  pep- 
tone, .5  per  cent.  NaCl  and  .5  per  cent,  beef  extract  are  added  and  the  liquid 
boiled.     Thus  for  r  liter  of  H.O 

10  grams  peptone  ] 

5  grams  salt  \  are  added. 

5  grams  beef  extract       J 

This  solution  has  a  slight  acid  reaction  and  is  neutralized  by  10  per  cent.  NaOH 
until  it  is  no  longer  acid  to  blue  litmus,  but  is  still  acid  to  phenolphtalein.  Bouillon 
is  used  either  alone  or  with  other  media  in  combination. 

Fresh  Bouillon. — Prepared  by  digesting  fresh  veal  (3  pounds)  in  water  over  night. 
This  mass  is  then  pressed  until  the  water  and  dissolved  juice  are  separated  from  the 
meat  fiber.  After  filtration,  the  liquid  is  brought  to  a  boil  and  a  coagulation  of  the 
albuminoids  present  takes  place.  The  liquid  is  again  filtered  and  is  found  to  be 
decidedly  acid.  In  one  case  it  was  found  that  3  pounds  of  veal  made  2800  c.c.  of 
liquid  beef  tea,  or  meat  extract,  which  consists  essentially  of  the  salts  of  the  meat. 
To  make  the  regulation  bouillon,  to  this  liquid  must  be  added  salt  and  peptone 
according  to  the  following  proportion.  Cllycerin  may  be  added  for  the  growth  of  the 
tubercle  bacillus. 


6o2 


LABORATORY   EXERCISES 


2800  c.c. 
38  grams 
14  grams 


Water  extract  beef 

Peptone 

Salt 


(Bouillon  alone) 


[40  c.c. 


Glycerin 


After  boiling,  to  this  is  to  be  added  enough  of  10  per  cent.  NaOH  to  neutralize 
the  acidity  of  the  meat  extract.  It  must  be  neutralized  until  it  is  alkaline  to  blue 
litmus  and  acid  to  phenolpthalein.  It  is  again  filtered  and  is  ready  for  use.  Tu- 
bercle bacilli  grow  exceptionally  well  in  this  second  solution. 

Fresh  Bouillon  (Another  formula). — Standard  peptonized  beef  bouillon  is  made 
as  follows:  To  500  grams  of  finely  minced  lean  beef  add  1000  c.c.  of  distilled  water. 


-Diagram  illustrating  construction  and  action  of  Arnold  steam  sterilizer. 
(Fig.  15,  p.  39,  Schneider,  Pharmaceutical  Bacteriology,  1912.) 


The  soluble  parts  may  be  removed  from  the  meat  by  allowing  the  water  to  stand 
on  it  for  twenty-four  hours  in  the  ice  chest  or  for  one  hour  in  the  water  bath  at  55°C. 
The  second  method  is  perhaps  preferable.  Then  boil  for  sixty  minutes  either  in  the 
steamer,  or  in  a  covered  dish.  Filter  through  clean  cloth,  using  pressure  (meat  press) , 
cool,  and  remove  fat  by  filtering  through  filter  paper;  make  up  to  1000  c.c.  by  addi- 
tion of  more  water;  then  add  i  per  cent.  Witte's  peptonum  siccum  and  0.5  per  cent, 
c.p.  sodium  chloride.  Steam  one-half  hour,  filter,  cool,  titrate,  add  required  alkali, 
steam  again  for  one-half  hour,  filter  pipette  into  test-tubes  or  flasks,  and  autoclave  or 
heat  for  a  minimum  time  in  the  Arnold  sterilizer  (Fig.  212).  Plugs  should  be  well 
made  and  fit  tightly;  glassware  should  be  scrupulously  clean.  For  some  purposes 
both  the  peptone  and  the  salt  should  be  omitted.  A  greenish  bouillon  indicates 
insufficient  boiling,  and  will  usually  throw   down   some  additional  vexatious  pre- 


LABORATORY   AND   TEACHING   METHODS  603 

cipitate  when  heated  in  the  test-tubes.     Other  meats  may  be  substituted  for  beef, 
and  other  peptones  for  Witte. 
Glycerin  Bouillon. 

1.  Measure  out  nutrient  bouillon,  looo  c.c. 

2.  Measure  out  glycerin,  60  c.c.  (  =  6  per  cent.)  and  add  to  the  bouillon. 

3.  Tube  and  sterilize  as  for  bouillon. 
Sugar  Bouillon. 

1.  Measure  out  nutrient  bouillon,  1000  c.c. 

2.  Weigh  out  glucose,  20  grams  (  =  2  per  cent.)  and  dissolve  in  the  fluid. 

3.  Tube  and  sterilize  as  for  bouillon.  Ordinary  commercial  glucose  serves  the 
purpose  equally  well,  but  it  is  not  recommended,  as  during  the  process  of  steriliza- 
tion the  medium  gradually  deepens  in  color.  In  certain  cases  a  corresponding  per- 
centage of  lactose,  maltose,  or  saccharose,  is  substituted  for  glucose. 

LESSON  10 

Egg  Albumen. — Absolutely  fresh  eggs  should  be  used.  The  end  of  the  egg  from 
which  the  albumen  is  poured  must  be  thoroughly  flamed  before  it  is  broken,  and  care 
must  be  used  in  the  transfer  to  test-tubes,  so  as  to  exclude  air-borne  germs;  other- 
wise, the  sterilization  will  be  diiificult.  By  being  placed  in  a  steam  sterilizer  and 
sterilized  by  intermittent  sterilization  for  three  days,  care  being  taken  to  leave  off  the 
cover  of  the  sterilizer  (Fig.  211),  the  albumen  will  be  found  to  be  white,  quite  hard 
and  ready  for  use.  If  the  lid  of  the  sterilizer  is  kept  on  and  the  heat  becomes  too 
great,  bubbles  will  form  in  the  albumen  and  thus  spoil  its  usefulness.  The  albumen 
of  eggs  may  be  cut  with  sterile  scissors. 

Egg  Albumen  (After  Eyre,  The  Elements  of  Bacteriological  Technique,  1902: 
160). 

1.  Break  several  fresh  eggs  (hens',  ducks',  or  turkeys'  eggs)  and  collect  the 
"whites"  in  a  graduated  cylinder,  taking  care  to  avoid  admi.xture  with  3'olks. 

2.  Add  40  per  cent,  distilled  water,  and  incorporate  the  mixture  thoroughly  by 
aid  of  an  egg  whisk. 

3.  Weigh  out  0.15  per  cent,  sodium  hydrate  and  dissolve  it  in  the  fluid  (or  add 
the  amount  of  decanormal  caustic  soda  solution  (see  infra)  calculated  to  yield  the 
required  percentage  of  soda  in  the  total  bulk  of  the  fluid — i.e.,  0.375  c.c.  of  deca- 
normal NaOH  solution  per  100  c.c.  of  the  mixture. 

3a.  Glucose  to  the  extent  of  i  or  2  per  cent,  may  now  be  aaded,  if  desired. 

4.  Strain  the  mixture  through  butter  muslin  and  filter  through  a  porcelain 
filter  candle  into  a  sterile  filter  flask. 

5.  Tube,  and  stiffen  at  ioo°C.  in  the  serum  inspissator,  or  in  the  steam  sterilizer 
with  the  lid  off. 

•  6.  Incubate  at  37°C.  for  forty-eight  hours  and  eliminate  any  contaminated  tubes; 
store  the  remainder  for  future  use. 

Egg  Yolk. — This  is  poured  into  test-tubes  and  solidified  in  a  slanting  position  bj' 
8o°C.  heat,  or  the  egg  may  be  boiled  hard  and  the  yolk  cut  with  a  sharp  knife  and 
transferred  to  sterile  petri  dishes.  If  desired  the  yolk  and  white  may  be  mixed 
before  solidifying,  i.e.  by  shaking  the  egg  vigorously  before  breaking  the  shell. 


6o4  LABORATORY    EXERCISES 

Solidified  Blood-scrum. — As  this  medium  is  rather  difficult  to  obtain  and  prepare, 
being  one  of  the  most  difficult  to  make  in  culture  work,  the  plant  mycologist  must 
in  general  obtain  blood-serum  from  the  animal  bacteriologist.  Near  Philadelphia  it 
can  be  purchased  from  the  laboratory  of  H.  K.  Mulford  &  Co.,  Glenolden,  Pa.  The 
solidified  serum  may  be  used  either  plain  or  with  the  addition  of  grape  sugar. 

Fresh  Serum  How  Obtained. — Procure  blood  by  a  sterile  method  from  a  horse, 
or  a  cow,  and  stand  it  aside  in  a  cool  place,  breaking  the  clot  from  the  side  of  the  jar 
until  the  amber-colored  serum  rises  to  the  surface,  when  it  is  to  be  drawn  off.  It 
is  then  filtered  and  measured  off.  To  3  parts  of  this  serum,  i  part  of  bouillon,  pre- 
pared in  the  ordinary  way,  is  to  be  added.  The  mixture  of  bouillon  and  serum  is 
then  to  be  filled  into  the  sterile  test-tubes,  care  being  taken  to  slant  the  tubes.  By 
being  placed  in  a  steam  sterilizer  and  sterilized  by  intermittent  sterilization  for  three 
days,  care  being  taken  to  leave  off  the  cover  of  the  sterilizer,  the  serum  will  be  found 
to  be  white  and  quite  hard  and  ready  for  use.  If  the  lid  of  the  sterilizer  is  kept  on 
and  the  heat  becomes  too  great,  bubbles  will  form  in  the  serum  and  thus  spoil  the 
usefulness  of  the  hardened  serum. 

Before  filling  the  tubes,  care  must  be  taken  that  the  mixed  serum  and  bouillon 
are  thoroughly  neutralized  by  NaOH.  As  blood-serum  is  rarely  used  in  mycologic 
work,  the  above  notes  are  given  merely  for  reference.  The  teacher  will  probably 
find  it  convenient  to  omit  this  part  of  Lesson  10  entirely. 

LESSON  11 

Nutrient  Gelatin.- — To  1000  c.c.  of  sterile  peptonized  beef-bouillon  add  100  grams 
of  best  quality  gelatin.  Soak  two  hours  at  room  temperature,  then  steam  five 
minutes,  cool,  titrate,  add  the  necessary  alkali,  steam  thirty  minutes,  filter  through 
filter  paper,  wash  with  sterile  boiling  hot  water,  tube  at  once,  and  heat  in  the  steamer 
on  three  successive  days  fifteen  minutes,  ten  minutes  and  five  minutes  respectively 
at  ioo°C.  Do  not  autoclave,  and  carefully  avoid  long  heating  in  the  steamer. 
Have  all  glassware  sterile,  the  fluids  sterile  and  sufficiently  boiled  to  begin  with. 
The  very  best  English,  French  or  German  gelatins  should  be  used.  +10  or  +15  is 
a  good  degree  of  alkalinity  for  many  purposes. 

Sugar  Gelatin. 

Water,  c.c 600 

Peptone,  grams 6 

Salt,  grams 3 

Beef  extract,  grams 3 

Glucose,  grams 6 

Gelatin,  grams 60 

The  gelatin  is  added  as  the  mixture  in  water  is  brought  to  a  boil.  The  mixture 
is  cooled  down  to  60°  below  the  coagulating  point  of  albumen  and  the  white  of  two 
eggs  for  every  ioqo  c.c.  of  water  added.  It  is  then  brought  to  a  boil,  the  albumen 
coagulates  and  clarifies  the  medium.  The  fluid  is  then  filtered  through  filter  paper 
previously  wetted  with  boiling  water.  A  funnel  with  wire  support  for  filter  paper  is 
to  be  preferred  for  ease  in  filtering. 


LABORATORY   AND    TEACHING    METHODS 


605 


Sugar  Gelatin  (Another  formula). — Prepare  nutrient  gelatin  and  weigh  out 
glucose  20  grams  (  =  2  per  cent.)  and  dissolve  in  the  hot  gelatin.  Filter,  tube  and 
sterilize  as  for  nutrient  gelatin.  In  certain  cases,  lactose,  maltose  or  saccharose  in 
similar  percentages  is  substituted  for  glucose. 

Litmus  Gelatin. — Prepare  nutrient  gelatin,  add  sterile  litmus  solution,  sufficient 
to  tint  the  medium  a  deep  lavender  color,  tube  and  sterilize  as  for  nutrient  gelatin. 

LESSON  12 

Agar-agar. — To  make  i  liter  of  agar-agar  take 

A.  Dried  peptone  (i  per  cent.),  grams. .  10 
Common  salt  (0.5  per  cent.),  grams. .  5 
Liebig  e.xtract  (0.5  per  cent.),  grams.      5 

Water,   c.c 500 

Boil  for  three  minutes  and  neutralize. 

B.  '  Agar-agar  ( 1 . 2  percent.),  (in  shreds,  or  as 

flour)  grams 12 

Water,   c.c 500 

Chop  the  agar  and  put  into  autoclave  (Fig. 
213).  Run  autoclave  up  to  two  atmospheres  of 
pressure,  giving  i2i.4°C.  of  heat.  As  soon  as 
this  pressure  is  reached,  turn  out  the  flame,  and 
allow  the  autoclave  to  cool  until  below  ioo°C.  be- 
fore opening.  The  two  solutions  A  and  B  are 
then  mixed,  cooled  to  6o°C.,  the  whites  of  two 
eggs  beaten  in  50  c.c.  of  water  added,  well  stirred 
in,  and  the  whole  then  boiled,  the  solidified  albumen 
and  precipitate  skimmed  ofT  and  the  residue  filtered 
through  paper. 

The  whole  process  requires  only  an  hour  and 
a  quarter  to  an  hour  and  a  half,  and  the  result 
is  a  most  excellent  jelly.  Instead  of  .the  white  of 
egg,  blood-serum  may  be  used,  which  seems  to 
add  also  to  the  nutritive  value  of  the  medium. 

Agar  made  with  meat  extract  will  often  form  a  precipitate  during  the  sterilization, 
which  is  objectionable  if  one  wishes  to  use  it  in  the  pouring  of  Petri  dishes,  or  the 
making  of  Esmarch's  roll-tubes. 

Agar  with  Fresh  Meat.— To  make  an  absolutely  and  permanently  clear  agar, 
fresh  meat  should  be  used  as  follows: 

To  make  i  liter'  take: 

A.  Chopped  meat,  grams 500 

Water,  c.c 5^*° 

Mix  and  place  in  cool  place  over  night,  then  strain  through  towel. 

B.  Agar-agar  (1.2  per  cent.),  grams 12 

Water,  c.c 5°° 


Fig.  213. — Usual  form  of 
laboratory  autoclave  for  sterili- 
zation with  steam  under  pres- 
sure. (Fig.  16,  p.  40,  Schneider, 
Pharmaceutical  Bacteriology, 
1912.) 


6o6  LABORATORY   EXERCISES 

Put  in  autoclave,  run  up  to  two  atmospheres  of  pressure,  put  out  flame,  and  allow 
to  cool  until  below  ioo°C.  before  opening  (Fig.  213).  Let  the  solution  of  agar  cool 
still  further  to  about  7S°C.,  and  then  mix  A  and  B,  add  (i  per  cent.)  10  grams  dried 
peptone  and  (0.5  per  cent.)  5  grams  common  salt,  bring  to  a  boil  for  about  three 
minutes,  neutralize  and  filter.  The  product  is  an  absolutely  clear  jelly,  which 
never  forms  any  precipitate.  The  whole  process,  with  the  exception  of  the  time 
the  meat  is  steeping,  requires  only  about  one  hour  and  a  half.  In  both  the  above 
methods  of  making  agar,  the  filtration  is  very  quick — from  ten  to  twelve  minutes 
for  the  liter.  It  is  not  necessary  to  use  a  hot-water  funnel,  but  wet  the  filter  paper 
with  boiling  water  immediately  before  pouring  in  the  agar.  In  the  process  with 
fresh  meat  the  clarification  is  effected  by  the  coagulation  of  the  albumen  in  the 
meat  water,  hence  solution  B  must  not  be  added  to  A  until  cool  enough  to  avoid 
coagulation.  In  general  the  fresh  meat  is  to  be  recommended,  and  the  process  is 
easier  than  with  the  meat  extract,  though  the  latter  has  the  advantage  of  cheap- 
ness and  convenience,  since  the  meat  extract  can  always  be  kept  on  hand,  and  the 
time  lost  in  soaking  the  fresh  meat  is  saved. 

Methods  of  Inoculations  of  Agar-agar. — Agar  is  stored  in  test-tubes  in  one  of  two 
waj's,  viz.:  as  a  straight,  or  cylindric  medium;  or,  as  an  oblique,  or  slanted  medium. 

1.  Oblique  or  slanted  medium.  Here  the  medium  has  been  allowed  to  solidify 
with  the  tube  in  an  inclined  position,  thus  forming  a  flat  surface  extending  nearly 
to  the  mouth  of  the  tube.  Such  slanted  agar  is  used  for  "streak"  (Strich  cultur), 
or  "smear"  cultivations. 

2.  Straight,  or  cylindric,  medium.  Here  the  medium  forms  a  cylindric  mass  in 
the  lower  part  of  the  test-tube  and  the  upper  surface  is  at  right  angles  to  the  long 
axis  of  the  tube.  Such  a  cylindric  medium  is  suitable  for  stab  culture  when  the 
platinum  needle  is  thrust  deeply  into  the  substance  of  the  medium  with  the  needle 
held  vertically. 

LESSON  13 

Various  Nutrient  A  gars. — In  addition  to  beef  bouillon,  or  in  place  of  it,  various 
substances  organic  and  inorganic  may  be  added  to  the  agar  with  advantage. 

Litmus  lactose  agar  is  made  out  of  ordinary  nutrient  agar  by  adding  milk  sugar 
and  enough  pure  litmus  to  give  the  tests.  To  1000  c.c.  of  ordinary  agar,  preferably 
that  made  from  bouillon  free  from  muscle  sugar,  add  10  grams  of  c.p.  lactose  and 
20  c.c.  of  a  saturated  (water)  solution  of  c.p.  (lime-free)  blue  litmus. 

Glycerin  agar,  maltose  agar  may  be  made  with  any  amount  of  the  substance 
desired,  generally  i  or  2  per  cent.  (1000  c.c.  agar  plus  50  c.c.  Schering's  c.p.  glyc-erin). 

Beerivort  agar  is  conveniently  made  in  i  or  2  per  cent,  combinations  of  beerwort 
and  ordinary  agar.  Take  a  measured  quantity  of  agar  by  volume  and  after  it  is 
liquefied  in  the  steam  sterilizer  add  enough  beerwort  by  volume  to  make  a  i  or  2  per 
cent,  quantity  of  that  liquid. 

Glucose  agar  is  a  useful  culture  medium.  Take  i  or  2  per  cent,  of  glucose  by 
weight  (i  gram  =  i  c.c.  by  volume)  and  add  to  a  measured  volume  of  agar  in  the 
liquid  form. 


LABORATORY  AND   TEACHING   METHODS  607 

Dextrose  Agar. 

Dextrose,  grams 10 

Agar,  grams 15 

Water,  c.c 500 

Nutrient  solution  (same  as  for  cellulose  agar)  c.c 500 

Hesse  and  Niedners  Nutrient  Agar  for  Water  Bacteria  (Smith,  p.  196). 

Distilled  water,  c.c 980. 

Nahrstoff  Heyden,  an  albumose,  grams 7.5 

Agar-agar,  grams 12.5 

This  agar  is  said  to  be  the  most  suitable  medium  for  the  bacteriologic  examina- 
tion of  water.  It  gives  a  much  larger  number  of  colonies  than  ordinary  agar.  It 
requires  no  neutralizing.  The  poured  plates  are  counted  according  to  Dr.  Robin 
on  the  ninth  and  tenth  day.  Chromogens  are  brilliantly  colored  (Zeitschr.  fur 
Hygiene,  Bd.  XXIX:  454-462;  see  also  Amer.  Journ.  Pharm.,  LXXVI:  112). 


:4. —  Manner  of  holding  test-tubes  in  making  subcultures.      {After    Williams 
in  Schneider,  Pharmaceutical  Bacteriology,  p.  54.) 


Prune  Agar  (C.  S.  Shear  and  N.  E.  Stevens,  Cultural  Character  of  the  Chest- 
nut Blight  Fungus  and  Its  Near  Relatives.  Circular  No.  131,  U.  S.  Bureau  of 
Plant  Industry). — Take  four  ordinary  prunes  and  add  i  liter  of  water.  Boil  over 
an  open  flame  for  one  hour,  being  careful  not  to  break  the  skin  of  the  prunes.  Strain 
through  gauze,  make  up  to  the  original  amount  with  distilled  water  and  add  2  per 
cent,  of  agar.  Steam  for  three-quarters  of  an  hour,  filter  and  tube.  Autoclave  for 
fifteen  minutes  at  ii5°C.  (Fig.  213). 

Media  for  Mine  Fungi  (Dr.  Caroline  Rumbold). 

1.  Pure  gelatin  10  per  cent.,  20  per  cent.  Bausch  and  Lomb  imported  seal  gelatin. 

2.  6  per  cent,  gelatin,  2.5  per  cent.  Liebig's  extract,  i  per  cent,  citric  acid.  Cox's 
gelatin  can  also  be  used.  This  was  more  successful  than  the  golden  seal  gelatin. 
This  with  i  per  cent,  citric  acid  solidified. 

Laboratory  Work. — Inoculate  any  or  all  of  the  several  nutrient  agars  with  several 
of  the  stock  cultures  of  fungi.  Note  the  rate  of  growth  and  dififerential  character  of 
the  growth  on  the  different  media  (Fig  214). 


6o8 


LABORATORY   EXERCISES 


LESSON    14 

General  Directions  for  Making  Plant  A  gars. — Plant  agars  of  various  kinds  may 
be  made  by  substituting  the  desired  decoction  (made  as  directed  later)  for  the 
bouillon  and  each  looo  c.c.  of  agar  should  contain  the  soluble  nutrients  from  50 
grams  of  dry  weight  of  the  plant  structure  used. 

Decoctions  (F.  D.  Heald)  are  made  by  adding  1000  c.c.  of  cold  distilled  water  to 
50  grams  dry  weight  of  the  substance.  Heat  in  a  steam  sterilizer  and  boil  for 
fifteen  minutes.     The  following  data  are  applicable  in  this  connection. 


Table  of  Dry  Contents 


Potato 

Sugar  beet 
Carrot 

Celery 

Corn  meal. 


Water 
content, 
per  cent. 


Dry 
substance, 
per  cent. 


Approximate  weight 

giving  so  grams  of  dry 

substance,  grams 


25 

200 

18 

27s 

13 

390 

16 

315 

17 

300 

Corn  Meal  Agar. — This  nutrient  medium  is  made  by  taking  300  grams  of  corn 
meal  and  adding  1000  c.c.  of  distilled  water.  Heat  it  in  a  cooker  over  a  gas  burner 
and  boil  for  fifteen  minutes.  The  decoction  is  then  made  up  with  agar  being  used  in 
place  of  bouillon.  Clinton  (Conn.  E.xper.  Sta.  Rep.  1907-08:  898)  gives  these 
directions  for  making  corn  meal  juice  agar.  With  a  50  +  10  +  500  formula;  that  is, 
50  grams  of  dried  corn  meal  (=  300  grams  of  wet  corn  meal),  10  grams  agar-agar 
and  SCO  c.c.  of  water.  The  corn  meal  is  made  into  a  decoction  by  using  not  over 
500  c.c.  of  water  strained  through  fine  cloth,  the  agar-agar  is  added,  heated  long 
enough  to  mi.x  agar-agar  and  filtered. 

Corn  Meal  Agar  {Another  Formula). — To  50  grams  of  corn  meal  add  1  liter  of 
water.  Keep  in  a  water  bath  for  one  hour  at  a  temperature  of  58°C.,  never  over  60°. 
Filter  through  paper,  add  lY^  per  cent,  of  agar  flour,  steam  for  1^2  hours,  filter  and 
tube.  Autoclave  for  fifteen  minutes  at  ii5°C.  Corn  meal  agar  made  by  the  above 
formula  generally  tests  +3. 

Lima  Bean  Juice  Agar  (Clinton:  Conn.  Exper.  Sta.  Rep.  1907-08:  898). — Use 
a  50  +  10  +  500  formula;  that  is,  50  grams  of  dried  ground  lima  beans,  10  grams  of 
agar-agar  and  500  c.c.  of  water.  The  beans  are  ground  as  fine  as  possible  with  a 
fruit  grinder,  and  then  50  grams  are  soaked  one-half  hour  in  tepid  water  (use  as 
much  water  as  necessary,  but  of  course  not  to  exceed  500  c.c.  finally)  and  then 
simmer  slightly  for  another  half  hour.  Strain  off  the  liquid  through  a  fine  wire 
strainer,  add  agar-agar  (better  dissolve  in  a  small  amount  of  water)  and  add  water 
necessary  to  make  500  c.c.  of  medium;  heat  long  enough  to  thoroughly  mix  the  agar- 
agar  and  strain  through  fine  cloth  into  test-tubes. 


LABORATORY   AND   TEACHING   METHODS 


609 


LESSON  15 

Potato  Juice  Agar  (150  +  10  +  500). — Take  150  grams  of  peeled  potato,  slice 
it  thin,  soak  it  in  tepid  water  and  allow  it  to  simmer  for  half  an  hour.  The  juice 
is  used  from  this  in  place  of  bouillon  in  making  the  agar-agar. 

Potato  Agar. — Put  clean  pared  potatoes  rapidly  through  a  grater  and  immedi- 
ately throw  into  the  required  quantity  of  distilled  water,  which  should  be  used  in 
ratio  of  2  c.c.  of  water  to  i  gram  of  the  potato.  Then  put  in  the  Arnold  sterilizer. 
Soak  the  agar  in  water  (i  gram  of  agar  to  100  c.c.  of  water),  add  to  the  potato  and 
mix  thoroughly  (Washington  formula). 


Fig.  215. — Square  form  ut  Arnold  steam  st 
recommended  by  the  Boston  Board  of  Health. 
cetitical  Bacteriology,  191 2.) 


(Fi^ 


■,  showing  two  front  doors  as 
17,  p.  42,  Schneider,  Pharma- 


Mel  T.  Cook's  Formula. — Cook  says  500  grams  in  500  c.c.  of  water,  10  grams  of 
agar  in  500  c.c.  of  water. 

Dr.  Caroline  Rumbold's  Formula. — The  freshly  grated  potato,  500  grams  in  500 
c.c.  of  water,  is  put  in  the  Arnold  steam  sterilizer  and  heated  up  to  90°C.  Part  of 
the  pulp  is  strained  through  cheese  cloth.  7.5  grams  of  agar  are  soaked  in  500  c.c. 
of  distilled  water  and  before  the  agar  has  dissolved,  it  is  put  into  the  potato,  and 
the  whole  thorughly  mixed.  It  is  then  steamed  by  discontinuous  sterilization 
(Fig.  215). 

McBetk  and  Scales  Formula  (McBeth,  I.  G.  and  Scales,  F.  M.:  The  Destruction 

39 


'6 10  LABORATORY   EXERCISES 

of  Cellulose  by  Bacteria  and  Fungi.  Bull.  266,  Bureau  of  Plant  Industry,  1913:  28). 
— Pare,  steam  and  mash  a  quantity  of  potatoes.  To  100  grams  of  mashed  potato 
add  800  c.c.  of  tap  water  ar.d  steam  for  one-half  hour;  filter  through  cotton. 

Potato  solution,  c.c 500 

Agar,  grrims 15 

Nutrient  solu  tion,  c.c 500 

Potato  Agar  (AnCither  formula). — Put  clean  pared  potatoes  through  a  meat 
gB-inder.  To  1000  gn  ims'of  the  potato  pulp  add  an  equal  quantity  of  distilled  water. 
Stir  thoroughly  aJid  let  stand  in  an  ice  box  for  an  hour,  with  occasional  stirring. 
Strain  through  gauz€  of  medium  mesh.  Make  up  to  three  times  the  weight  of  the 
original  pulp  with  di  stilled  water.  Strain  for  one  hour,  filter  through  cotton  and 
paper  and  make  up  to  3000  c.c.  with  distilled  water.  Add  i^i,  per  cent,  of  agar 
flour,  steam  for  one  hour,  filter  through  cotton  and  paper,  tube  and  autoclave  for 
fifteen  minutes  at  1 1  s^C.  As  this  potato  agar  varies  widely  in  acidity,  to  reduce  this 
variation  a  large  cjuan  tity  of  potato  juice  made  from  a  uniform  lot  of  Burbank  po- 
tatoes is  used.  This  if ,  placed  in  looo-c.c.  flasks  tightly  plugged  and  kept  in  a  refrig- 
erator. The  juice  is  "then  made  up  in  agar  tubes  as  needed.  It  was  found  that  this 
agar  varied  less  than  i  per  cent,  in  acidity,  changing  from  -[-7  to  -|-6  during  five 
months. 


LESSON  16 

Starch  Agar—  -TfefSjoo  c.c.  of  boiling  water  add  10  grams  of  potato  starch  sus- 
pended in  a  little  eoitfi  water..  Concentrate  by  boiling  to  500  c.c.  This  breaks  up 
the  starch  grains    endJ  it  should  give  a  nearly  transparent  starch  solution. 

Starch  solu  ifiiiam,  c.c Soo 

Nutrient  S(  Jtetion  (same  as  for  cellulose  agar),  c.c 500 

Agar,  gran  is... 10 

Cellulose  Agar  (Ai  "^cBeth  and  Scales:  Bull.  266,  Bureau  of  Plant  Industry, 
p.  27). — Prepare  a^  Mt<  ^r  of  dilute  ammonium  hydroxide  solution  by  adding  3  parts 
of  water  to  10  parts  o;  f  ammonium  hydroxide,  sp.  gr.  0.90.  Add  a  slight  excess  of 
copper  carbonate  ands.  hake,  allow  to  stand  over  night  and  then  siphon  off  the  super- 
natant solution.  AcM  10  grams  of  unwashed  sheet  filter  paper  and  shake  occasion- 
ally until  the  paper  isi;  'ssolved.  Dilute  to  10  liters  and  add  slowly  a  i  to  5  solution 
of  HCl,  with  vigorous  ,  shaking  until  the  precipitation  of  the  cellulose  is  complete. 
Dilute  to  20  liters,  fjilib?  w  the  cellulose  to  settle  and  decant  the  supernatant  liquid. 
Wash  by  repeated  clha  iges  of  water,  adding  HCl  each  time  until  the  copper  color 
disappears;  then  wa^  with  water  alone  until  the  solution  is  free  from  chlorine. 
Allow  it  to  settle  severnil  days  and  decant  off  as  much  of  the  clear  solution  as  possible. 
If  the  percentage  of:  fflt  llulose  is  still  too  low,  a  portion  of  the  solution  is  centri- 
fugalized  to  bring  i-^  ifc  ellulose  content  up  to  i  per  cent. 


LABORATORY  AND   TEACHING   METHODS  Oil 

Cellulose  solution,  c.c 500 

Agar,  grams 10 

Nutrient  solution,  as  follows: 

Potassium  phosphate  (dibasic),  gram i 

Magnesium  sulphate,  gram i 

Sodium  chloride,  gram i 

Ammonium  sulphate,  grams 2 

Calcium  carbonate,  grams 2 

Tap  water,  c.c 1000 

Chestnut  Twig  Agar. — To  275  grams  of  one-  or  two-year-old  chestnut  branches 
add  500  c.c.  of  distilled  water  and  boil  over  an  open  flame  for  one-half  hour.  Filter 
the  juice  and  make  up  to  550  c.c.  with  distilled  water.  To  50  parts  of  this  infusion 
add  100  parts  of  distilled  water  and  2  per  cent,  of  agar  flour.  Steam  for  one-half 
hour,  filter,  tube  and  autoclave  for  fifteen  minutes  at  ii5°C. 

LESSON  17 

Culture  Medium. — Winogradsky  employed  for  culturing  upon  solid  media  a 
mineral  gelatin.  A  solution  of  from  3  to  4  per  cent,  of  silicic  acid  in  distilled  water 
is  placed  in  flasks.  By  addition  of  the  following  salts  to  such  a  solution  gelatiniza- 
tion  occurs. 

(a)        Ammonium  sulphate,  gram 04 

Magnesium  sulphate,  gram 0.05 

Calcic  chloride a   trace 

{b)        Potassium  phosphate,  gram o.  i 

Sodium  carbonate,  gram 0.6,0.9 

Distilled  water,  c.c 100 .  o 

The  sulphates  and  chloride  are  mixed  in  50  c.c.  of  distilled  water,  and  the  latter 
substance  in  the  remaining  50  c.c.  in  separate  flasks.  After  sterilizing  and  cooling 
these  are  all  mixed  and  added  in  small  quantities  to  the  silicic  acid.  Upon  this 
medium,  it  is  possible  to  subculture  a  pure  growth  from  the  film  at  the  bottom  of 
the  flasks  in  which  the  nitrous  organism  is  first  isolated  (c/.  Newman,  George: 
Bacteria,  pp.  154-157). 

Isolation  of  the  Nitric  Organisms. — Nitrobacter  develops  freely  in  solutions  to 
which  no  organic  matter  has  been  added;  indeed,  much  organic  matter  will  prevent 
its  growth.     Winogradsky  used  the  following  medium  to  isolate  it: 

Water,  c.c 1000  o 

Potassium  phosphate,  gram i .  o 

Magnesium  sulphate,  gram 0.5 

Calcium  chloride a   trace 

Sodium  chloride,  grams 2.0 

About  20  c.c.  of  this  solution  is  placed  in  a  flat-bottom  flask  and  a  little  freshly 
washed  magnesium  carbonate  is  added.    The  flask  is  closed  with  cotton-wool,  and 


6l2 


LABORATORY   EXERCISES 


the  whole  is  sterilized.  To  each  flask  2  c.c.  of  a  2  per  cent,  solution  of  ammonium 
sulphate  is  subsequently  added.  The  temperature  for  incubation  is  3o°C  (Fig. 
216),  This  organism  can  be  successfully  grown  on  silicate  jelly.  As  silicate  jelly 
is  difficult  to  make  it  is  optional  for  the  students  to  attempt  its  manufacture.  For 
reference  the  method  is  given. ^ 

Pot  Experiments  with  Nitrogen  Fixation.-— ?>\nct  the  experiments  of  Hellriegel 
and   Wilfarth   and  other  experimenters,  it  has  been  known  that  certain  bacteria 


Fig.  216. — Double-walled  copper  incubator  constructed  with  non-conducting 
materials,  with  water  gauge  and  openings  for  insertion  of  thermometer  and  thermo- 
stat. Padded  outer  door  of  copper,  inner  door  of  glass.  (Fig.  22,  p.  46,  Schneider', 
Pharmaceutical  Bacteriology,  191 2.) 


{Bacillus  radicicola,  etc.)  have  the  power  of  fixing  free  atmospheric  nitrogen,  when 
they  enter  the  roots  of  leguminous  plants  with  the  formation  of  root  nodules.  The 
formation  of  these  nodules  can  be  followed  in  a  series  of  experiments. 

^  It  is  optional  of  course  for  the  teacher  to  omit  these  rather  difficult  exercises 
entirely.  If  followed  by  the  student  or  class,  a  useful  work  to  consult  in  connection 
with  Lesson  17  is  Smith,  Erwin  F.:  Bacteria  in  Relation  to  Plant  Diseases,  I  :  36-39. 

2  An  important  paper  on  the  culture  and  isolation  of  Bacillus  radicicola  is  by 
Harrison,  F.  C.  and  Barlow,  B.:  The  Nodule  Organism  of  the  Leguminosae— Its 
Isolation,  Cultivation  and  Commercial  Application.  Centralblatt  fiir  Bakteriologie, 
Parasitenkunde  und  Infektionskrankheiten,  19,  Abt.  2,  1907:  264-272,  426-440, 
pis.  9.  Consult  for  other  details  Lipman,  J.  G.  and  Brown,  P.  E.:  A  Laboratory 
Guide  in  Soil  Bacteriology,  191 1. 


LABORATORY   AND   TEACHING   METHOr)S  613 

Take  three  pots  A,  B,  C,  which  have  been  thoroughly  sterilized  by  dry  heat  in 
a  sterilizing  oven.  Place  in  pot  A  ordinary  rich  garden  soil.  Fill  pot  B  and  C  with 
sand  and  thoroughly  sterilize  both  pot  and  sand  with  dry  heat.  Plant  in  pots,  A,  B 
and  C  seeds  of  pea,  bean,  clover  or  those  of  other  leguminous  plants  and  water 
pots  A,  and  B  only  with  distilled  water  previously  carefully  sterilized.  Pot  C  with 
sand,  is  watered  with  distilled  water  which  has  been  allowed  to  percolate  through 
rich  garden  earth  and  which  removes  the  bacterial  life  which  such  rich  soil  con- 
tains. Pot  C  watered  with  such  water,  therefore,  becomes  microbe-seeded.  After 
the  first  watering,  all  subsequent  applications  of  water  should  be  made  with 
thoroughly  sterilized  distilled  water. 

Note  daily  the  growth  of  the  plants  in  each  of  the  pots  and  explain  the  difference 
in  the  rate  and  character  of  the  growth,  if  any. 

In  order  to  be  able  to  study  microscopically  the  entrance  of  the  organisms  from 
the  soil  into  the  root  of  the  leguminous  plants  a  larger  series  of  pots  should  be  used 
than  three.  By  doing  this  successive  stages  in  the  development  of  the  nodules  can 
be  obtained  and  made  ready  for  microscopic  study  by  the  paraffin  method  described 
in  a  subsequent  lesson  (Page  656). 

LESSON  18 

Standardization  of  Culture  Media  (F.  D.  Heald). — Bacteria  and  fungi  are  in- 
fluenced in  their  development  by  the  degree  of  acidity  or  alkalinity  of  the  medium 
in  which  they  are  growing.  Since  this  is  true,  it  is  important  to  employ  media  of 
known  reaction.  In  order  to  secure  results  which  may  be  compared,  the  adoption 
of  a  uniform  method  of  standardization  is  necessary  and  the  reaction  of  a  culture 
medium  should  be  indicated  always  when  cultural  or  morphologic  characters  are 
described.     The  standardization  of  culture  media  requires  the  following  solutions: 

N 
c^r— r—  =  a  normal  solution  of  sodium  hydroxide. 

'N 

—  NaOH  =  twentieth  normal  solution  of  sodium  hydroxide. 

N 
ff™  =  normal  hydrochloric  acid. 

.  N  N 

The  —  NaOH  is  used  for  the  titration  of  culture  media  and  the  ^^-7^^  for  their 
20  NaOH 

N 
neutralization,     vj^  is  used  for  acidifying  media.     A  normal  solution  contains 

I  gram  of  basic  H,  or  the  equivalent  to  each  1000  c.c.  Since  the  above  normal  solu- 
tions are  required  in  every  pathologic  laboratory,  directions  are  here  given  for  their 
preparation. 

Preparation  of  Normal  Solutions. — Normal  solutions  of  NaOH  or  HCl  cannot  be 
made  by  weighing.  NaOH  readily  absorbs  CO2  and  water  from  the  air  and  so  can- 
not be  weighed  accurately  enough  for  making  standard  solutions.  HCl  is  liquid 
and  of  varying  strength.  It  is  necessary,  then,  to  start  with  an  acid  or  alkali  that 
is  in  solid  crystalline  form  and  is  not  altered  on  exposure  to  the  air.  Oxalic  acid 
presents  the  requisite  characteristics. 


6 14  LABORATORY   EXERCISES 

N  .        .  .  . 

—  Oxalic  Acid  Solution. — Weigh  out  exactly  6.3  grams  of  chemically  pure  oxalic 

acid  (H2C2O4  plus  2H2O)  and  add  distilled  water  in  looo-c.c.  volumetric  flask. 
After  the  crystals  of  acid  have  dissolved,  dilute  the  solution  until  it  measures  exactly 
1000  c.c. 

N 
Tj— 7;tf  or  Normal  Sodium  Hydroxide. — This  solution  should  contain  40  grams  of 

NaOH  in  i  liter.  It  can  be  made  by  titrating  against  the  standard  oxalic  solution 
already  prepared.  Weigh  out  90  grams  of  NaOH  and  dissolve  in  2  liters  of  dis- 
tilled water.     This  solution  is  now  too  strong  and  the  amount  necessary  to  dilute  it 

N 
must  be  determined.     Place  exactly  50  c.c.  of  the       oxalic  acid  in  a  beaker  and  add 

10 

a  few  drops  of  phenolphthalein  solution  to  serve  as  an  indicator  and  then  add  to  this 
drop  by  drop  from  a  burette  some  of  the  NaOH  solution,  stirring  with  a  glass  rod 
and  continue  until  the  solution  is  turned  a  faint,  but  permanent  pink  color.     Read  off 

N 
from  the  burette  the  amount  of  NaOH  solution  used  to  neutralize  50  c.c.  ot  — 

10 

oxalic  acid,  which  contained  as  much  acid  as  5  c.c.  of  normal  acid.  Now  calculate  the 
amount  of  dilution  necessary.  Supposing  4.5  c.c.  of  NaOH  be  the  amount  used  and 
1950  c.c.  the  amount  of  NaOH  to  be  diluted,  the  proportion  would  be  as  follows: 
4.5  :  5  ::  1950  :  x  where  x  =  2167,  and  this  means  that  2167  c.c.  of  water  must  be 
used.  After  the  dilution,  repeat  the  titration  and  adjust  if  necessary. 
N 
TTpj  or  Normal  Hydrochloric  Acid. — This  may  be  prepared  by  making  an  acid 

solution  which  is  a  little  over  strength,  and  determining  the  amount  of  dilution 

N  N 

necessary  by  titrating  with  the  „  ^^-      i  c.c.  of  c^t^  should  exactly  neutralize 

N  ^  .        ^ 

ic.c.ofjj^l- 

Expressing  the  Reaction  of  Media. — Fuller's  scale  has  been  generally  adopted  for 
expressing  the  reaction  of  culture  media.  The  plus  sign  (+)  indicates  that  the 
medium  is  acid  to  phenolphthalein,  while  the  minus  sign  (  — )  indicates  that  the  me- 
dium is  alkaline  to  phenolphthalein,  the  figure  following  the  sign  indicating  the 

N 
degree  of  acidity,  or  alkalinity.     For  example,  a  -f  10  medium  contains  10  c.c.  of  tt;^, 

for  1000  c.c.  beyond  the  neutral  point  for  phenolphthalein  paper.     A  —  10  medium 

N 
is  alkaline  and  would  require  10  c.c.  of  t77^\  for  1000  c.c.  to  bring  it  back  to  the 

neutral  point.  Media  may  then  have  the  reaction  +  5,  +  10,  +  15,  etc.,  or  —  5, 
—  10,  —15,  etc.  The  neutral  point  for  litmus  is  not  the  same  as  the  neutral  point 
for  phenolphthalein  and  this  fact  should  be  kept  in  mind  when  working  with  culture 
media. 

25  of  Fuller's  scale  gives  approximately  the  neutral  point  for  litmus,  so  that  any 
medium  with  a  reaction  less  than  +  25  is  still  alkaline  to  litmus. 

The  Optimum  Reaction. — For  every  organism  there  is  a  definite  optimum  reaction. 
It  lies  near  -f  5  for  most  animal  pathogens,  about  -fio  to  +15  for  most  water  and 


LABORATORY   AND   TEACHING   METHODS  615 

putrefactive  bacteria  and  +10  to  +25  or  even  higher  for  fungi.  There  are  some 
bacterial  organisms  which  prefer  distrnctly  alkaline  media  (Fuller's  scale),  while 
others  prefer  acid  media.  A  good  general  practice  to  follow  in  the  preparation  of  the 
basic  culture  media  to  be  kept  in  stock  iis  to  standardize  to  +10  of  Fuller's  scale  and 
vary  the  reaction  according  to  the  preierence  of  the  organisms  under  cultivation. 
When  other  acids  than  HCl  are  used  for  acidifying  the  media,  the  kind  should  be: 
definitely  specified,  when  the  reaction  is  expressed. 

Titration  of  Media. — In  outlining  the  m  ethod  of  preparation  of  bouillon  for  routine 
work,  directions  were  given  for  neutralization  of  the  medium  and  the  addition  of  the 
requisite  amount  of  acid.  In  accurate  work,  or  in  the  prosecution  of  research,  a 
more  careful  method  of  standardizati.on  is  employed.  The  medium  should  be 
neutralized  by  the  titration  method.     iTie  process  is  as  follows: 

1.  Add  exactly  5  c.c.  of  the  medium  to  45  c.c.  of  distilled  water  in  an  evaporating 
dish  (use  a  5-c.c.  Mohr  pipette),  boil  for  three  minutes  to  drive  off  the  CO2  and  add 
I  c.c.  of  phenolphthal(;in  solution. 

N 

2.  Add  —  NaOH  drop  by  drop  from  a  burette,   stirring  constantly  until   the 

20 

solution  turns  a  faint,  but  permanent  pink.     Repeat  the  titration  for  two  more  5-c.c. 
samples,  and  determine  the  average  of  the  three  readings. 
N 

3.  Calculate  the  amount  oi  ^  ^.tV  necessary  to  neutralize  the  medium  (10  to 

15  CO.),  add  the  amount  determined  to  the  medium,  te^t  reaction  and  if  neutral,, 
proceed  with  preparation  of  the  medium;  if  not,  repeat  the  titration  on  neutralization. 

LESSON  19 

Germination  Studies. — The  examination  of  spore  germination  of  various  fungi  can 
be  studied  best  by  the  hanging-drop  method.  Take  a  hanging-drop  slide  and  sterilize 
thoroughly  in  the  hot-a  ir  oven  at  iio°C.  after  it  has  been  wrapped  in  a  crepe  napkin 
or  piece  of  tissue  paper.  After  sterilization  plunge  it  into  a  beaker  of  absolute  alcohol 
(or  such  sterilized  slides  may  be  kept  in  stock  in  absolute  alcohol)  and  then  drain 
off  the  greater  part  of  the  spirit,  grasping  the  slide  in  a  pair  of  sterile  forceps.  Burn 
off  the  remainder  of  the  alcohol  in  the  flames. 

Place  the  hanging-drop  slide  on  a  piece  of  blotting  paper  moistened  with  a  2 
per  cent,  lysol  solution  and  cover  it  with  a  small  bell  glass  that  has  been  rinsed  with 
the  same  solution  and  not  dried. 

Raise  the  bell  glass  slightly  and  smear  sterile  vaseline  around  the  rim  of  the  cell 
by  means  of  a  steriHe  spatula  of  stout  platinum  wire.  Remove  a  clean  cover-slip 
from  the  alcohol  pot  with  sterile  forceps  and  burn  off  the  alcohol;  again  raise  the 
bell  glass  and  place  the  sterile  cover-slip  on  the  blotting  paper  by  the  side  of  the 
hanging-drop  slide. 

Remove  a  drop  of  the  culture  medium  selected  for  use  (see  below)  and  place  the 
drop  on  the  center  of  ihe  cover-slip.     Sterilize  the  loop. 

Raise  the  bell  glass;  sufficiently  to  allow  of  the  cover-slip  being  grasped  with  the 
sterile  forceps,  invert  it  and  place  over  the  cell  of  the  hanging-drop  slide.  Remove 
the  bell  glass  altogether  and  press  the  cover-slip  firmly  on  the  cell. 


6l6  LABORATORY   EXERCISES 

Germination  on  Solid  Media. — Observing  precisely  similar  technique  a  few  drops 
of  liquefied  gelatine  or  agar  may  be  run  over  the  surface  of  the  cover-slip  and  a 
hanging-drop  plate  cultivation  thereby  prepared.  After  sealing  down  the  prepara- 
tion it  may  be  set  aside  and  the  growth  watched  at  definite  intervals  under  the 
microscope. 

Dilution  Method  to  Obtain  Material  for  Inoculating  Hanging-drop  Media. — In 
the  case  of  yeast  this  problem  was  solved  by  Hansen,  who  developed  the  method  to 
such  a  degree  of  perfection  as  to  create,  in  fact,  an  exact  method  (1881).  He 
employed  dilution  with  water.  The  yeast  developed  in  the  flask  is  diluted  with  an 
arbitrary  amount  of  sterilized  water,  and  after  vigorous  shaking,  the  number  of 
cells  in  a  small  drop  of  liquid  is  determined.  The  counting,  in  this  case,  is  effected 
in  a  very  simple  manner  by  transferring  a  drop  to  a  cover-glass,  in  the  center  of  which 
some  small  squares  are  engraved  and  this  is  then  connected  with  a  moist  chamber; 
the  drop  must  not  be  allowed  to  extend  beyond  the  limits  of  the  square.  The  cells 
present  in  the  drop  are  then  counted.  Suppose,  for  instance,  that  ten  cells  are 
found:  a  drop  of  similar  size  is  transferred  from  the  liquid,  which  must  first  be 
shaken  vigorously,  to  a  flask  containing  a  known  volume  of  water,  e.g.  20  c.c.  of 
sterilized  water.  This  flask,  then,  will  in  all  likelihood  contain  about  ten  cells.  If 
it  is  then  vigorously  shaken  for  some  time  until  the  cells  are  equally  distributed  in 
the  water,  and  then  i  c.c.  of  the  liquid  introduced  into  each  of  twenty  flasks  contain- 
ing nutritive  liquid,  it  is  probable  that  half  of  these  twenty  flasks  have  received  one 
cell  each.  But,  here  again,  as  in  Lister's  experiments,  it  is  entirely  a  calculation 
of  probabilities.  If  the  flasks  are  allowed  to  stand  for  further  development  of  micro- 
organisms, there  will  be  a  chance  of  getting  a  pure  culture  in  some  of  them.  Hansen 
succeeded,  however,  in  adding  a  new  factor,  which  first  gave  certainty  to  this  experi- 
ment. Thus,  if  the  freshly  inoculated  flasks  are  vigorously  shaken,  and  then  left  in 
repose,  the  individual  cells  will  sink  to  the  bottom  and  be  deposited  on  the  walls  of 
the  flask.  It  is  self-evident  that  if  a  flask  contains,  for  instance,  three  cells,  these 
cells  will  always,  or  at  least  in  the  great  majority  of  cases,  be  deposited  in  three 
distinct  places  on  the  bottom.  After  some  days,  if  the  flask  is  raised  carefully,  it 
will  be  observed  that  one  or  more  white  specks  have  formed  on  the  bottom  of  the 
flask.  If  only  one  such  speck  be  found,  we  have  a  pure  culture  by  the  dilution 
method. 

Method  of  Preparing  Squared  Cover-glasses.- — Since  such  cover-glasses  are  some- 
what expensive  and  can  be  easily  etched,  the  method  of  their  preparation  is  de- 
scribed below.  A  little  paraffin  or  wax  is  melted  in  a  saucer  and  the  cover-glass 
dipped  into  it,  being  held  at  one  corner  by  a  forceps;  it  is  taken  out  quickly  and  as 
much  as  possible  of  the  melted  parafiin  is  allowed  to  run  off,  leaving  on  either  side  a 
thin  cover  of  parafiin  which  is  allowed  to  harden.  By  a  very  fine  needle  and  a  small 
ruler  the  required  lines  are  then  scratched  on  the  wax,  and  the  cover-glass  immersed 
for  a  moment  in  hydrofluoric  acid  which  should  be  poured  into  a  platinum  crucible 
or  dish.  The  paraffin  can  now  be  dissolved  off  in  xylol,  leaving  the  surface  etched 
with  the  squares  used  in  making  bacterial,  or  fungous  spore  counts  (Fig.  217). 

These  squared  covers  may  be  raised  above  the  slide,  while  the  count  is  being  made, 
either  on  four  pillars  of  paraffin,  or  in  a  moist  chamber. 


LABORATORY  AND  TEACHING  METHODS 


617 


LESSON  20 

Counting  of  Yeast  Cells,  Fungous  Spores  and  Bacteria. — In  many  cases  the  cells 
are  in  a  liquid  which  is  inclined  to  form  froth  when  shaken,  hence  the  liquid  can  be 
treated  with  dilute  sulphuric  acid  (i  part  concentrated  sulphuric  acid  and  10  parts 
water).  This  prevents  aggregations  of  the  cells  and  also  furnishes  in  addition  a 
liquid  in  which  cells  do  not  sink  to  the  bottom  too  quickly,  an  important  point,  when 
single  drops  are  taken  out  for  counting  purposes. 

In  counting,  the  counting  chamber  is  employed.  Thoma's  ha;matimeter  consists 
of  a  glass  slip  on  which  a  cover-glass  is  fastened  which  has  a  circular  hole  "in  the 


2 

3 

4 

5 

6 

7 

8 

9 

10 

12 

13 

14 

15 

16 

17 

18 

Fig.  217. — A,  Squared  cover  glass  used  in  counting;  B,  Jorgensen's  squared 
cover  glass;  C,  moist  chamber,  sectional  view;  D,  moist  chamber  with  Jorgensen's 
squared  cover.      {A  and  B,  after  Klocker;  C,  original;  D,  after  Jorgensen.) 


middle  and  is  0.2  mm.  thick  (Fig.  218).  A  circular  cover-glass,  o.i  mm.  thick,  is 
fitted  centrally  in  this  hole  and  is  also  fastened  to  the  glass  slip;  thus  an  annular 
space  is  formed.  In  the  middle  of  the  cover-slip  two  sets  of  twenty-one  parallel 
lines  are  etched  which  cut  each  other  at  right  angles;  there  are  thus  formed  a  large 
square  with  a  side  of  i  mm.  and  small  squares  with  a  side  of  0.05  mm.  The  drop  of 
liquid  taken  up  by  a  pipette  is  examined  on  this  square  and  enclosed  by  the  cover- 
glass,  the  depth  of  the  liquid  layer  thus  formed  amounting  to  o.i  mm.  (Fig.  218). 

Thoma's  H cematimeter . — After  the  test-tube  with  the  average  sample  and  the 
H2SO4  has  been  subjected  to  a  prolonged  and  vigorous  shaking,  a  sample  is  taken  out 
and  examined  as  above. 


6i8 


LABORATORY    EXERCISES 


As  soon  as  the  cover-glass  has  been  put  into  position  the  chamber  is  laid  under 
the  microscope,  and  if  a  haematimeter  is  being  used  as  a  counting  chamber  the  "net 
eyepiece"  is  required.  It  is  not  advisable  to  use  a  greater  magnification  than  is 
necessary.  After  waiting  a  short  time,  the  counting  is  proceeded  with  when  all  the 
cells  in  the  preparation  have  sunk  to  the  bottom.  The  "net  eyepiece"  consists  of 
a  large  square  divided  into  sixteen  or  twenty-five  smaller  squares,  the  latter  being 
used  as  aids  in  counting.  The  cells  inside  the  large  square  are  counted;  it  does 
not  matter  how  the  cells  lying  on  the  side  lines  of  the  square  are  counted,  if  the 
same  rule  is  always  followed.  Many  squares  in  each  haematimeter  may  be  counted 
by  di^placihg  the  haematimeter.     It  is  to  be  recommended  always  to  count  a  certain 


Tief-e 

0.1  OO    mmi 

1       A      1 
400  ^    25 
q  mm. 

d 

^ermdny 

A 

#' 

d  e  c    b 


[8. — Details  of  Thoma's  haematimeter.     A,  Surface  view  of  thick  glass  slide 
with  chamber  and  ruled  center;  B,  cover  glass;  C,  sectional  view. 


number  of  squares,  e.g.  ten — two  in  the  middle  and  eight  along  the  edge  of  the  drop. 
As  soon  as  these  ten  countings  are  performed,  the  haematimeter  is  well  cleaned  and 
dried,  the  second  test-tube  well  shaken  and  then  a  drop  taken  from  it  and  counted  in 
the  same  manner.     This  alternation  is  repeated  until  a  constant  average  is  obtained. 

When  it  is  not  necessar)'  to  determine  the  number  of  cells  in  a  given  volume, 
the  same  unit  of  volume  is  always  employed,  viz.,  that  of  a  column  of  liquid  of  which 
the  base  is  the  large  square  of  the  "net  eyepiece"  for  the  particular  magnification 
employed,  the  height  being  the  thickness  of  the  perforated  cover-glass. 

For  example,  3  cc.  of  beerwort  with  yeast  cells  and  i  c.c.  of  sulphuric  acid  give 
the  following  results. 


LABORATORY   AND   TEACHING   METHODS 


619 


Sample  i 


Square 

First  drop 

Second  drop 

Third  drop 

Fourth  drop 

I 

23 

10 

28 

13 

2 

22 

20 

20 

24 

3 

19 

28 

19 

21 

4 

10 

19 

22 

14 

5 

14 

24 

32 

18 

6 

27       • 

26 

25 

20 

7 

20 

14 

21 

19 

8 

18 

25 

13 

34 

9 

12 

20 

17 

23 

10 

27 

14 

20 

16 

Average 

19.2 

20.0 

21.7 

20.2 

Cells  in  each  large  square 


Calailatioti  of  Counts. — As  these  four  averages  are  nearly  the  same,  it  is  not 

necessary  to  count  more  drops.     The  mean  of  the  four  averages  is      '    =  20.275 

4 
cells  per  unit  of  volume.     But  since  the  wort  was  diluted  with  H2SO4  (4  parts  of 
the  mixture  contains  3  parts  of  wort  with  cells)  the  actual  number  of  cells  in  the 

,          .            ,.       .    20.275X4  „ 

volume  m  question  is =  27  cells. 

Detailed  Description  of  Thoma's  Hamatimeter  (Figs.  218  and  218A). — ^Thoma's 
haematimeter  (Zeiss  form)  is  used  also  for  counting  microorganisms.  .4  is  a  glass 
slide  on  which  a  cover-glass  (a)  is  fastened  which  has  a  circular  hole  in  the  middle 
and  is  0.2  mm.  thick.  A  circular  cover-glass  (c),  o.i  mm.  thick  is  fitted  centrally 
in  this  hole  and  is  also  fastened  to  the  glass  slide;  thus  an  annular  space  {d)  is  formed. 
In  the  middle  of  (c)  two  sets  of  parallel  lines  are  etched  which  cut  each  other  at 
right  angles.  There  are  thus  formed  a  large  square  with  a  side  of  i  mm.,  and  small 
square  with  a  side  of  0.005  mm.  The  drop  of  liquid  to  be  examined  is  placed  on 
this  square  and  enclosed  by  the  cover-glass  (6),  the  depth  of  the  liquid  layer  (e) 
thus  formed  amounting  to  o.oi  mm.     B  gives  a  vertical  section  of  the  chamber. 

If  the  actual  number  of  cells  in  a  certain  volume  is  to  be  calculated,  the  size  of 
the  space  unit  must  be  determined.  It  is  then  necessary  to  know  the  height  of  the 
column  of  Hquid,  i.e.,  the  thickness  of  the  perforated  cover-glass.  The  haematimeter 
designed  by  Hayem  and  Nachet  has  one  with  a  thickness  of  0.2  mm.,  but  that  in  the 
Zeiss  hasmatimeter  is  usually  o.i  mm.  The  value  of  the  square  in  the  "net"  for 
the  magnification  used  must  further  be  known,  or  squared  cover-glasses  are  used  of 
which  the  size  of  the  squares  is  known.  In  Thoma's  chamber  the  column  of  liquid 
is  0.1  mm.  high  and  the  large  square  etched  on  the  bottom  of  the  chamber  contains 
I  sq.  mm.  The  volume  of  the  liquid  prism,  of  which  the  base  is  the  large  square,  is 
thus  0.1  cu.  mm. 


620 


LABORATORY   EXERCISES 


When  It  is  intended  to  sow  a  definite  number  of  cells,i  water  is  usually  added  to 
the  yeast  to  be  used  as  sowing  material,  the  cells  being  thus  more  easily  separated 
from  one  another  on  shaking;  also,  no  appreciable  increase  of  the  cells  takes  place, 
especially  if  the  flask  is  subjected  to  a  low  temperature  after  the  sample  has  been 
withdrawn. 


Fig.  2i8A. — Blood  counter  case,  a,  Slide  with  counting  chamber;  b,  rubber  cork 
covering  tip  of  white  pipette;  c,  soft  rubber  tubing;  d,  red  pipette  provided  with 
rubber  cork;  e,  cutting  needle  in  95  percent,  alcohol;  g,  Hayem's' solution;  h,  .5  per 
cent,  acetic  acid.      {After  McJunkin.) 


The  yeast  is,  therefore,  shaken  up  vigorously  and  continuously  with  sterile  water, 
and  an  average  sample  removed.  There  are  three  different  cases  to  be  considered 
now  viz.:  (i)  When  we  wish  to  know  only  how  many  cells  are  present  in  a  certain 
portion  of  the  water-yeast  mixture;  (2)  when  it  is  intended  to  inoculate  a  previously 
determined  number  of  cells  into  the  liquid  to  be  dealt  with;  and  (3)  when  it  is  desired 
to  sow  so  many  cells,  that  after  the  seeding  the  definite  number  of  cells  desired  may 
be  present  in  an  arbitrary  space  unit,  e.g.,  when  making  comparisons  of  the  multiply- 

1  Klocker,  Alb.:  Fermentation  Organisms,  1903. 


LABORATORY   AND   TEACHING  METHODS  62 I 

ing  powers  of  two  species.  In  the  first  two  cases,  it  is  required  to  determine  the 
actual  number  of  cells  which  are  to  be  seeded,  and  no  attention  is  paid  to  the  quantity 
of  liquid  indtulated;  in  the  last  case,  it  is  required  only  to  know  the  relative  number 
of  cells,  but  regard  must  be  had  to  the  quantity  of  liquid  seeded.  Finally,  the  follow- 
ing must  be  remembered:  If  there  is  to  be  a  definite  volume  in  the  flask  after  seed- 
ing, then,  in  the  case  where  the  seeding  is  not  to  be  made  in  water,  or  where  the  con- 
centration of  the  liquid  is  of  some  account,  no  water  must  be  used  in  shaking  up  the 
yeast.  In  this  case  the  same  culture  liquid  must  be  employed.  The  same  quantity 
of  culture  liquid  is  then  removed  from  the  flask  before  seeding,  as  will  be  added  when 
seeding  takes  place. 

The  procedure  in  the  above  three  cases  is  as  follows:  (i)  After  shaking,  a  drop  of 
the  water  is  placed  in  the  haematimeter,  or  in  the  Thoma  chamber,  and  the  number 
of  cells  is  determined  in  the  usual  manner.  On  seeding  a  measured  portion  of  the 
water  mixture  is  taken,  and  we  thus  know  how  many  cells  have  been  sown. 

2.  As  above.  In  counting  we  learn,  for  example,  that  a  cells  are  present  in  a 
certain  volume.  It  is  here  necessary  to  know  the  quantity  of  culture  liquid  in  the 
flask  to  be  inoculated;  assume  the  amount  to  be  p  c.c.  If  it  is  desired  to  sefed  so 
many  cells  that  there  will  be  ai  cells  per  unit  of  volume,  the  number  of  cubic  centi- 
meters X  of  the  water-yeast  mixture,  which  must  be  added  in  order  to  arrive  at  this, 

a        p  -\-  X 
is  found  from  the  following  equation:  —  =  ; —  or  the  number  of  cells  in  the 

water  mixture  (the  seeding  liquid)  has  the  same  proportion  to  the  cells  after  seed- 
ing as  the  whole  amount  of  liquid  after  seeding  has  to  the  amount  of  seeding  liquid. 
The  quantity  of  liquid  in  the  flask  after  seeding  has  taken  place  is  thus  p  -\-  x. 

From  the  given  equation,  x  = .     Example:  It  is  found  that  the  seeding 

a  —  02 

liquid  contains  75  cells  per  unit  of  volume  and  the  flask  to  be  infected  contains  70 
c.c.  of  wort,  and  it  is  further  desired  to  have  5  cells  per  unit  of  volume  after  inocula- 
tion.    Accordingly,  x  =  =  5  c.c.  to  be  withdrawn  from  the  seeding  liquid. 

75  ~  5 
The  result  may  be  checked  by  another  counting  after  seeding.     If  the  result  is  in- 
correct, either  more  liquid  or  more  cells  must  be  added.    -But  in  exact  work  this 
contingency  does  not  arise. 

Suppose  it  is  wished  to  sow  ai  cells  of  a  yeast  species  /I,  and  bi  cells  of  a  species  B 
in  a  flask  containing  p  c.c.  of  culture  liquid,  from  two  seeding  liquids  containing  a 
and  b  cells  per  unit  of  volume  respectively.  The  number  of  cubic  centimeters  x 
and  y,  to  be  sown  from  A  and  B  respectively,  is  found  from  the  following  equations. 

a^  ^  p  +  x  +  y       ,  ^*  ^  P  +  x  +  y 
ai  X  bi  y 

the  quantity  of  liquid  after  infection  being  p  +  x  +  y;  from  this  we  find: 

_  aibp  _  abip 

ab  —  Oib  —  aibi  ab  —  Oib  —  aibi 

Combinations  of  the  above  three  cases  may  of  course  occur  but  from  the  explana- 
tions given  here  it  will  not  be  difficult  to  solve  them. 


622 


LABORATORY   EXERCISES 
LESSON  21 


Cidtivalion  of  Yeasts  on  Gypsum  Blocks.- — Spore  Cultivation. — Blocks  of  gypsum 
are  used  generally  for  the  cultivation  of  the  spores  of  the  yeasts.  The  block  is  in 
the  form  of  a  truncated  cone,  and  the  cover  of  the  vessel  fits  quite  loosely.  The 
dishes  used  in  the  Carlsberg  laboratory  are  the  so-called  bird  troughs  (Vogelnapfe) . 


Fig.   219. — Method  of  pouring  gelatin  into  Petri  dishes.      {After  Lohnis.) 


A  suitable  size  for  these,  taking  outside  measurements,  is  as  follows:  height  4.5  to 
S  cm.;  diameter  of  the  bottom  about  7  cm.  The  gypsum  block  is  3  cm.  high;  the 
diameter  of  the  lower  surface  is  5.3  cm.,  that  of  the  upper  surface  3.8  cm.  To  make 
a  gypsum  block,  2  parts  of  powdered  gypsum  are  mixed  with  %  part  of  water  and  the 
mixture  poured  into  a  tin  mould.  The  block  should  be  hard,  and  the  mould  must 
not  be  rubbed  with  fat,  oil  or  such  material.     A  culture  on  a  gypsum  block  in  such 


Fig. 


-Petri  dish.      {After  Williams  in  Schneider,  Pharmaceutical  Bacteriology, 
p.  S9-) 


a  vessel  cannot,  as  a  rule,  be  kept  free  from  bacterial  infection,  for  the  cover  must 
not  be  closed  down  tightly,  but  should  allow  free  access  of  the  air.  The  dishes  with 
gypsum  blocks  are  sterilized  for  one  to  one  and  a  half  hours  at  110°  to  ii5°C.,  the 
dishes  first  being  wrapped  in  a  crepe  napkin  or  in  filter  paper.  The  gypsum  blocks 
are  sterilized  in  a  moist  condition  before  planting  the  yeast  on  their  upper  surface. 
The  gypsum  blocks  can  be  used  several  times. 

Method  of  Pouring  Plates  (Fig.  219). — Place  three  sterile  Petri  dishes  (Fig.  220) 


LABORATORY   AND    TEACHING   METHODS  623 

in  a  row  after  previously  sterilizing  them  wrapped  in  a  crepe  napkin  in  the  hot-air 
oven. 

Take  three  sterile  test  tubes  numbered  i,  2  and  3  and  fill  with  the  liquefied 
nutrient  to  be  used.  Plug  each  tube  with  cotton  and  flame  the  plugs,  which  should 
be  removed  readily  from  the  mouths  of  the  tubes. 

Add  one  loopful  of  inoculum  to  tube  No.  i.  After  replugging,  rotate  the  tube 
between  the  palms  of  the  hands  with  an  even  circular  movement  to  diffuse  the  in- 
oculum throughout  the  medium;  avoid  jerky  movements  as  these  cause  bubbles 
of  air  to  form  in  the  medium. 

Sterilize  the  platinum  loop  and  add  two  loopfuls  of  diluted  inoculum  to  tube 
No.  2  and  mix  as  before.  In  a  similar  manner  transfer  three  loopfuls  of  liquefied 
medium  from  tube  No.  2  to  tube  No.  3  and  mix  thoroughly. 

Flame  the  plug  of  tube  No.  i,  remove  it,  then  flame  the  lips  of  the  tube;  slightly 
raise  the  cover  of  Petri  dish  No.  i,  introduce  the  mouth  of  the  tube;  then  elevate 
the  bottom  of  the  tube,  pour  the  liquefied  medium  into  the  Petri  dish  to  form  a  thin 
layer.  Remove  the  mouth  of  the  tube  and  close  the  "plate."  If  the  medium  has 
failed  to  flow  evenly  over  the  bottom  of  the  plate,  raise  the  plate  and  tilt  it  to  rectify 
the  fault. 

Pour  plates  No.  2  and  No.  3  in  a  similar  manner  from  tubes  Nos.  2  and  3.  Label 
the  plates  with  the  distinctive  name  or  number  of  the  inoculum,  the  number  of  the 
dilution,  also  the  date. 

In  this  way  colonies  may  be  obtained  quite  pure  and  separate  from  each  other. 
They  may  be  described  as  such,  and  may  then  be  transferred  as  pure  cultures  to 
other  media  in  other  test-tubes. 

In  plate  No.  i  probably  the  colonies  will  be  so  numerous  and  crowded,  and  there- 
fore so  small,  as  to  render  it  useless.  In  plate  No.  2  they  will  be  more  widely  sepa- 
rated, but  usually  No.  3  is  the  plate  reserved  for  careful  examination,  as  in  this  the 
colonies  are  usually  widely  separated,  few  in  number  and  large  in  size. 

Agar  plates  are  poured  in  a  similar  manner,  but  the  agar  must  be  melted  in  boil- 
ing water  and  then  allowed  to  cool  to  42°C.  or  45°C.  in  a  carefully  regulated  water 
bath  before  being  inoculated  and  the  entire  process  must  be  carried  out  very  rapidly 
otherwise  the  agar  will  have  solidified  before  the  operation  is  completed.  After 
the  agar  has  hardened  it  is  incubated  at  37°C.  and  the  plates  are  inverted  as  this 
prevents  flooding  of  the  agar  surface  by  the  squeezing  out  of  the  water  of  condensa- 
tion as  the  agar  hardens.     Gelatin  plates  are  not  inverted. 

Streak  Method. — The  isolation  of  pure  cultures  of  organisms  by  the  streak 
method  differs  from  the  plate  method  in  that  the  medium  (gelatin,  agar,  blood 
serum)  is  not  inoculated  in  the  fluid  state  but  the  necessary  dflution  to  secure  iso- 
lated colonies  is  secured  by  drawing  a  glass  rod  with  its  end  bent  into  a  triangle, 
as  recommended  by  Bergey,  several  times  across  the  surface  of  the  sterile  medium 

in  Petri  dishes  by  lifting  the  cover  while  so  doing.     The <^  glass  rod 

has  been  previously  infected  with  the  material  to  be  studied  qualitatively.  It  is 
preferable,  according  to  Bergey,  to  place  a  small  quantity  of  the  mixed  culture 
in  the  center  of  the  first  plate  of  a  series,  and  thence  distribute  the  material 
over  three  or  more  plates  in  succession  with  the  glass  spreader.  Eventually  a 
degree  of  dilution  is  reached  where  distinct  colonies  are  in  evidence. 


624 


LABORATORY   EXERCISES 


LESSON  22 

Isolation  of  a  Leaf  Wilt  Fungus  in  Pure  Culture. — Given  a  fungus  causing  leaf 
wilt,  to  obtain  a  pure  culture  by  excluding  the  non-pathogenic  forms. 

I.  Look  for  the  fruiting  stage  of  the  suspected  fungus,  or  fungi.  Transfer  some 
of  the  spores  with  a  sterile  needle  into  a  tube  of  5  c.c.  of  sterile  water.  (If  pycnidia 
or  perithecia  are  present,  transfer  a  whole  pycnidium  or  perithecium  into  sterile 
water,  and  crush  the  fruit  body  to  cause  the  escape  of  the  spores).  Then  with  a 
sterile  needle  transfer  some  of  the  water  with  the  spores  into  a  tube  of  agar-agar 
which  is  made  liquid  by  putting  in  a  vessel  of  hot  water  and  then  allowed  to  cool. 
This  tube  is  marked  A.  Then  from  tube  A  transfer  a  drop  of  agar  with  a  sterile  needle 
to  another  similar  test-tube  with  liquid  agar  designated  as  B  (Fig.  221).  Then 
perform  the  same  sort  of  transfer  to  a  third  tube  C.  Distilled  water  or  nutrient 
bouillon  can  be  used  for  these  dilutions  instead  of  agar. 


Fig.  221.  Fig.  222. 

Fig.  221. — Method  of  holding  test-tubes  in  transfer  of  fungi  from  one  test-tube 
to  another.      {After  Lohnis.) 

Fig.  222. — Cylindric  form  of  wire  basket  for  holding  test-tubes  during  steriliza- 
tion and  other  operations.      {After  Schneider,  Pharmaceutical  Bacteriology,  p.  37.) 

^,  J5  and  C  are  thoroughly  shaken  and  each  is  transferred  to  Petri  dishes  marked 
A,  B  and  C.  If  water  is  used  to  dilute,  or  bouillon,  it  must  be  mixed  with  the  material 
poured  into  the  Petri  dishes.  These  are  observed  for  any  growth  that  may  take  place 
on  the  surface  of  the  agar-agar.  Transfers  are  made  from  the  single  colonies  into 
agar  slants  in  test-tubes. 

If  no  spore  forms  are  present,  cut  out  pieces  of  the  affected  leaf  and  place  in  a 
tube  containing  i  per  cent,  mercuric  chloride  diluted  in  equal  amounts  in  50  per  cent, 
alcohol.  Shake  the  tube  so  that  the  material  is  bathed  in  the  disinfectant.  Do 
this  for  half  a  second  to  two  minutes  according  to  the  thickness  of  the  leaf.  Pour 
off  the  disinfectant  and  wash  the  material  three  times  in  sterile  water,  care  being 
taken  to  keep  out  foreign  infection.  Then  with  a  sterile  forceps,  take  each  piece 
of  the  material  and  crush  it  thoroughly  at  the  mouth  of  a  tube  containing  melted 


LABORATORY   AND    TEACHING   METHODS  625 

;ind  cooled  agar.  When  the  materuU  is  crushed,  it  is  well  shaken  up  with  agar  and 
the  whole  poured  into  a  Petri  dish.  If  the  growth  of  one  fungus  appears,  it  means 
that  we  have  the  parasite  in  captivity,  or  pure  culture.  If  more  than  one  fungus 
is  obtained,  they  must  all  be  transferred  separately  into  agar  slants  in  test-tubes 
and  tested  by  inoculation  for  their  pathogenicity.  The  true  pathogen  is  of  course 
the  one  which  will  reproduce  all  of  the  symptoms  of  the  disease. 

Note. — To  keep  out  bacterial  infection  put  one  drop  of  a  5  per  cent,  lactic  acid 
in  each  of  the  agar  tubes  used  in  making  the  cultures. 

Differential  Methods  of  Isolation 

Pasteurization  and  Sterilization. — In  order  to  compare  the  effect  of  these  two 
operations  on  organic  material,  take  some  milk  and  pasteurize  part  of  it  and  sterilize 
the  other  part  by  one  sterilization.  Conduct  both  operations  in  previously  sterilized 
flasks  plugged  with  cotton  after  the  milk  is  introduced  (Fig.  223). 

Milk  is  pasteurized  by  heating  it  up  to  a  temperature  of  8s°C.  followed  by  a 
rapid  cooling.  Milk  is  sterilized  by  heating  up  to  ioo°C.  for  five  minutes.  Set 
the  flasks  aside  and  compare.     Note  any  changes  that  may  take  place. 

Differential  Media. — (a)  Selective. — Some  media  are  specially  suitable  for  cer- 
tain species  of  bacteria  and  enable  them  to  overgrow  and  finally  choke  out  other 
varieties. 

{b)  Deterrent. — The  converse  of  the  above  also.  Certain  media  possess  the 
power  of  inhibiting  the  growth  of  a  greater  or  less  number  of  species.  For  instance, 
media  containing  carbolic  acid  to  the  amount  of  i  per  cent,  will  inhibit  the  growth 
of  practically  everything  but  the  Bacillus  coli  communis. 

Differential  Sterilisation. — (a)  Non-sporing  Bacteria. — Similarly,  advantage  may 
be  taken  of  the  varying  thermal  death  points  of  bacteria.  From  a  mixture  of  two 
organisms  whose  thermal  death  points  differ  by,  say,  4°C. — e.g.,  Bacillus  pyocyanens, 
thermal  death  point  5S°C.,  and  Bacillus  mese7itericus  vulgatus,  thermal  death  point 
6o°C. — a  pure  cultivation  of  the  latter  may  be  obtained  by  heating  the  mixture  in 
a  water  bath  to  58°C.  and  keeping  it  at  that  point  for  ten  minutes.  The  mixture 
is  then  planted  on  to  fresh  media  and  incubated,  w^hen  the  resulting  growth  will  be 
found  to  consist  entirely  of  B.  mescntericus. 

{b)  Sporing  Bacteria. — This  method  is  found  to  be  of  even  greater  practical  value 
when  applied  to  the  differentiation  of  a  spore-bearing  organism  from  one  which 
does  not  form  spores.  In  this  case  the  mixture  is  heated  in  a  water  bath  at  8o°C. 
for  fifteen  to  twenty  minutes.  At  the  end  of  this  time  the  non-sporing  bacteria  are 
dead,  and  cultivations  made  from  the  mixture  will  yield  only  a  growth  resulting 
from  the  germination  of  the  spores  only. 

differential  atmosphere  cultivation 

Aerobic  and  Anaerobic. — For  the  separation  of  bacteria,  it  is  possible  to  draw  the 
line  between  those  that  need  oxygen  for  growth  (aerobic)  and  those  that  will  grow 
without  ox>'gen  (anaerobic).     By  excluding  oxygen,  anaerobic  forms  alone  develop. 

Inoculation  into  various  animals  or  plants  may  be  used  as  a  means  of  separation. 
40 


626  LABORATORY   EXERCISES 

LESSON  23 
Walcr  Analysis. 

I.  Collect  water  from  tap  in  a  sterile  Erlenmeyer  flask,  allowing  H2O  to  run  for 
ten  minutes  before  collecting. 

II.  Melt  two  tubes  of  gelatin  at  42°C. 

III.  Add  to  tube  No.  A  o.i  c.c.  and  tube  No.  2  0.2  c.c.  from  the  flask.  Shake 
to  mix  H2O  with  gelatin. 

IV.  Pour  in  Petri  dishes  No.  A  and  B  and  place  in  locker. 

V.  Count  colonies  which  develop  at  end  of  twenty-four  and  forty-eight  hours. 

VI.  Estimate  the  number  of  colonies  which  would  have  developed  in  i  c.c.  of 
water. 

Example. 

Twenty-four  hours 

50  colonies  have  developed  on  plate  No.  A — 50  X  10  =  500  in  i  c.c. 
96  colonies  have  developed  on  plate  No.  B — 96  X    5  =  480  in  i  c.c. 

2)980 

490  in  I  c.c. 

Forty-eight  hours 

62  colonies  have  developed  on  plate  No.  A — 62  X  10  =  620  in  i  c.c. 
102  colonies  have  developed  on  plate  No.  B — 102  X  5  =  510  in  i  c.c. 

2)1130 

565  in  I  c.c. 

LESSON  24 

METHODS  OF  IDENTIFICATION 

Descriptive  Terms. — For  complete  details  consult  Eyre,  J.  W.  H. :  The  Elements 
of  Bacteriological  Technique,  1902:  208. 

Types  of  Colonies 

A.  Size. — The  size  of  the  cells  and  the  spores  at  various  ages. 

B.  Shape. — Punctiform,  round,  elliptic,  irregular,  fusiform,  cochleate,  amoeboid, 
mycelioid,  filamentous,  floccose,  rhizoid,  conglomerate,  toruloid,  rosulate. 

C.  Surface  Elevation. — Flat,  convex,  capitate,  umbonate,  effused,  pulvinate, 
umbilicate,  raised. 

D.  Character  of  Surface.- — Smooth,  alveolate,  punctate,  bullate,  vesicular, 
verrucose,  squamose,  echinate,  papillate,  rugose,  corrugated,  contoured,  rimose. 

E.  Internal  Structure  of  Colony  (Microscopic). — Refraction  weak,  refraction 
strong,  amorphous,  hyaline,  homogeneous,  homochromous,  finely  granular,  coarsely 
granular. 


LABORATORY  AND  TEACHING  METHODS 


627 


F.  Optic  Characters. — Transparent,  vitreous,  oleaginous,  resinous,  translucent, 
porcelaneous,  opalescent,  nacreous,  sebaceous,  butyrous,  cetaceous,  opaque,  creta- 
ceous, dull,  glistening,  fluorescent,  iridescent,  color  of  colonies. 

G.  Edges  of  Colonies. — Entire,  undulate,  repand,  erose,  lobulate,  auriculate, 
lacerate,  fimbriate,  ciliate. 


^iy 


Pig.  223. — Types  of  growth  in  stab  cultures.  A,  Non-liquefyinp;  i,  Filiform 
{Bacidiis  coli);  2,  beaded  {Streptococcus  pyogenes);  3,  echinate  {Bacterium  acidi 
lactici);  4,  villous  {Bacterium  murisepticiim);  5,  arborescent  {Bacillus  mycoides). 
B,  Gelatin  liquefying.  6,  Crateriform  {Bacillus  vulgare,  24  hr.) ;  7,  napiform  {Bacillus 
sublilis,  48  hr.);  8,  infundibuliform  {Bacillus  prodigiosus) ;  9,  saccate  {Microspira 
Finkleri);  10,  stratiform  {Pseudomonas  flavescens).  {From  McFarland  after  Frost  in 
Schneider,  Albert:  Bacteriological  Methods  in  Food  and  Drug  Laboratories,  1915:  87.) 


TYPES   OF   STAB   CULTURES 


A.  Surf  ace  Growth. — Filiform,  beaded,  echinate  villous,  arborescent. 

B.  Character  of  Liquefied  Gelatin. — Pellicle  on  surface,  uniformly  turbid,  granular, 
mainly  clear  but  containing  flocculi,  deposit  at  apex  of  liquefied  portion,  production 
of  gas  bubbles. 

C.  Area  of  Liquefaction  (if  present). — Crateriform,  saccate,  infundibuliform, 
napiform,  fusiform,  stratiform  (Fig.  223). 


628  LABORATORY   EXERCISES 


LESSON  25 


Plate  Counter. — The  most  accurate  method  of  counting  the  colonies  on  each  of 
the  plates  is  by  means  of  the  counting  disk.  These  disks  consist  of  a  piece  of  paper, 
upon  which  is  printed  a  dead  black  disk,  subdivided  by  concentric  circles  and  radii 
painted  in  white.  In  Jeffer's  counter  each  subdivision  has  an  area  of  i  sq.  cm.:  in 
Pake's  counter,  radii  divide  the  circle  into  sixteen  equal  sectors,  and  counting  is 
facilitated  by  equidistant  concentric  circles.     (For  disks  see  Eyre,  p.  322.) 

(a)  In  the  final  counting  of  each  plate,  place  the  Petri  dish  over  the  counting 
disk,  and  center  it,  if  possible,  making  its  periphery  coincide  with  one  or  other  of  the 
concentric  circles. 

{h)  By  means  of  a  hand  lens  count  the  colonies  appearing  in  each  sector  in  turn. 
Make  a  note  of  the  number  present  in  each. 

(c)  If  the  colonies  present  are  fewer  than  500  the  entire  plate  should  be  counted. 
If,  however,  they  exceed  this  number,  enumerate  one-half,  or  one-quarter  of  the 
plate,  or  count  a  sector  here  and  there,  and  from  these  figures  estimate  the  number 
of  colonies  present  on  the  entire  plate. 

Jeffers'  counting  plate^  (Fig.  224)  consists  of  concentric  zones  which  are  divided 
into  small  sections,  each  having  an  area  of  i  sq.  cm.  To  determine  the  position  of 
the  circles  marked  10,  20,  the  position  of  the  circles  marked  10,  20,  40,  60,  100  and 
140  in  the  diagram,  whose  areas  equal  10,  20,  40,  60,  100  and  140  sq.  cm.  respectively, 
the  formula,  wr"^  =  area,  was  used.  In  order  to  show  the  application  of  the  formula, 
the  radius  of  the  circle  whose  area  is  equal  to  10  sq.  cm.,  will  be  found  from  the  formula 
as  follows: 

TT    =    3.I416. 

irr-  =  10  or  r^  =  10  -i-  tt. 
10  -^  3-1416  =  3.18309  or  r-. 
\/3-i8309  =  1.78-f  or  r. 

1.78  +  cm.  =  the  radius  of  a  circle  whose  area  is  10  sq.  cm.  Dividing  the  circle 
into  ten  equal  sectors,  each  sector  has  an  area  equal  to  i  sq.  cm.  By  the  same 
method  we  find  the  radius  of  a  circle  whose  area  equals  20  sq.  cm.  thus  making  each 
of  the  ten  spaces  between  circles  10  and  20  and  bounded  laterally  by  the  ten  radii 
equal  to  i  sq.  cm.  We  next  construct  a  circle  whose  area  equals  40  sq.  cm.  and  divide 
each  sector  as  far  as  circle  20,  making  twenty  equal  areas  between  circles  20  and  40, 
each  equal  to  i  sq.  cm.  In  like  manner  we  construct  circles  60,  100  and  140  divid- 
ing the  sectors  in  the  zone  lying  between  circles  60  and  140  to  produce  areas  equal 
to  I  sq.  cm.  each.  If  a  plate  whose  area  is  greater  than  140  sq.  cm.  is  used,  a  circle 
whose  area  is  180  sq.  cm.  can  be  drawn  and  the  radiating  lines  extended  out  to  the 
circle  (Fig.  224). 

The  Petri  dish  can  be  centered  upon  this  apparatus  by  the  circles  and  the  area 
read  from  the  line  its  edges  approach.  To  facilitate  the  reading  of  the  area  of  the 
plate  the  circles  80  and  120,  whose  areas  are  equal  to  80  and  120  sq.  cm.,  respectively, 

1  Jeffers,  H.  W.  :  An  Apparatus  to  Facilitate  the  Counting  of  Colonies  of 
Bacteria  on  Circular  Plates.     Journ.  Applied  Micros.,  I:  53-54,   March,  1898. 


LABORATORY  AND  TEACHING  METHODS 


629 


were  drawn  as  dotted  circles,  thus  making  the  areas  marked  "a"  and  "6"  equal  to 
0.5  sq.  cm.  The  colonies  in  several  areas  can  be  counted,  an  average  taken,  and  the 
result  multiplied  by  the  number  of  square  centimeters  in  each  plate. 

A  fine  apparatus  could  be  made  by  covering  a  plate  of  glass  with  a  uniform  layer 
of  wax  and  with  a  sharp  instrument  cut  the  figure  in  the  wax  and  subject  it  to  hydro- 
fluoric acid  for  a  few  minutes  which  would  etch  the  glass  where  exposed.     Cleaning 


Fig.  224. — Jeffer's  circular  counting  plate  for  Petri  dish  cultures.  The  entire 
area  (100  sq.  cm.)  is  marked  off  into  the  equal  sectors  of  ten  sq.  cm.  each.  {After 
Schneider,  Pharmaceutical  Bact.  p.  90.) 


off  the  wax  and  placing  the  glass  plate  over  black  velvet,  the  colonies  could  easily 
be  counted. 

Neisser's  Marking  and  Counting  Apparatus  for  Bacterial  Colonics. — The  apparatus 
is  employed  for  counting  bacterial  colonies  and  for  marking  off  their  position. 

When  in  nsC  the  apparatus  is  mounted  on  the  lid  of  the  box  with  which  it  is 
supplied,  thus  the  latter  serves  at  the  same  time  as  a,  base. 


630  LABORATORY   EXERCISES 

For  this  purpose  a  metal  guide  plate  is  screwed  on  to  the  inside  of  the  lid,  which 
latter  is  reversed  when  the  instrument  is  arranged  for  use  and  the  marking  apparatus 
is  placed  on  this  plate.  This  apparatus  consists  of  a  vertical  pillar  with  square  base 
plate  and  a  metal  frame  which  is  vertically  adjustable  by  means  of  a  rack  and  pinion. 
The  horizontal  movement  is  obtained  by  moving  the  entire  dish  carrier  along  the 
guide  plate  which  is  screwed  on  to  the  box  lid. 

The  Petri  dish  is  secured  in  the  frame  by  means  of  two  milled  heads  which  are 
fixed  on  the  right-hand  side  and  at  the  bottom. 

Immediately  behind  the  Petri  dish  is  mounted  a  glass  screen  divided  into  squares, 
which  as  a  further  aid  to  localization,  are  subdivided  and  numbered. 

A  second  pillar  is  screwed  into  the  lid  in  front  of  the  dish  holder  and  carries  the 
lens.     The  lens  is  vertically  adjustable  and  is  threaded  for  focusing  purposes. 

Below  the  lens  carrier  is  fitted  a  horizontal  bar  which  serves  as  a  hand  rest  when 
marking  ofT  the  colonies. 

A  special  counting  screen  is  provided  with  fifteen  square  openings  arranged  in  a 
V-shape  (echelon)  by  means  of  which  the  number  of  colonies  at  four  places  in  sixty 
squares  may  be  determined. 

At  the  upper  edge  of  the  counting  screen  lines  are  ruled  which  serve  as  scales  for 
the  Petri  dish;  the  numbers  on  the  one  side  indicate  the  diameters  in  millimeters 
corresponding  to  each  scale  line,  while  the  numbers  on  the  other  side  indicate  how 
many  times  the  area  of  the  sixty  squares  is  contained  in  the  area  of  the  whole  Petri 
dish.  Thus  in  order  to  ascertain  the  total  number  of  colonies  in  the  dish,  it  is  only 
necessary  to  count  the  number  of  colonies  in  the  sixty  squares  and  to  multiply  the 
figure  thus  obtained  by  the  proportional  number  required  by  the  diameter  of  the  dish. 

LESSON  26 

LABORATORY   WORK   IN   SYSTEMATIC  BACTERIOLOGY 

As  it  is  important  for  students  in  mycology  to  be  able  to  identify  the  various 
species  of  bacteria,  which  they  may  meet  in  their  investigation  of  the  fungi,  the  fol- 
lowing suggestions  are  made  as  to  the  systematic  study  of  the  forms  of  bacterial 
life.  Ordinarily,  where  the  other  groups  of  fungi  are  to  be  considered,  time  will  not 
permit  a  detailed  systematic  study  of  the  bacteria  where  cultural  methods  are  re- 
quired in  the  identification  of  the  specific  forms.  Yet  much  can  be  done  in  the  class- 
room with  the  microscope  in  the  study  of  the  morphology  of  selected  species.  The 
following  exercises  are  presented  as  suggestions  to  the  teacher  and  student  of 
mycology. 

First  Exercise.— The  teacher  can  distribute  to  each  member  of  the  class  a  selected 
number  of  bacteria  in  culture  tubes.  Each  tube  should  be  numbered,  so  that  the 
student,  after  determining  the  generic  character  of  the  different  organisms  handed 
to  him,  can  attach  the  number  to  his  specific  determinations,  so  that  the  teacher 
can  check  off  the  results  of  each  student's  work  by  the  numbered  list  of  species 
kept  for  such  classroom  work.  The  bacteria  from  each  of  the  culture  tubes  should  be 
mounted  in  balsam  after  staining  with  carbol  fuchsin,  or  some  other  approved  stain, 
and  kept  for  future  reference  and  study. 


LABORATORY    AND    TEACHING    METHODS  63 1 

Second  Exercise. — The  members  of  the  class  can  raise  material  for  such  morpho- 
logic study  after  tlie  first  exercise  has  been  completed  by  partially  filling  test-tubes 
with  such  materials  as  chopped  hay,  prunes,  lima  beans,  split  peas,  cracked  oats  and 
cabbage  leaves,  adding  water,  and  treating,  as  follows: 

One  set  of  tubes  should  be  plugged  and  thoroughly  sterilized  by  differential 
sterilization.  This  experiment,  after  examination  of  the  material  under  the  micro- 
scope, demonstrates  that  bacterial  growth  in  the  tubes  does  not  take  place. 

A  second  set  of  test-tubes  can  be  left  open  to  the  air  after  the  water  and  the 
culture  material  have  been  completely  sterilized.  This  gives  the  organisms  that 
come  from  the  air. 

A  third  set  of  tubes  can  be  partially  filled  with  water,  plugged  and  then  sterilized, 
and  after  sterilization  unsterilized  material  can  be  added.  This  gives  the  organisms 
that  enter  through  the  vegetable  substance. 

A  fourth  set  of  tubes  can  be  filled  with  the  culture  material,  plugged  and  steril- 
ized. Unsterilized  water  can  be  then  added  to  each  of  these  tubes.  This  gives  the 
microbes  that  come  in  through  the  water.  These  are  rough  methods  adapted  to 
general  class  work,  and  in  each  case  the  organisms  which  appear  should  be  mounted 
and  systematically  studied  to  determine  the  different  generic  forms  which  are  present, 
as  far  as  that  can  be  done  by  staining  methods  and  the  microscope. 

Third  Exercise. — The  teacher  can  distribute  material  of  diseased  plants  in  which 
the  disease  is  directly  traceable  to  some  bacterial  organism.  For  this  exercise,  the 
professor  should  have  a  stock  of  at  least  a  half  dozen  diseased  plants  properly  fixed 
and  preserved  in  50  per  cent,  alcohol.  The  material,  which  has  been  distributed, 
should  be  cut  free-hand  by  the  student  and  the  sections  mounted  as  directed,  or  the 
student  can  imbed  the  material  in  celloidin,  or  in  paraflan,  to  secure  thinner  serial 
sections  by  the  use  of  a  sliding,  or  rotary  microtome.  To  carry  on  this  exercise,  the 
student  should  have  an  acquaintance  with  celloidin  and  paraffin  technique. 

Fourth  Exercise. — Where  the  student  has  plenty  of  time  and  expects  to  specialize 
in  the  study  of  the  bacterial  diseases  of  plants,  then  he,  or  she,  should  follow  the 
following  scheme  suggested  by  Chester  in  his  "Manual  of  Determinative  Bacterio- 
logy," the  descriptions  and  keys  of  which  can  be  used  in  a  detailed  systematic 
study  of  bacterial  organisms.  This  exercise  can  be  pursued  only  after  the  student 
has  learned  cultural  and  isolation  methods  and  not  at  the  beginning  of  a  course  in 
mycology  and  its  technique. 

LESSON  27 

Scheme  for  the  Study  of  Bacteria. — The  Society  of  American  Bacteriologstis  has 
adopted  a  numeric  system  of  recording  the  salient  characters  of  an  organism  (group 
number). 

100 Endospores  produced. 

200 Endospores  not  produced. 

10 Aerobic  (strict). 

20 Facultative  anaerobic. 

30 Anaerobic  (strict). 


632  LABORATORY   EXERCISES 

I Gelatin  liquefied. 

2 , Gelatin  not  liquefied. 

0.1 Acid  and  gas  from  dextrose. 

0.2 Acid  without  gas  from  dextrose. 

0.3 No  acid  from  dextrose. 

0.4 No  growth  with  dextrose. 

o.oi Acid  and  gas  from  lactose. 

o. 02 Acid  without  gas  from  lactose. 

o. 03 No  acid  from  lactose. 

0.04 No  growth  with  lactose. 

o. 001 Acid  and  gas  from  saccharose. 

o.  002 Acid  without  gas  from  saccharose. 

o. 003 No  acid  from  saccharose. 

0.004 No  growth  with  saccharose. 

o.oooi Nitrates  reduced  with  evolution  of  gas. 

o. 0002 Nitrates  not  reduced. 

0,0003 Nitrates  reduced  without  gas  formation. 

o .  ooooi Fluorescent. 

o. 00002 Violet  chromogens. 

o .  00003 Blue  chromogens. 

o .  00004 Green  chromogens. 

0.00005 Yellow  chromogens. 

0.00006 Orange  chromogens. 

o. 00007 Red  chromogens. 

0.00008 Brown  chromogens. 

o .  00009 Pink  chromogens. 

o .  00000 Non-chromogens. 

o.  oooooi Diastatic  action  on  potato  starch  (strong). 

o.  000002 Diastatic  action  on  potato  starch  (feeble). 

o.  000003 Diastatic  action  on  potato  starch  (absent). 

o. ooooooi Acid  and  gas  from  glycerin. 

0.0000002 Acid  without  gas  from  glycerin. 

o .  0000003 No  acid  from  glycerin. 

o .  0000004 No  growth  with  glycerin. 

The  genus,  according  to  the  system  of  Migula,  is  given  its  proper  symbol  which 
precedes  the  member  thus:  According  to  the  above  the  symbol  of  Bacillus  coli 
would  be  B.  222.111102  and  of  Pseudomonas  campeslris  Ps.  211.333151.  This  will 
be  found  useful  as  a  quick  method  of  showing  close  relationships  inside  the  genus, 
but  is  not  a  sufficient  characterization  of  any  organism.  The  descriptive  chart  of 
the  Society  of  American  Bacteriologists  of  which  the  above  decimal  system  forms 
a  part  will  be  found  useful  in  the  detailed  systematic  study  of  the  bacteria.  It  was 
prepared  by  F.  D.  Chester,  F.  P.  Gorham  and  Erwin  F.  Smith,  appointed  as  a 
committee  on  methods  of  identification  of  bacterial  species.  Their  report  was 
endorsed  by  the  society  at  the  annual  meeting,  December,  1907. 


LABORATORY   AND    TEACHING   METHODS  633 

LESSON  28 

The  detailed  investigation  of  the  bacteria  and  other  fungous  organisms,  as  out- 
lined below,  can  be  undertaken  only  after  the  student  has  become  acquainted  with 
the  cultural  methods  given  in  another  section  of  this  handbook,  but  the  table  adopted 
by  the  Society  of  American  Bacteriologists  is  given  below,  because  it  fits  into  the 
general  discussion  and  study  of  the  classification  previously  given. 

I.  MORPHOLOGY. 

1.  Vegetative  Cells. — Medium  used 

temp ,  age ,  days 

Form,  round,  short  rods,  long  rods,  short  chains,  long  chains,  filaments,  commas, 
short  spirals,  long  spirals,  Clostridium,  cuncate,  clavate,  curved. 

Limits  of  size 

Size  of  majority 

Ends,  rounded,  truncate,  concave. 

I  Orientation  (grouping) 

Agar  I  Chains  (number  of  elements) 

hanging  block      I       Short  chains,  long  chains. 

[  Orientation  of  chains,  parallel,  irregular. 

2.  Sporangia. — Medium  used 

temp 

Form,  elliptic,  short  rods,  spindled,  clavate,  drum-sticks. 

Limits  of  size 

Size  of  majority 

Location  of  endospores,  central,  polar. 

3.  Endospores. — Form,  round,  elliptic,  elongated. 

Limits  of  size 

Size  of  majority 

Wall,  thick,  chin. 

Sporangium  wall,  adherent,  non-adherent. 
Germination,  equatorial,  oblique,  polar,  bipolar. 

4.  Flagella. — No Attachment,  polar,  bipolar  perilrichiate. 

How  stained 

5.  Capsules. — Present  on 

6.  ZOOGLCEA,  PSEUDOZOOGLCEA. 

7.  Involution  Forms. — On in days  at .°C. 

8.  Staining  Reactions. — i  :  10  watery  fuchsin,  gentian  violet,  carbol  fuchsin 
Loeffler's  alkaline  methylene-blue. 

Special  stains 

Gram Glycogen 

Fat Acid-fast 

Neisser. 

IL  CULTURAL  FEATURES 

I,  2,  3.  Agar  Stroke,  Potato,  Loeffler's  Blood-serum. — 
Growth,  invisible,  scanty,  moderate,  abundant. 


634 


LABORATORY   EXERCISES 


Form  of  growth,  filiform,  cchinulatc,  beaded,  spreading,  plumose,  arbores- 
cent, rhizoid  (Fig.  225). 

Elevation  of  growth,  jial,  effuse,  raised,  convex. 

Luster,  glistening,  dull,  cretaceous. 

Topography,  smooth,  contoured,  rugose,  verrucose. 

Optic  characters,  opaque,  translucent,  opalescent,  iridescent. 

Chromogenesis, 

Odor,  absent,  decided,  resembling 

.Consistency,  slimy,  butyrous,  viscid,  membranous,  coriaceous,  brittle. 

Medium,  grayed,  browned,  reddened,  blued,  greened. 

Liquefaction    (Loefifler's    biood-serum)    begins   in days,    complete 

in days. 

Agar  Stab,  Gelatin  Stab. — Growth,  uniform,  best  at  top,  best  at  bottom, 
surface  growth  scanty,  abundant;  restricted,  widespread. 


Fig.  225. — Types  of  streak  culture,  i,  Filiform  {Bacillus  colt);  2,  echinulate 
(Bacterium  acidi  lactici);  3,  beaded  {Streptococcus  pyogenes);  4,  effuse  {B.  vulgaris); 
5,  arborescent  {Bacillus  mycoides).  {From  McFarland,  after  Frost  in  Schneider, 
Albert:  Bacteriological  Methods  in  Food  and  Drug  Laboratories,  1915:  89.) 


Line  of  puncture,  filiform,  beaded,  papillate,  villous,  plumose,  arborescent. 
Liquefaction,    crateriform,    napiform,    infundibidiform,    saccate,    stratiform, 

begins  in days,  complete  in days. 

Medium,  fluorescent,  browned.] 

6.  Nutrient  Broth.- — Surface  growth,  ring,  pellicle,  flocculent,  membranous,  none. 
Clouding,  slight,  moderate,  strong;  transient,  persistent;  none,  fluid  turbid. 
Odor,  absent,  decided,  resembling 

Sediment,  compact,  flocculent,  granular,   flaky,  viscid  on  agitation,  abundant, 
scant. 

7.  Milk. — Clearing,  without  coagulation. 
Coagulation,  prompt,  delayed,  absent. 

Extrusion  of  whey,  begins  in days. 

Coagulum,  slowly  peptonized,  rapidly  peptonized. 

Peptonization,  begins  on days,  complete  on days 


LABORATORY   AND    TEACHING    METHODS  63 


Reaction,    i   day    ,    2  days    ,  4    days    ,   10    days 

20  days 

Consistency,  slimy,  viscid,  unchanged. 
Medium,  browned,  reddened,  blued,  greened. 
Lab.  ferment,  present,  absent. 

8.  Litmus  Milk. — Acid,  alkaline,  acid  then  alkaline,  no  change.    Prompt  reduction, 
no  reduction,  partial  slow  reduction. 

9,  10.  Gelatin  Colonies.     Agar  Colonies. — Growth,  slow,  rapid. 
(Temperature ) . 

Form,  punctiform,  round,  irregular,  amoehoid,  mycelioid,  filamentous,  rhizoid. 
Surface,  smooth,  rough,  concentrically  ringed,  radiate,  striate. 
Elevation,   flat,    effuse,    raised,    convex   puhinate,    umbonate,    crateriform 
(liquefying). 

Edge,  entire,  undulate,  lobate,  erase,  lacerate,  fimbriate,  floccose,  curled. 
Internal  structure,  amorphous,  finely,  coarsely  granular,  grumose,  filamen- 
tous, floccose,  curled. 
Liquefaction,  cup,  saucer,  spreading. 

11.  Starch  Jelly. — Growth,  scanty,  copious. 
Diastatic  action,  absent,  feeble,  profound. 
Medium  stained 

12.  Silicate  Jelly  (Fermis'  Solution). — Growth,  copious,  scanty,  absent. 
Medium  stained 

13.  Corn's  Solution. — Growth,  copious,  scanty,  absent. 
Medium,  fluorescent,  non-fluorescent. 

14.  Uschinsky's  Solution. — Growth,  copious,  scanty,  absent. 
Fluid,  viscid,  non-viscid. 

15.  Sodium  Chloride  in  Bouillon. — Per  cent,  inhibiting  growth 

16.  Growth  in  Bouillon  over  Chloroform. — Unrestrained,  feeble,  absent. 

17.  Nitrogen. — Obtained    from    peptone,   asparagin,   glycocol,   urea,   ammonia 
salts,  nitrogen. 

18.  Best  media  for  long-continued  growth 

19.  Quick  tests  for  differential  purposes 


636  LABORATORY   EXERCISES 

III.  PHYSICAL  AND  BIOCHEMIC  FEATURES 


I.  Fermentation  Tubes  Containing  Peptone 
Water  or  Sugar-free  Bouillon,  and 

1 

1 

1 

1 

5 

i 

Gas  production  in  per  cent.  (Fig.  226) 

(co;) 

Growth  in  closed  arm 

Amount  of  acid  produced  i  day 

Amount  of  acid  produced,  2  days 

Amount  of  acid  produced,  3  days 

1 

1 

Fig.   226. — Graduated    fermentation    tubes  for    gas    determinations.      {Schneider, 
Pharmaceutical  Bacteriology,  p.  60.) 

2.  Ammonia  Production.- — Feeble,  moderate,  strong,  absent,  masked  by  acids. 

3.  Nitrates  in  Nitrate  Broth. — Reduced,  not  redticed. 

Presence  of  nitrites ammonia 

Presence  of  nitrates free  nitrogen 

4.  Indol  Production. — Feeble,  moderate,  strong. 

5.  Toleration  of  Acids. — Great,  medium,  slight,  acids  tested 

6.  Toleration  of  NaOH. — Great,  medium,  slight. 

7.  Optimum    Reaction  for    Growth   in    Bouillon,  stated  in  Terms   of 
Fuller's  Scale. 


LABORATORY   AND    TEACHING   METHODS 


637 


8.  Vitality  on  Culture  Media. — Brief,  moderate,  long. 

9.  Temperature  Relations. — Thermal  death  point  (ten  minutes  exposure  in 
nutrient  broth  when  this  is  adapted  to  growth  of  organism) °C. 

10.  Killed  readily  by  drying,  resistant  to  drying. 

11.  Per  cent,  killed  by  freezing  (salt  and  crushed  ice  or  liquid  air). 

12.  Sunlight. — Exposure  on  ice  in  thinly  sown  agar  plates;  one-half  plate  cov- 
ered (time  fifteen  minutes),  sensitive,  non-sensitive. 

Per  cent,  killed 

13.  Acids  produced 

14.  Alkalis  produced 

15.  Alcohols 

16.  Ferments. — Pepsin,   trypsin,  diastase,  invertase,  pectasc,  cytase,  tyrosinase, 
oxidase,  peroxidase,  lipase,  catalase,  glucase,  galactase,  lab,  etc. 

17.  Crystals  formed 

18.  Effects  of  Germicides 


Substance     . 

Method  used 

1 

a 

1 

3 

DO 

■3 

III 
14 

1                                                                    j 

IV.  PATHOGENICITY. 

1.  Pathogenic  to  Animals. — Insects,  crustaceans,  fishes,  reptiles,    birds,  mice, 
rats,  guinea  pigs,  rabbits,  dogs,  cats,  sheep,  goats,  cattle,  horses,  monkeys,  man. 

2.  Pathogenic  to  Plants. — 


3.  Toxins. — Soluble,  endotoxins. 

4.  Non-toxin  forming 

5.  Immunity  (bactericidal)." 

6.  Immunity  (non-bactericidal) 

7.  Loss  of  Virulence  on  Culture  Media. 
in months. 


-Prompt,  gradual,  not  observed 


638 


LABORATORY   EXERCISES 


The  Society  of  American  Bacteriologists  has  endorsed  a  brief  characterization 
as  a  part  of  the  descriptive  chart  which  it  has  published.  This  brief  description  is 
useful  in  a  comparative  study  of  different  microorganisms. 

BRIEF  CHARACTERIZATION 

Mark  +  or  o,  and  when  two  terms  occur  on  a  line,  erase  the  one  which  does  not 
apply,  unless  both  apply. 


Diameter  over  in 

heSoc 

3 

1 

« 

.2 

1 

1 
■a 

Gelatin 

Chains,  filaments 

Blood-serum 

1 

o 

Endospores 

Casein 

Capsules 

Agar,  mannite 

Zoogloea,  pseudozoogloea 

Milk 

Acid  curd 

Motile 

Rennet  curd 

Involution  forms 

Casein  peptonized 

Indol 

Gram's  stain 

Hydrogen  sulphid 

1 

o 

Broth 

Cloudy,  turbid 

Ammonia 

Ring 

Nitrates  reduced 

Pellicle 

Fluorescent 

Sediment 

Luminous 

Agar 

Shining 

s 

s 

Animal  pathogen,  epizoon 

Dull 

Plant  pathogen,  epiphyte 

Wrinkled 

Plant  pathogen,  endophyte 

Chromogenic 

Soil 

Gel. 
plate 

Round 

MUk 

Proteus-like 

Fresh  water 

Rhizoid 

Salt  water 

Filamentous 

Sewage 

Curled 

Airi 

Gel. 
stab 

Surface-growth 

Iron  bacterium 

Needle-growth 

Sulphur  bacterium 

Potato 

Moderate,  absent 

Erythro  bacterium^ 

Abundant 

Nitre  bacterium! 

Discolored 

Nodule-producingi 

Starch  destroyed 

w 

ety  of  I 

Fermentation' 

Grows  at  37°C. 

Rettingi 

Grows  in  Cohn's  sol. 

Dairy! 

Grows 
Lddition 

in  Uschinsky's  sol. 
s  to  the  original  chart  of  t 

Pharmaceutic! 
American  Bacteriologists. 

L.4B0RAT0RY    AND    TEACHING    METHODS  639 

Notes. — ^The  morphologic  characters  shall  be  determined  and  described  from 
growths  obtained  upon  at  least  one  solid  medium  (nutrient  agar)  and  in  at  least 
one  liquid  medium  (nutrient  broth).  Growths  at  37°C.  shall  be  in  general  not  older 
than  twenty-four  to  forty-eight  hours,  and  growths  at  2o°C.  not  older  than  forty- 
eight  to  seventy-two  hours.  To  secure  uniformity  in  cultures,  in  all  cases  prelimi- 
nary cultivation  shall  be  practised  as  described  in  the  revised  Report  of  the  Com- 
mittee on  Standard  Methods  of  the  Laboratory  Section  of  the  American  Public 
Health  Association,  1905. 

The  observation  of  cultural  and  biochemic  features  shall  cover  a  period  of  at 
least  fifteen  days  and  frequently  longer,  and  shall  be  made  according  to  the  revised 
standard  methods  above  referred  to.  All  media  shall  be  made  according  to  the  same 
standard  methods. 

Gelatin  stab  cultures  shall  be  held  for  si.x;  weeks  to  determine  liquefaction. 

Ammonia  and  indol  tests  shall  be  made  at  the  end  of  tenth  day,  nitrite  tests  at 
end  of  fifth  day. 

n 

Titrate  with  —  NaOH,  using  phenolphthalein  as  an  indicator;  make  titrations 

at  times  from  blank.     The  difference  gives  the  amount  of  acid  produced. 

The  titration  should  be  done  after  boiling  to  drive  off  any  CO2  present  in  the 
culture. 

Generic  nomenclature  shall  begin  with  the  year  1872  (Cohn's  first  important 
paper).  Species  nomenclature  shall  begin  with  the  year  1880  (Koch's  discovery  of 
the  poured  plate  method  for  the  separation  of  organisms). 

Chromogenesis  shall  be  recorded  in  standard  color  terms. 

LESSON  29 

DIRECTIONS  FOR  THE  STUDY  OF  PATHOGENIC  FUNGI 

The  directions  given  below  for  the  study  of  the  fungi  which  cause  diseases  in 
plants  have  been  made  as  general  as  possible  so  that  the  student  will  find  enough 
flexibility  in  the  outline  that  it  may  be  applied  to  description  of  any  of  the  patho- 
genic fungous  organisms  which  may  be  presented  to  him  in  his  laboratory  or  field 
work.  The  use  of  such  directions  is  in  line  with  the  best  teaching  methods  in  this 
country  at  the  present  time.  The  student  is  given  the  diseased  organ  or  plant  for 
study  and  by  following  the  outline  an  acquaintance  is  obtained  not  only  with  the 
diseased  conditions  of  the  host,  but  with  the  morphologic  character  of  the  fungus  as 
well.  Some  teachers  emphasize  the  importance  of  getting  away  from  the  study  of 
systematic  details  and  concentrating  the  attention  of  the  members  of  the  class  in 
mycology  upon  the  plant  diseases  on  the  basis  of  the  pathologic  phenomena  exhibited. 
Perhaps  this  is  the  best  plan  with  advanced  students,  who  have  some  knowledge 
of  the  morphology  and  classification  of  the  fungi,  a  knowledge  which  should  precede, 
it  seems  to  the  writer,  a  more  detailed  study  of  these  interesting  plants.  It  is  recom- 
mended to  the  teacher  that  this  outline  be  used  closely  in  connection  with  the  study 
of  the  diseases  described  in  part  III  of  this  book.  The  teacher,  of  course,  is  at  liberty 
to  select  other  forms  for  study  as  the  geographic  locality  may  afford.     The  following 


640  LABORATORY   EXERCISES 

outline  is  suggestive  of  such  study,  where  the  heading  suggests  the  question  which 
the  students  ask  themselves  in  their  examination  of  the  diseased  plants. 
Serial  number  of  type.  Place  of  collection. 

Habitat  and  soil  condition.  Date. 

Name  of  host.  Common  names  of  disease. 

History  and  geographic  distribution. 
Additional  data  (Here  may  be  given  the  nature  and  amount  of  loss). 

SYifPTOMS 

Under  this  head  should  be  described  the  general  structural  changes  (morphologic, 
or  histologic)  which  are  manifest  in  the  diseased  host  plant,  and  which  distinguish  it 
from  a  healthy  individual.     They  may  be  treated  under  the  following  captions: 

1.  General  appearance  of  the  diseased  plant. 

2.  Change  in  form  of  part  diseased. 

3.  Change  in  taste  and  odor. 

4.  Change  in  color  as  contrasted  with  healthy  part. 

(a)  Pallor  (chlorosis),  yellow  or  white  instead  of  normal  green.     (Do  such 
names  as  mosaic,  calico  and  yellows  apply?) 

(b)  Colored  spots  or  areas  on  leaves,  stems,  fruits  (black,  brown,   orange, 
red,  variegated,  white,  yellow,  etc.). 

5.  Perforation  of  leaves  (shot-hole). 

6.  Damping-off,  wilt,  wilting,  blight  (blossom-blight,  body-blight,  leaf-blight, 
twig-blight). 

7.  Death  of  leaves,  twigs,  stems,  etc.  (necrosis).  * 

8.  Dwarfing  or  atrophy.  Several  names  have  come  into  current  use  expressive 
of  such  condition,  as:  curly  dwarf,  leaf-roll,  little-peach,  spindling-sprouts. 

9.  Increase  in  size:  hypertrophy.  Measurements  should  be  made  of  the  en- 
larged parts  as  contrasted  with  the  normal  and  the  following  names  may  be  found 
applicable  in  the  study  of  the  hypertrophy:  crown-gall,  root-gall,  root-knot,  root- 
tubercle. 

10.  Replacement  of  parts  by  new  parts. 

11.  Mummification,  character  of. 

12.  Change  in  position  of  organs. 

13.  Disappearance  or  non-formation  of  plant  parts. 

14.  Excrescences  and  malformations.'  The  following  names  may  be  found 
suggestive  in  the  description  of  excrescences  and  malformations:  Cankers,  corky 
outgrowths,  pustules,  rosettes,  scabs  and  witches'  brooms. 

15.  Exudations. 

Slime  flux. 
Gummosis. 
Resinosis. 

16.  Rotting.^ — The  following  terms  are  suggestive  of  some  kinds  of  rot:  bud-rot, 
collar-rot,  crown-rot,  foot-rot,  heart-rot,  root-rot,  stem-rot  and  the  following  par- 
ticular kinds  given  prominence  here. 


LABORATORY    AND    TEACHING   METHODS  64T 

Dry-rot. 

Soft-rot  (Gangrene). 

Black-rot. 

White-rot. 


The  incidental  or  experimental  evidence  of  disease  is  indicated  by  marks  or 
signs.  Such  signs  are  usually  afforded  by  the  fruiting  or  vegetative  part  of  the 
pathogenic  organism.  Such  terms  as  mildew,  mould,  ooze,  rust  and  smut  are  indica- 
tive of  diseased  or  parasitic  conditions. 

General  Suggestions. — In  the  report  which  is  made  by  each  student  following 
the  above  outline,  drawings  should,  as  far  as  possible,  accompany  the  descriptions. 

ETIOLOGY 

Common  Name  of  Pathogen. 

Scientific  Name. 

Family. 

Pathogenicity. 

Additonal  Data. 

Cultural  Character  of  Organism. 

Note. — In  case  the  pathogenic  organism  is  bacterial  the  directions  for  its 
study  have  already  been  given  as  recommended  by  the  Society  of  American  Bac- 
teriologists. As  the  outline  of  the  Society  is  the  outcome  of  years  of  study,  it 
should  be  followed  in  all  cases,  but  in  addition  the  following  directions  for  the  study 
of  parasitic  plant  organisms  should  be  kept  in  view  by  the  mycologic  student. 

Isolation  of  organism  in  pure  culture.  Directions  have  been  given  for  the  manu- 
facture of  culture  media  and  for  the  isolation  of  fungi  in  pure  culture.  These  should 
be  followed. 

Inoculation  of  pure  culture  into  healthy  host  plants. 

Recovery  of  organism  in  pure   culture. 

life  history 

The  Primary  Cycle. — Nature  of  mycelium  (septate,  or  unseptate;  presence  or 
absence  of  haustoria  (nature);  intercellular,  or  intracellular  hyphae;  color;  contents; 
penetration  and  destruction  of  host  cells  =  pathogenic  histology  of  host). 

Kinds  of  spores  (sexual  or  non-sexual;  conidia;  pycnospores;  oidiospores; 
chlamydospores;  ascospores;  zygospores;  oospores;  urediniospores;  teliospores; 
aeciospores;  basidiospores,  etc.). 

Sizes,  shapes  and  color  of  spores. 
Importance  in  life  cycle. 
Pathogenesis  of  primary  stage. 
Saprogenesis. 

The  Secondary  Cycles. — The  same  order  of  procedure  should  be  observed  in  the 
study-  of  the  secondary  cycles  as  in  the  examination  of  the  primary. 
41 


642  LABORATORY   EXERCISES 

Influence  of  Soil  Factors. 
Influence  of  Climatic  Factors. 
Control. 

Quaranlinc  measures. 
Spraying. 

Remedial  measures  (dressing  wounds  and  soil  amelioration). 
Breeding  (selection  of  resistant  strains  and  crossing). 
Eradication  (burning  of  diseased  plants,  cultivation  of  soil  by  rotation; 
disinfection). 

Literature  Relating  to  Disease  and  Organism. — The  citations  which  are 
given  in  this  section  can  be  arranged  with  reference  to  their  importance  and  with 
some  view  of  the  above  outline  of  study.  For  example,  papers  dealing  with  the 
disease  in  general,  with  the  morphology  of  the  fungus,  with  the  method  of  control, 
might  be  listed  separately  under  one  of  the  above  heads.  It  is  important  for  the 
student  to  get  acquainted  with  the  literature  of  a  subject;  otherwise  he  cannot 
appreciate  what  has  been  done  in  his  particular  field  of  scientific  endeavor. 
A  bibliography  should  be  made. 


\ 


CHAPTER  XXXVIII— LABORATORY  AND  TEACHING 
METHODS  (CONTINUED) 

LESSON  30 

Inoculation  Experiments. — The  experiments  recorded  below  need  not  be  rigidly 
followed  by  the  mycologic  teacher.  Other  organisms  and  other  hosts  can  be  used 
just  as  satisfactorily.  The  types  used  must  be  determined  by  locality  and  by  other 
considerations  of  cultural  methods  and  laboratory  facilities.  The  directions  below 
may  be  taken  as  samples. 

Potato  Rot{Fusariiim  trichothecoides). — Take  Green  Mountain  potato  tubers  and 
sterilize  surface  by  soaking  in  2  per  cent,  formalin  for  two  hours.  The  tubers  are 
then  held  with  towels  that  have  been  boiled  in  water,  and  are  wrapped  in  these  steri- 
lized wet  towels  after  having  been  inoculated  with  Fusarium  trichothecoides  by 
pricking  the  surface  of  the  tubers  and  dipping  them  in  distilled  water  which  holds  ^ 
the  spores  of  the  fungus  in  suspension.  The  potato  tubers  wrapped  with  wet  towels 
are  then  surrounded  with  oiled  paper  and  kept  at  a  temperature  not  lower  than 
10°  to  1 2°C.  Tubers  of  several  varieties  can  be  used,  such  as  Up-to-date,  Early  Rose, 
Irish  Cobbler.  If  the  inoculation  has  been  successful,  results  will  be  noted  in  ten 
to  fifteen  days.  A  transfer  to  potato  slant  test-tubes  will  result  in  a  fungus  which 
has  powdery-rosy  appearance.  Consult  Jamison,  C.  O.,  and  Wollenweber, 
H.  W.:  An  External  Dry-rot  of  Potato  Tubers  caused  by  Fusarium  trichothecoides. 
Journal  of  th&  Washington  Academy  of  Science,  II,  No.  6,  March  19,  191 2. 

After  the  normal  lesions  have  been  obtained  and  the  fungus  studied  mor- 
phologically under  the  microscope,  take  small  slices  of  potato  tuber  showing  healthy 
and  diseased  tissues  in  proximity  and  fix  in  chromacetic  acid.  Wash  ofi  the  fixa- 
tive in  running  water,  and  carry  through  the  alcohol,  etc.,  to  paraffin.  After  im- 
bedding in  paraffin,  section  and  mount  as  usual  (see  Lesson  42). 

Crown-gall  {Pscudomonas  tumefaciens)  (Fig.  227). — Inoculate  the  stem  of  a 
geranium  (Pelargonium  zonale)  with  the  organism  in  pure  culture  by  first 
washing  the  stem  at  the  intended  point  of  infection  with  i  per  cent,  formalin  and 
then  with  distilled  water.  Place  some  of  the  pure  culture  on  the  stem  by  means  of 
a  platinum  needle  and  prick  the  organism  into  the  stem  with  a  sterile  needle  mounted 
in  a  wooden  handle.  The  part  of  the  geranium  stem  selected  should  be  a  young 
actively  growing  leader  (consult  the  Bulletin  of  Erwin  F.  Smith,  and  the  book 
of  DuGGAR,  Diseases  of  Plants,  pp.  114-118). 

This  organism  can  be  successfull}^  grown  on  beef  agar  which  is  made  as  follows. 
To  1000  c.c.  of  peptonized  beef  bouillon  add  i  per  cent,  of  agar  flour,  steam  three- 
quarters  of  an  hour  and  cool  down  below  6o°C.  Then  add  neutralized  white  of  two 
eggs  to  clarify.  Made  to  -f  15  Fuller's  scale  by  adding  4NaOH.  The  test-tubes 
are  autoclaved  fifteen  minutes  at  iro°C. 

643 


644 


LABORATOEY    EXERCISES 


For  this  and  other  experiments  consult  Melhus,  T.  E.:  Culture  of  Parasitic 
Fungi  on  Living  Hosts.     Phytopathology,  ii:  197-203,  October,  1912. 

Pear  Blight  (Bacillus  amylovoriis,  Burrill)  (Fig.  228). — Take  some  pear  twigs 
long  enough  to  be  accommodated  easily  under  an  ordinary  bell  jar.  Cut  off 
these  stems  under  water  and  transfer  to  a  jar  under  water,  so  that  the  cut  ends  are 
not  exposed  to  the  air.  Then  make  slanting  cuts  at  the  upper  end  of  the  twigs 
with  a  sterile  knife  and  inoculate  the  cut  ends  with  the  organism.  Cover  the  twigs 
and  jar  in  which  they  are  placed  with  a  bell  jar,  as  shown  in  the  accompanying 


Fig. 


227. — Crown  gall  artificially  produced  in  greenhouse  of  University  of  Penn- 
by  inoculation  of  Pelargonium  zonule  with  Pseudononas  tumefaciens.      {Photo 


syl 

by  Charles  S.  Palmer.) 


illustration.  Note  the  result  of  the  inoculation  on  the  tissue  of  the  twigs  and  on  the 
health  of  the  leaves.  Consult  Duggar,  B.  M.:  Fungous  Diseases  of  Plants,  pp. 
121-129. 

Lettuce  Drop  (Sclerotinia  Libertiana,  Fuckel.).— Lettuce  leaves  may  be  in- 
oculated by  means  of  the  sclerotia  of  fungus,'  or  by  the  mycelium  laid  upon  the  sur- 
face of  scarified  areas  of  the  leaf.  As  inoculation  produces  a  virulent  form  of  the 
disease  control,  plantsof  lettuce  should  be  kept  for  comparison  (Duggar,  pp.  190-200). 

Wilt  of  Sweet  Corn  {Bacterium  {Pseudomonas)  Stewarti  E.  F.  Sm.  (Fig.  229). — • 
This  organism  was  furnished  on  beef  agar  and  is  best  inoculated  by  applying  small 


LABORATORY  AND  TEACHING  METHODS 


645 


quantities  of  a  pure  culture  to  a  stem  of  young  sweet  corn  and  then  pricking  it  in  by 
means  of  a  sterile  needle.  Some  have  inoculated  the  young  sweet  corn  plants 
by  placing  the  organism  in  the  drops  of  water  which  exude  from  the  tips  of  the  corn 
leaves  early  in  the  morning,  but  the  inoculation  by  means  of  needle  pricks  is  more 
certain.  Sections  should  be  made  of  the  stem  at  various  stages  of  growth  after 
inoculation.  This  is  done  by  using  a  number  of  plants.  Free-hand  sections,  or 
paraffin  sections,  will  show  the  presence  of  the  organism  in  the  vascular  bundles. 
Stain  with  carbol  fuchsin  (Duggar,  pp.  111-113). 


J^ 


W 


Fig.   228. — Arrangement  of  experiment  for  inoculation  of  pear  twigs  with  blight 
organism,  Bacillus  amylovorus. 


LESSON  31 

Black-rot  of  Cruciferous  Planls  {Bacterium  (Pseudomonas)  campesiris,  Pammel)  (see 
Smith,  Erw.  F.:  Bacteria  in  Relation  to  Plant  Diseases,  pp.  300-334;  Duggar, 
B.  M.:  pp.  107-111). — This  organism  is  best  inoculated  into  the  stem  of  young 
cabbage  plants  below  the  upper  last  three  leaves,  because  of  the  tendency  of  these 
leaves  to  drop  off  before  the  disease  has  progressed  to  its  fullest  extent.  The  stem 
is  first  washed,  the  organism  is  smeared  on  at  the  point  of  inoculation  and  pricked 
by  a  sterile  cambric  needle  into  place.  It  is  recommended  that  several  sections 
be  made,  and  that  to  secure  the  several  stages,  a  number  of  different  inoculations 
be  made. 


646 


LABORATORY   EXERCISES 


Clicstmil  Bliglit  {Endolhia  {Diaporlhe)  parasitica  (Murrill)  Anderson). — Inocula- 
tion into  the  chestnut  tree  should  be  made  into  scarifications  of  the  bark  made  by 
means  of  a  sterile  scalpel.  The  bark  should  be  washed  before  inoculation  by  means 
of  a  weak  formalin  solution  followed  by  distilled  water.  The  summer  spores  can 
be  rubbed  into  place  by  means  of  a  sterile  platinum  needle. 

AppeVs  Potato  Rot  {Bacillus  phyto- 
phthorus,  Appel.). — This  organism  read- 
ily grows  on  beef  agar.  It  is  inocu- 
lated into  washed  parts  of  the  potato 
stem  by  smearing  some  of  the  culture 
on  the  stem  and  pricking  into  place  by 
means  of  a  sterile  cambric  needle  into 
the  young  growing  tissue. 

LESSON  32 

Sleepy  Disease  of  Tomatoes  {Fusarium 
lycopersici  Sacc). — This  organism  can 
be  cultivated  on  steamed  rice,  or  on 
potato  slants.  Inoculate  just  above  the 
lower  leaves  of  the  young  stem  by  first 
washing  the  stem  with  distilled  water. 
Place  some  of  the  culture  on  the  part 
of  the  stem  to  be  inoculated  and  prick 
the  fungus  into  the  stem  with  a  sterile 
needle.  In  ten  to  fifteen  days,  the 
tomato  plants  begin  to  wilt  and  in 
three  weeks  the  diseased  conditions  are 
unusually  good  for  study.  The  culture 
growths  show  pale  orange  spore  masses 
and  a  whitish  mycelium.  The  tomato 
variety  Consate  is  not  susceptible. 
Wollenweber  used  the  variety  Stone 
and  found  it  satisfactory. 

Egg  Plant    Wilt   {Verticillium    albo- 
Young  corn  plant  showing     ^        ,       ^  1   ^     ^v      i  ^1 

th  Pseudomonas  atrum)  .—Inoculate  the  hypocotyl  near 
or  below  the  soil  level  with  spores  sus- 
pended in  water  of  a  ten  days  old  cul- 
ture.    Egg  plants  of  any  age  may  be  inoculated.     Black  sclerotia  are  found  in 
from  ten  to  fourteen  days  after  the  inoculation.     This  organism  is  readily  grown 
on  potato  slants. 

Wilt  Disease  of  the  Cotton  Cowpeas  and  Watermelon  {Neocosmospora  vasinfecta 
(Atkinson)  E.  F.  Sm.).— See  Duggar,  B.  M.:  Fungous  Diseases  of  Plants,  pp.  233- 
239;  also  Smith,  Ekw.  F.  :  Wilt  Disease  of  Cotton,  Watermelon  and  Cowpeas.  Bull. 
17,  U.  S.  Division  of  Vegetable  Physiology  and  Pathology,  1899. 

As  plants  of  cowpea,  cotton  and  watermelon  have  been  grown  in  the  greenhouse 


Fig.  '229. 
places    for  inoculation 
Stewarti. 


LABORATORY   AND   TEACHING   METHODS  647 

and  are  ready  for  inoculation,  experiments  may  be  tried  on  all  three  of  these  plants. 
Inoculation  with  this  fungus  should  be  made  into  the  roots  of  these  plants,  just  below 
the  soil  of  the  experimental  pots.  The  soil  should  be  removed  and  the  tops  of  the 
roots  laid  bare.  Inoculation  can  be  made  by  incisions  into  the  root  into  which  the 
mycelium  or  spores  of  the  fungus  are  rubbed.  After  inoculation  the  soil  can  be 
returned  to  its  place. 

LESSON  33 

Knot  of  Citrus  Trees  {S pliaropsis  tumefaciens)  .—Successiul  inoculations  have  been 
made  on  lime,  pomelo,  lemon,  tangerine  and  hardy  orange  {Citrus  trijoliata). 

First  Method.— Make  a  small  T-shaped  cut  in  the  back  of  a  lemon  or  orange  tree 
with  a  sterile  knife  and  insert  some  mycelium.  Smooth  the  bark  down  and  bind 
the  stem  with  raffia  to  cover  the  wound  completely. 

Second  Method. — Inoculate  by  pricking  the  stem  three  times  with  a  sterile  cam- 
bric needle  fixed  in  a  wooden  handle,  then  place  a  little  mycelium  over  these  punctures 
and  bind  with  raflia. 

Third  Method. — Inoculate  by  cutting  off  a  very  small  amount  (2  or  3  sq.  mm.)  of 
the  outer  bark,  then  spread  the  mycelium  over  this  injury  and  bind  it  with  irafl&a. 
A  year  may  elapse  before  the  galls  are  fully  formed. 

Consult  Hedges,  Florence,  and  Tenny,  S.  S.:  A  Knot  of  Citrus  Trees  Caused 
by  Sphaeropsis  tumefaciens.     Bull.  247,  Bureau  of  Plant  Industry,  191 2. 

Clover  Disease.- — Select  either  red,  white,  or  alsike  clover  plants  somewhere  in 
a  protected  place  in  the  garden,  or  as  potted  plants  in  the  greenhouse,  and  inoculate 
with  Bacillus  lathyri.  The  inoculation  may  be  made  by  an  atomizer.  Make  a 
suspension  of  the  organism  in  distilled  water  by  means  of  several  loopfuls  stirred  in 
the  water.  Spray  the  clover  plants  with  the  water  and  cover  with  a  bell  jar  for  a 
few  days  (J.  J.  Taubenhaus). 

LESSON  34 

Sweet  Pea  Diseases  (J.  J.  Taubenhaus). — Take  several  potted  sweet  pea  plants 
and  spray  the  leaves  by  means  of  an  atomizer,  which  has  been  sterilized  previously 
by  boiling  in  water.  Make  a  suspension  of  the  spores  of  Glomerella  rufomaculans 
in  water  and  spray  this  water  upon  the  sweet  pea  plants  which  should  then  be 
covered  with  a  bell  jar.  Study  the  stages  of  spore  germination  and  spore  inoculation 
by  sacrificing  daily  one  of  the  sprayed  plants. 

Inoculate  the  seeds  of  sweet  pea  varieties  with  cultures  of  Fusarimn  sp.  and 
Corticium  vagum  by  immersing  the  seeds  in  water  containing  a  suspension  of  fungous 
spores.  To  get  this  suspension  stir  up  the  separate  cultures  in  a  sterile  watch  glass 
in  distilled  water.  Then  dip  the  seeds  in  this  water  and  plant  the  seeds  in  loamy 
soil  in  pots  for  greenhouse  culture.  Follow  the  germination  of  the  peas  and  the 
progress  of  the  disease,  thus  communicated  to  the  plants. 

Inoculate  the  sweet  pea  by  placing  a  pure  culture  of  root-rot,  Thielavia  basicola 
on  the  roots  of  sweet  pea  plants.  Another  method  adapted  to  prove  the  patho- 
genicity of  the  fungus  is  to  sow  pure  cultures  of  it  on  sterilized  seeds  (seeds  treated 
with  5  per  cent,  formalin  for  one-half  hour)  in  sterile  pots  and  soils. 

Inoculate  seedlings  of  sweet  pea  with  Chcetomium  crispatum  by  soaking  the  seeds 


648  LABORATORY   EXERCISES 

in  distilled  water  containing  the  spores  of  the  fungus.  The  seeds  should  be  pre- 
viously sterilized,  as  described  above,  and  the  suspension  of  spores  made  as  above 
directed.  Healthy  plants  should  be  raised  from  uninoculated  seeds  as  checks  on 
the  progress  of  the  disease  in  inoculated  plants. 

Inoculate  sweet  pea  plants  with  Sclerotinia  libertiana  by  introducing  pieces  of 
the  fungus  into  pots  in  which  sweet  peas  are  growing.  Have  a  potted  plant  as  a 
check  and  cover  both  plants  with  a  bell  jar  in  order  to  imitate  the  moisture  condi- 
tions of  the  greenhouse.  After  four  to  si.x  days,  wilting  of  the  inoculated  plants 
will  be  noted,  while  the  check  remains  in  a  perfectly  healthy  state. 


LESSON  35 

Experiments  with  Artificial  Wounding  of  Plants. 

1.  Take  any  herbaceous  plant  such  as  hyacinth,  snowflake,  daffodil,  and  by 
means  of  a  pair  of  scissors  make  a  short  cut  into  the  tissues  of  the  leaves  of  these 
plants,  into  enough  of  leaves,  so  that  a  serial  study  can  be  made  of  the  formation 
of  healing  tissue.  Pieces  of  the  leaf  are  taken  from  time  to  time  and  sectioned  by 
any  of  the  methods  described  in  Lesson  42. 

2.  Take  any  living  shrub  or  tree  and  make  the  following  cuts: 

(a)  With  a  knife  cut  out  a  thin  longitudinal  piece  of  bark  down  to  the  cambium. 
{b)   Make  an  irregular  tear  in  the  bark  by  removing  a  small  piece  down  to  the 
wood. 

(c)  Cut  out  a  ring  of  bark  half  way  around  the  stem. 

(d)  Make  incisions  into  a  pine  tree  and  by  means  of  sections  study  the  flow  of 
resin  and  the  healing  operation. 

(p)  Make  incisions  into  the  ordinary  rubber  plant  Ficus  elastica,  and  study 
with  sections  the  effect  of  the  injury  on  the  cells  affected. 

(/)  Make  incisions  into  any  of  the  woody  euphorbiaceous  plants  of  the  greenhouse 
and  study  the  injuries  produced  in  a  similar  analytic  manner. 

3.  Cut  out  larger  pieces  of  bark  from  deciduous  trees  and  shrubs  and  by  sections 
study  the  formation  of  cells.  By  several  trips  to  the  fields  much  of  the  material 
illustrating  the  healing  of  wounds  can  be  obtained  for  the  making  of  sections  and  in 
all  stages  of  development  without  waiting  for  the  slow  development  of  new  tissue  in 
the  experimental  plants.     Cut  with  sliding  microtome. 

Note  the  formation  of  tyloses  in  many  of  the  woody  stems  studied.  Linden  is  an 
especially  good  tree  to  show  their  formation. 

Study  callus  formation  of  various  cuttings,  for  e.xample,  Ficus,  Geranium,  Ostrya, 
Populus,  Quercus  and  Ulrnus.  Place  the  ends  of  these  cuttings  in  different  media, 
as  follows: 

1.  One  end  in  water,  the  other  end  in  dry  air. 

2.  One  end  in  water,  the  other  end  in  moist  air. 

3.  Both  ends  in  moist  air. 

4.  Both  ends  in  water. 

5.  One  end  in  moist  air,  the  other  in  dry  air. 

6.  One  end  in  water,  the  other  in  moist  sand. 


LABORATORY    AND    TEACHING    METHODS  649 

7.  One  end  in  moist  air,  the  other  in  sand. 

8.  Two  ends  in  wet  sphagnum. 

9.  One  end  in  wet  sphagnum,  the  other  in  moist  air. 

10.  One  end  in  wet  sphagnum,  the  other  in  wet  sand,  etc. 

Try  wounding  the  cotyledons  oiPhaseolus,  Vicia,  etc.;  also  young  seedling  plants. 
Use  plaster  casts  to  envelope  the  cut  ends.  Cf.  Tittman:  Physiologische  Unter- 
suchungen  uber  Callusbildung  an  stecklinger  holziger_  Gewachse.  Pringsheim 
Jahrb.  fur  wissensch.  Bot.,  xxvii:  164,  1895. 

After  securing  callus  under  experimental  treatment,  then  cut,  stain  and  mount  for 
microscopic  study.  See  Kuster,  Ernst:,  Pathologische  Pflanzenanatomie,  2d. 
Edition. 

LESSON  36 

Gas  Injuries. — See  Exper.  Sta.  Rec,  xxx,  131,  February,  1914. 

Take  a  series  of  potted  plants  and  introduce  into  the  soil  by  means  of  the  hole, 
in  the  pot  bottom  different  quantities  of  illuminating  gas  by  means  of  a  rubber  tube 
connected  with  the  gas  pipe.  Note  the  effect  of  the  illuminating  gas  on  the  health 
of  the  plants.  Set  willow  cuttings  in  water  treated  and  untreated  with  gas;  note 
the  effect. 

Take  another  set  of  potted  plants  and  place  them  beneath  bell  jars,  as  follows: 

Plant  A  beneath  a  bell  jar  with  a  beaker  of  water  containing  illuminating  gas 
introduced  into  the  water  from  the  gas  pipe. 

Plant  B  beneath  a  bell  jar  into  which  free  gas  is  conducted  by  a  rubber  pipe  from 
the  gas  jet.  Cf.  Stone,  G.  E.:  Effects  of  Illuminating  Gas  on  Vegetation.  25th 
Annual  Report  Mass.  Agric.  Exper.  Sta.,  1913:  13-28;  The  Effect  on  Plant  Growth 
of  Saturating  a  Soil  with  Carbon  Dioxide.     Science,  new  sec.  xl:  792,  Nov.  27,  1914. 

Smoke  Injuries. — See  Clevenger,  J.  F. :  Mellon  Instit.  Bull.  No.  7. 

Take  a  series  of  potted  plants  of  different  species  and  expose  them  to  smoke 
conducted  to  them  by  means  of  glass  tubes  or  rubber  tubes  from  the  receptacle 
where  the  smoke  is  generated.     Study  sections  of  the  smoke-injured  tissues. 

Tobacco  smoke  may  be  tried  on  tender  plants  likewise.  Consult  Bakke,  A.  L. : 
The  Effect  of  Smoke  and  Gases  on  Vegetation.  Iowa  Academy  Sciences,  1913 
(xx):  169-188. 

As  to  smoke  injuries,  consult  also  Bakke,  A.  L.:  The  Effect  of  City  Smoke  on 
Vegetation.  Bull.  145,  Agric.  Exper.  Sta.  Iowa  State  Coll.  of  Agric.  and  Mech.  Arts, 
October,  1913.  See  also  Knight,  H.  I.  and  Crocker,  Wm.:  Smoke  and  Gas  Poison- 
ing.    Bot.  Gaz.,  May,  1913:  337-371- 

Acid  Injuries. — Treat  plants  with  dilute  solutions  of  various  acids  and  note 
their  effect  on  the  leaves  and  flowers.  The  common  morning  glories,  Ipomcea 
purpurea,  are  useful  for  this  purpose. 

Raise  some  morning-glory  plants  to  flower  and  treat  with  dilute  acids  by  spray- 
ing with  an  atomizer.  Cf.  Stone,  George  E.:  The  Influence  of  Various  Light 
Intensities  and  Soil  Moisture  on  the  Growth  of  Cucumbers  and  their  Susceptibility 
to  Burning  from  Hydrocyanic  Acid  Gas.  25th  Annual  Report.  Mass.  Agric.  Exper. 
Sta.,  1913:  29-40. 


650  LABORATORY   EXERCISES 

LESSON  37 

Enzyme  Diseases. — Study  these  diseases  of  green  plants  by  taking  a  series  of 
leaves  of  various  variegated  Anthuriums  and  other  greenhouse  species  and  treat 
them  as  follows:  The  leaves  to  be  tested  are  to  be  boiled  for  about  one  minute  in 
water,  when  they  should  be  flaccid  and  free  from  intercellular  air.  They  are  then 
placed  in  methylated  spirit  warmed  to  50°  to  6o°C. :  cold  spirit  will  remove  the  chloro- 
phyll, but  not  so  quickly.  To  produce  the  iodine  reaction,  place  the  decolorized 
leaves  in  alcoholic  tincture  of  iodine,  dilute  with  water  to  the  color  of  dark  beer. 
In  a  few  minutes  they  will  be  stained,  and  after  washing  in  fresh  water,  they  should 
be  spread  out  on  a  white  plate  so  that  their  tint  may  be  well  seen.  When  full  of 
starch  they  are  almost  black,  and  with  less  amount  of  starch,  the  color  sinks  through 
purple,  gray  and  greenish-gray  to  the  yellow  tint  of  starchless  leaves  (Sach's  method). 

In  Schimper's  method  prepare  strong  chloral  hydrate  by  dissolving  the  crystals 
in  as  much  distilled  water  as  will  just  cover  them.  The  solution  is  now  colored  by 
the  addition  of  a  little  tincture  of  iodine  and  is  ready  for  use. 

Discoloration  of  Cut  Pieces  of  Plants. — Cut  slices  of  fresh  potatoes  and  expose  them 
to  the  action  of  the  air.  Also  grate  some  of  the  material  and  test  the  rapidity  of 
discoloration. 

Take  similar  pieces  and  place  them  in  distilled  water  for  twelve  hours.  Then 
expose  the  cut  pieces  to  the  air,  and  note  the  result. 

These  same .  experiments  can  be  performed  with  various  toadstools  and  fleshy 
fungi,  when  these  are  in  season. 

Bibliography. — Allard,  H.  A.:  The  Mosaic  Disease  of  the  Tobacco.  Bull.  U.  S. 
Dept.  Agr.,  No.  40,  pp.  33,  Jan.  15,  1914- 

LoEW,  O.:  Catalase.     U.  S.  Dept.  Agr.,  Report  68. 

Stone,  Geo.  E.  :  Mosaic  and  Allied  Diseases  with  Especial  Reference  to  Tobacco 
and  Tomatoes.     25th  Annual  Report  Mass.  Agric.  Exper.  Sta.,  1913:  94-104. 

Woods,  A.  F.:  Mosaic  Disease  of  Tobacco.  U.  S.  Dept.  Agr.,  Bureau  of  Plant 
Industry,  Bull.  18. 

Chlorosis. — Grow  vetches  and  peas  in  nutrient  solution;  add  2  per  cent,  calcium 
carbonate,  when  chlorosis  immediately  appears,  even  if  iron  sulphate  is  present  in 
the  solutions.  A  few  days  in  iron  nitrate  will  cause  the  return  of  the  green  color. 
In  treating  plants  for  chlorosis,  a  0.2  per  cent,  solution  of  iron  nitrate  sprayed  on  the 
leaves  gives  good  results. 

Where  pineapples  can  be  grown  in  the  greenhouse  or  the  open  the  following  facts 
will  suggest  a  line  of  experiments  with  them  and  their  chlorosis. 

Chlorotic  pineapples  in  Hawaii. occur  on  acid  or  neutral  soils  that  average  5.0 
per  cent.  Mn304  and  0.5  per  cent.  CaO.  Chlorotic  pineapples  in  Porto  Rico  occur 
on  soils  containing  from  2  to  80  per  cent,  carbonate  of  lime  and  no  manganese. 
That  the  chlorosis  in  Porto  Rico  is  induced  by  the  carbonate  of  lime  was  proved  by 
direct  experiment.  Soils  which  normally  produced  healthy  pineapples  were  made 
to  produce  chlorotic  plants  by  the  admixture  of  carbonate  of  lime  from  different 
sources.  We  may  thus  speak  of  one  as  a  manganese-induced  chlorosis  and  the  other 
as  a  lime-induced  chlorosis.  The  lime  chlorosis  has  been  shown  to  be  due  to  a  lack 
of  iron  in  the  plant,  caused  by  the  carbonate  of  lime  diminishing  the  avaflability 


LABORATORY   AND   TEACITING   METHODS  65 1 

of  iron  in  the  soil.  M.  O.  Johnson  at  the  Hawaiian  Experiment  Station  has  shown 
that  the  chlorosis  of  pineapples  occurring  on  highly  manganiferous  soils  can  be  cured 
by  spraying  the  leaves  with  ferrous  sulphate,  similarly  in  Porto  Rico  the  disease  due 
to  calcareous  soils  can  be  cured  by  the  application  of  iron  salts.' 

LESSON  38 

Study  of  Mislldoe. — Procure  living  material  of  the  American  mistletoe  (Phora- 
dendron  flavescens)  or  European  mistletoe  {Viscum  album)  and  make  sections  with 
the  sliding  microtome  of  the  stem  of  host  and  the  parasitic  roots  of  the  parasite 
and  study  in  detail  the  association  of  host  and  parasite  (Figs.  119,  120,  121). 

This  method  of  study  can  be  used  with  Loranlhus  Sadebeckli  on  Citrus  niedica. 
See  Klebahn,  Dr.  H.:  Grundziige  der  allgemeinen  Phytopathologie,  191 2:  no. 
Cf.  TuBEUF,  C.  von:  Infektionversuche  mit  der  rotfriictigen  Mistel.  Naturw. 
Jahrb.  Forst.  und  Landw.,  xi:  51;  Bot-Centralblatt,  123:  293. 

Dodder. — Gather  material  of  Cuscuta,  Orohanche,  Gerardia,  Lathraa  and  other 
parasites,  and  study  their  anatomy  as  connected  with  the  anatomy  of  the  hosts  on 
which  they  occur  (Figs.  117,  122,  123). 

The  writer  has  frequently  made  sections  of  the  stems  of  the  Jo-Pye  weed,  Eupa- 
torimn  purpureum,  parasitized  by  Cuscuta  Gronovii.  These  sections  were  made  with 
the  sliding  microtome  and  have  been  kept  in  50  per  cent,  alcohol  until  ready  for  use. 
As  class  exercises  they  have  been  double-stained  with  safranin  and  methyl  green, 
which  brings  out  the  relationship  of  host  and  parasite  very  nicely.  Finally  the 
sections  have  been  mounted  in  balsam  and  drawn  by  each  member  of  the  class. 

LESSON  39 

Wire  Worms  in  Plants. — As  the  subject  of  the  injurious  effects  of  animals  on 
plants  is  a  large  one  and  belongs  rather  to  entomology  and  other  departments  of 
Zoology  only  one  case  will  be  studied  here. 

Nematode  Infection  of  Plants.- — Secure  material  showing  the  root  infection  of 
horticultural  plants  by  the  nematode  worm,  Heterodera  radiciccla.  Make  sections 
showing  relation  of  parasite  to  host. 

Take  healthy  plants  and  infect  them  by  transplanting  into  a  soil  containing  the 
eggs  or  the  live  round  worm.  Study  entry  of  the  parasite  into  the  hosts  and  by 
paraffin,  celloidin  or  sliding  microtome  sections,  study  the  relation  of  the  parasite 
and  host  plants. 

Similarly,  a  study  of  insect  galls  can  be  made  and  their  anatomy  studied  accord- 
ing to  the  description  of  galls  previously  given  in  the  second  part  of  this  book. 
Such  a  study  of  galls  should  be  encouraged  by  the  teacher,  wherever  time  and  the 
arrangement  of  the  courses  makes  it  practicable  to  do  so. 

^  GiLE,  P.  L.:  Chlorosis  of  Pineapples  Induced  by  Manganese  and  Carbonate 
of  Lime.  Science,  new  ser.,  44:  856,  Dec.  15,  1916.  Maze,  P.,  Ruot,  M.  and 
Lkmoigne,  M.:  Calcareous  Chlorosis  of  Green  Plants:  The  Role  of  Root  Excretions 
in  the  Absorption  of  Iron  in  Calcareous  Soils.  Compt.  Rend.  Acad.  Sci.  (Paris), 
157  (1913),  No.  12,  pp.  495-498  (Exper.  Sta.  Rec.  xxix:  826). 


652  LABORATORY    EXERCISES 

LESSON  40 

Relation  of  Light  to  Pathologic  Conditions. — While  light  plays  an  important  part 
in  the  development  of  normal  tissue,  a  lack  of  it  is  responsible  for  man}'  abnormal 
conditions,  and  there  are  a  number  of  diseases  common  to  plants  under  glass  which 
are  traceable  to  insufficient  light.  Plants,  such  as  cucumber,  grown  under  the  poor 
light  common  to  November  and  December,  have  leaves  of  poor  color,  slender  and 
elongated  petioles,  and  little  mechanic  or  resistant  tissue,  and  when  subjected  to  the 
bright  sun  in  the  early  spring  every  plant  in  the  house  will  wilt.  Poor  light  also 
renders  cucumber  plants  more  susceptible  to  powdery  mildew  and  often  causes  the 
tender  edges  of  the  leaves  to  wilt,  turn  brown  and  die.  The  larger  number  of  leaves 
produced  in  lettuce  plants  prevent  light  from  reaching  the  stem,  and  stem-rot  (Sclero- 
tinia)  or  "drop"  could  undoubtedly  be  prevented,  if  the  stem  were  continually 
exposed  to  sunlight.  The  leaf  blights  of  chrysanthemum  and  tomato,  caused  by 
Cylindrosporium,  are  associated  with  insufficient  light  and  circulation  of  air  at  the 
base  of  the  stem.  Cf.  Stone,  George  E.:  The  Relation  of  Light  to  Greenhouse- 
Culture.     Bull.  144  (July,  1913),  Mass.  Agric.  Exper.  Sta. 

Experimental  Work. — Grow  cucumbers  and  lettuce  plants  from  seed  and  expose 
the  potted  plants  to  various  light  intensities  in  the  greenhouse  by  shading  with 
several  thicknesses  of  glass,  by  placing  in  shaded  places  in  the  greenhouse,  by  growing 
next  to  the  glass  in  the  best  lighted  places.  Note  the  effect  on  the  growth  and  general 
health  of  the  plants.     Grow  morning  glories  in  pots  during  winter  and  study  growth. 

Etiolation  and  the  Health  or  Vigor  of  Plants. — In  order  to  study  the  tonic  influence 
of  light  upon  a  plant,  we  must  study  its  growth  in  darkness.  We  find  that  a  plant 
grown  in  the  dark  is  modified  both  in  form  and  structure.  The  woody  and  scleren- 
chymatous  elements  are  much  reduced,  and  the  parenchyma  of  the  cortex  is  in- 
creased in  bulk.  The  stem  becomes  very  much  elongated  and  remains  slender. 
It  is  more  succulent  than  a  normal  stem,  and  bears  extremely  small  leaves  which  grow 
out  from  it  at  a  more  acute  angle  than  those  which  rise  upon  a  normally  illuminated 
stem.  The  reaction  of  its  sap  is  much  more  acid.  The  chloroplasts  do  not  become 
green,  the  pigment,  which  they  contain,  known  as  etiolin,  being  a  pale  yellow.  In 
the  leaves,  the  differentiation  of  the  mesophyll  into  palisade  and  spongy  parenchyma 
does  not  take  place.     Plants  thus  affected  by  darkness  are  said  to  be  etiolated. 

Experimental  Work. — Grow  the  following  plants  in  light  and  in  total  darkness: 
Arisama  triphyllum,  Asparagus  officinalis,  Caladium  esculcntum,  Castanea  dentata, 
Aesculus  hippocastanum,  Hyacinthus,  Onoclea  sensibilis,  Osmunda  cimtaniomea, 
Polystichum  acrostichoides,  Quercus  rubra,  Sarracenia  purpurea,  etc.  Contrast 
influence  of  etiolation  by  a  determination  of  water  content,  dried  material,  ash, 
starch  (by  iodine  method)  duration  of  etiolated  organs  and  plants,  structure  of  leaves, 
development  of  emergences,  stomata,  lenticels,  collenchyma,  schlerenchymatous 
and  other  histologic  structures.  Sections  can  be  made  by  paraffin  and  celloidin 
methods,  etc. 

LESSON  41 

Withering,  or  Wilting  of  Plants. — When  the  amount  of  water  given  off  by  plants 
in  transpiration  is  excessive,  the  leaves  and  branches  lose  their  turgescence,  become 


LABORATORY   AND    TEACHING   METHODS  653 

flaccid  and  droop,  in  other  words  they  wilt,  or  wither.  This  withering  may  be  due 
to  the  lacli  of  water  in  sufficient  quantities,  in  the  soil,  or  it  may  be  due  to  the  pres- 
ence of  salts  of  high  osmotic  equivalent  in  the  soil,  which  render  the  absorption  of 
water  difficult,  or  impossible.     Plasmolysis  may  induce  wilting. 

Experimental  Study. — Take  two  potted  plants  and  wrap  the  pot  in  rubber  dam, 
or  oiled  paper,  so  as  to  cover  the  pot  and  soil  to  prevent  evaporation  from  their 
surfaces.  Weigh  both  potted  plants  carefully.  Water  one  each  day  with  a  meas- 
ured quantity  of  water  and  let  the  other  remain  unwatered  until  the  plant  begins  to 
wilt,  then  weigh  it  carefully  to  determine  the  amount  of  available  water  transpired. 
Then  knock  out  the  plant  and  weigh  the  soil  after  drying  in  an  oven  to  determine 
the  amount  of  hygroscopic  water  present. 

We  now  make  the  following  very  instructive  experiment  with  Hdianthus  tuhero- 
SKS.  We  bend  down  a  long  shoot  without  separating  it  from  the  plant,  and  without 
cracking  it,  so  that  a  portion  20  cm.  from  the  summit  dips  into  water  contained  in  a 
vessel  placed  below  it,  the  summit  of  the  stem  and  the  leaves  not  being  wetted. 
We  cut  through  the  stem  with  a  sharp  knife  under  water,  so  that  the  cut  surface 
remains  under  water.  Our  shoot  keeps  fresh  for  days,  while  other  Helianthiis 
shoots  cut  off  in  the  air,  and  then  at  once  placed  in  water,  rapidly  wither.  We  may 
make  them  turgescent  again  by  placing  a  withered  shoot  in  the  shorter  limb  of  a 
U-shaped  glass  tube  containing  water  fixed  in  place  in  the  tube  by  a  rubber 
cork  fitted  air-tight  about  the  stem.  Mercury  is  now  poured  into  the  longer  limb 
of  the  tube  and  its  pressure  is  sufficient  to  revive  the  withered  shoot.  Consult 
Shive,  John  W.  and  Livingston,  B.  E.:  The  Relation  of  Wilting  Plants.  The 
Plant  World,  No.  4,  April,  1914:  81-129. 

Plasmolysis  and  Wilting. — Prepare  250  c.c.  of  0.5  gram-molecular  (M)  solutions 
of  potassium  nitrate  and  of  sodium  chlorid  as  stock  solutions.  From  these  solutions 
make  dilutions  in  small  vials,  capacity  about  25  c.c.  to  contain  the  following  strengths 
of  each  of  the  above  solutions,  namely  o.io,  0.20,  0.30,  and  0.40  molecular  (M);  also 
one  vial  with  distilled  water  as  a  control.  In  each  of  the  dilutions  place  a  seedling 
of  some  plant  (root  as  nearly  entire  as  possible)  with  delicate  stem  or  leaf  stalks, 
such  as  lettuce,  radish  or  mustard.  Water  plants  can  also  be  used,  such  as  Elodea 
gigantea,  Vallisneria  spiralis,  Trianca  bogotensis  and  the  staminal  hairs  of  Trades- 
cantea  and  the  filaments  of  Spirogyra  nilida.  Observe  the  dilutions  in  which  wilting 
occurs  and  note  the  time  required  in  the  solutions  in  which  it  occurs.  Compare 
the  equivalent  strengths  of  the  two  salts  (The  Country  Gentleman,  Dec.  6,  1913: 
1781). 


LESSON  42 

Methods  of  Sectioning. — By  the  time  that  this  lesson  is  reached  some  of  the  plants 
which  have  been  wounded  or  have  been  inoculated  with  the  various  bacterial  and 
fungous  organisms,  or  have  been  treated  in  various  ways  experimentally,  will  begin 
to  show  growth  reactions.  Such  material  can  be  studied  by  the  making  and  mount- 
ing of  sections.  The  sections  can  be  made  in  one  of  three  ways:  (i)  By  free-hand 
sectioning,  the  razor  ground  flat  on  one  side  being  held  in  the  hand;  (2)  by  the  slid- 


6S4 


LAJ30RATORY   EXERCISES 


ing  microtome  (Fig.  230);  (3)  by  the  rotary  microtome,  the  material  having  been 
imbedded  in  paraffin.     If  desirable,  the  material  to  be  cut  on  the  sliding  microtome 


can  be  prepared  by  the  celloidin  method.     Where  the  sections  to  be  made  are  of 
woody  material  they  can  be  cut  directly  on  the  sliding  microtome,  and  the  sections^ 


LABORATORY    AND    TEACHING    METHODS  655 

as  fast,  as  they  are  cut,  should  be  placed  in  50  per  cent,  alcohol.  Where  free-hand 
sections  are  used  they  should  be  placed  immediately  in  50  per  cent,  alcohol. 

Crlloidin  Method. — It  is  customary  to  use  two  solutions  of  celloidin,  a  "thick" 
and  a  "thin."  The  thick  solution  (about  10  or  12  per  cent.)  should  have  the  con- 
sistency of  thick  syrup.  The  thin  may  be  made  by  mixing  equal  parts  of  thick 
and  ether  alcohol.  The  material  inoculated  as  described  in  the  preceding  lessons  is 
fixed  in  chrom-acetic  acid  solution  prepared  as  follows. 

Chrom-acetic  Acid  Fixative. 

Chromic  acid,  i  gram 
Glacial  acetic  acid,  i  c.c. 
Water,  98  c.c. 
Fle.mming's  Fluid  (Weaker  solution). 

[  r  per  cent,  chromic  acid,  25  c.c. 

A.  {  1  per  cent,  acetic  acid,  10  c.c. 
[  Water,  55  c.c. 

B.  I  per  cent,  osmic  acid,  10  c.c. 

Keep  the  mixture  A  made  up,  and  add  B  as  the  reagent  is  needed  for  use,  since 
it  does  not  keep  well. 

Wash  the  fixed  material  carefully  in  running  water  for  several  hours  and  put  into 
30  per  cent,  alcohol,  then  by  successive  steps  into  50  per  cent.  75  per  cent.,  95  per 
cent,  and  absolute  alcohol.  After  dehydrating  in  absolute  alcohol,  the  succeeding 
steps  are  taken. 

1.  Ether  alcohol,  i  to  2  days. 

2.  Thin  celloidin,  2  to  6  days. 

3.  Thick  celloidin,  3  to  10  days. 

Use  of  Alcohols  and  Celloidin. — The  celloidin  is  dissolved  in  equal  parts  of  ether 
and  absolute  alcohol  about  i  part  by  weight  of  celloidin  to  15  parts  of  the  solvent. 
After  the  material  is  thoroughly  penetrated  by  this  solution,  it  is  passed  to  a  stronger 
solution,  containing  i  part  of  celloidin  to  11  parts  of  the  solvent  and  finally  to  a 
solution  containing  i  part  of  celloidin  to  8  parts  of  the  solvent.  After  remaining  a 
suitable  time  in  the  last  solution,  the  object  is  ready  for  imbedding.  For  this 
purpose,  a  paper  strip  may  be  wound  tightly  about  the  end  of  a  small  block  of  suit- 
able size  and  material,  so  as  to  form  the  sides  of  a  box  open  above,  with  a  bottom 
the  end  of  the  block  of  wood.  This  box  is  now  filled  with  the  thickest  celloidin 
solution,  and  in  it  the  object  is  placed  and  oriented  carefully  by  needles  wet  with  the 
ether-alcohol  mixture.  As  soon  as  a  strong  film  has  developed  over  the  surface  of 
the  celloidin,  the  whole  block  of  material  is  plunged  into  80  per  cent.  After  the 
celloidin  has  hardened  in  the  alcohol,  the  paper  ring  is  removed  and  the  mass  is 
trimmed  to  the  desired  size. 

In  cutting,  the  block  is  clamped  in  the  sliding  microtome,  where  the  knife  is  set 
obliquely,  so  that  the  celloidin  sections  may  be  cut  with  a  long  drawing  stroke. 
The  knife  and  top  of  the  block  should  be  kept  wet  with  80  per  cent,  alcohol,  and  as 
rapidly  as  the  sections  are  cut,  they  should  be  placed  in  the  alcohol  (Fig.  230). 

The  sections  are  attached  to  the  slide  by  placing  the  slide  in  a  closed  chamber 


656  LABORATORY   EXERCISES 

over  ether.  The  ether  vapor  quickly  dissolves  the  celloidin  to  cause  the  sections 
to  adhere  firmly  to  the  slide  on  removal  from  the  chamber.  After  the  removal  of 
the  celloidin,  the  sections  can  be  stained  with  appropriate  stains.  For  mounting 
in  Canada  balsam,  celloidin  sections  may  be  cleared  with  a  mixture  of  3  parts  xylol 
and  1  part  phenol. 

Paraffin  Method. — The  fixing  and  dehydrating  of  material  for  imbedding  in 
parafl&n  is  performed  in  a  manner  similar  to  that  for  work  with  celloidin  up  to  the 
dehydration  in  absolute  alcohol.  The  following  schedule  should  be  followed 
subsequently. 

Transfer  from  absolute  alcohol  to  pure  xylol,  allowing  at  least  two  hours  in  each 
of  the  following  three  mixtures,  ^i  alcohol  +  3^^  xylol;  3^2  alcohol  +  M  xylol; 
^■i  xylol  +  H  alcohol,  xylol.  Add  to  the  mixture  of  paraffin  dissolved  cold  in  xylol. 
Place  in  melted  paraffin  in  the  bath,  kept  at  55°C.,  two  to  twenty-four  hours  as 
convenient.  Imbed  in  paper  capsules,  or  in  small  shallow  glass  dishes.  Section 
with  rotary  microtome;  about  6  to  lo/i  is  a  good  thickness. 

See  Lesson  43  for  details  of  cutting  frozen  section  by  the  microtome  and  the 
method  of  freezing  each  section.     Lesson  43  may  be  introduced  here. 

Fastening  of  Sections  to  Slide. — After  cutting,  fasten  section  to  slide  by  using 
Meyer's  albumen,  or  by  the  process  of  drying  on  the  slide  after  treatment  with  tepid 
water  to  remove  the  wrinkles. 

Dissolve  off  paraffin  in  xylol. 

Pass  down  through  100  per  cent.,  95  per  cent.,  85  per  cent.,  70  per  cent.,  50  per 
cent.,  30  per  cent.,  alcohol,  thirty  seconds  each. 

Delafield's  ha?matoxylin,  fifteen  minutes. 

Rinse  in  water  five  minutes. 

Pass  up  through  30  per  cent.,  50  per  cent.,  70  per  cent.,  95  per  cent.,  and  absolute 
alcohol. 

Put  in  xylol  at  least  one  minute. 

Mount  in  balsam. 

Note. — All  of  the  material  obtained  in  the  inoculation  experiments  should  be 
studied  microscopically.  The  above  methods  of  fixing,  imbedding,  sectioning  and 
staining  are  applicable  in  all  of  this  work. 

If  time  permits,  all  of  the  organisms  inoculated  in  the  plants  should  be  recovered 
and  in  pure  culture  by  the  methods  outlined  in  Lesson  22.  Direct  inoculation  of 
media  in  plugged  test-tubes  can  be  used.  A  reinoculation  of  the  recovered  organisms 
is  desirable,  if  time  permits  the  class  to  undertake  such  additional  work. 


LESSON  43 

Freezing  of  Material  and  Cutting. — Freezing  Microtome. — The  material  may  be 
imbedded  in  a  thick  solution  of  gum  arable  which  is  frozen  on  a  metal  plate  cooled 
to  the  freezing  temperature  by  conducting  under  the  plate  a  mixture  of  ice  water 
and  salt.  This  is  accomplished  by  filling  a  glass  vessel  full  of  a  mixture  of  ice  and 
salt  and  conducting  the  water  from  the  jar  by  a  tube  (.4)  through  metal  a  box  {B) 
on  which  the  sections  are  placed  in  the  mucilage. 


LABORATORY  AND  TEACHING  METHODS 


657 


The  circulation  of  the  ice-salt  water  is  accomplished  by  allowing  it  to  drip  from 
a  small  orifice  at  the  end  of  the  glass  tube  C. 

The  block  of  frozen  mucilage  with  the  contained  substance  held  on  the  freezing 
plate  is  then  cut  with  the  hand  microtome  or  with  the  design  of  microtome  shown 
on  the  next  page. 

Or  the  material  may  be  frozen  in  the  design  of  freezing  chamber  shown  on  page 
659  and  sectioned  by  Spencer  automatic  laboratory  microtome  No.  880,  as  indicated 
in  the  accompanj-ing  figures.  If  mucilage  is  used  it  can  be  removed  by  placing  the 
sections  as  rapidly  as  cut  in  warm  water. 

CO2  Freezing  Allachmcnt. — The  freezing  device  in  this  attachment  consists  of  a 
small  metal  cylinder.     The  object  is  placed  on  the  flat  disk  top  of  the  cylinder, 


Fig.   231. — Freezing  attachment  for  use  of  CO2  in  freezing  microtome. 

which  measures  36  mm.  in  diameter,  and  is  frozen  by  the  expansion  of  the  CO2. 
This  device  is  connected  with  the  gas  cylinder  by  a  flexible  copper  tube,  provided 
with  a  connecting  nut  for  joining  to  the  cylinder  and  the  necessary  adapter  for  fitting 
to  the  microtome.  It  is  furnished  also  with  an  extra  valve,  which  can  be  placed  at 
either  end  of  the  tube. 

CO2  gas  furnishes  the  most  rapid  and  convenient  medium  for  freezing  specimens 
and  can  be  used  in  this  attachment  with  either  the  table  or  physician's  microtome 
(Figs.  231,  232).     An  ether  attachment  is  also  used  (Fig.  233). 


LESSON  44 

Use  of  Drawing  and  Projection  Apparatus. — The  author  has  found  it  an  excellent 
training  for  students  to  learn  the  use  of  the  drawing  apparatus  designed  by  Edinger, 
as  well  as  the  new  Spencer  photomicrographic  camera.     These  pieces  of  apparatus 
can  be  used  for  drawing,  for  projection  and  for  photomicrography. 
42- 


6s8 


LABORATORY   EXERCISES. 


The  Edinger  drawing  and  projection  apparatus^  (Figs.  234,  235)  projects  micro- 
scopic objects  even  under  a  high  magnification  directly  upon  the  drawing  board  so 
that  the  outline  can  be  traced  in  pencil.  The  image  thus  projected  can  be  used  for 
demonstrating  to  a  small  audience  and  also  for  photomicrography.  For  such  work 
a  powerful  illuminant  is  used  with  a  hand-fed  electric  arc  taking  4  amperes.  It  may 
be  used  with  a  suitable  plug  connected  with  the  direct-current  house  supply  (alter- 
nating current  may  be  used  by  special  arrangement).     The  crater  in  the  positive 


|_f^||t4LOCo 
Fig.  "232. — Clinic  microtome  with  freezing  attachment. 


carbon  from  which  light  emanates  is  brought  to  coincide  with  the  optic  axis  of  the 
apparatus  by  means  of  the  two  screws  (o)  as  in  Fig.  234,  and  the  lamp  with  the  con- 
densing system  K  can  be  moved  along  the  optic  axis  by  the  lever  G.  The  distance 
between  the  carbons  is  regulated  by  the  milled  head  (6)  which  if  out  of  reach  of 
the  operator  can  be  turned  by  the  long  handle  connected  to  (c).  The  smaller  car- 
bon which  is  placed  horizontally  should  not  project  into  the  optical  axis,  or  crater 
area  of  the  larger  vertical  carbon. 

The  apparatus  proper  consists  of  a  cast-iron  pillar  S,  Fig.  234,  mounted  upon  a 
1  May  be  had  of  E.  Leitz,  30  East  icSth  Street,  New  York  City. 


LABORATORY  AND  TEACHING  METHODS 


659 


rectangular  frame  into  which  a  drawing  board  is  fitted.  The  fitting  is  grooved  to 
allow  the  adjustment  of  the  illuminant  L  by  the  lever  G,  the  stage  0,  and  the  objec- 
tive holder  //,  the  face  being  graduated  to  ]^i  cm.  in  order  that  the  correct  position  of 
the  stage  O,  which  varies  according  to  the  objective  in  use  (see  Table  A),  can  be 
determined.  The  same  table  gives  the  correct  size  of  diaphragm,  five  accompanying 
each  outfit,  viz.:  12,  18,  24,  32  and  46  mm.  diameter.  The  cover-glass  faces  the  ob- 
jective when  the  slide  with  object  is  placed  in  position.  The  objective  carrier  H 
which  has  a  rack  and  pinion  for  coarse  adjustment  and  a  micrometer  screw  for  fine 
adjustment  occupies  a  constant  position  on  the  fitting  B,  viz.,  i  cm.  from  the  lower 


Fig.   233. — Ether  or  rhigoline  freezing  attachment  for  freezing  microtome. 


end,  but  can  be  removed  if  necessary.     The  fine  adjustment  can  be  controlled  by 
a  long  rod  similar  to  that  used  for  the  setting  of  the  arc. 

Above  the  stage  two  lenses  of  different  foci  are  mounted  in  a  swing-out  {K2, 
Fig.  234)  which  has  a  sliding  focussing  adjustment  and  iris  diaphragm,  and  is  so 
contrived  that  either  of  the  condensers  or  the  diaphragm  only  can  be  interposed  in 
the  optic  axis.  The  microscope  body  T  can  be  removed  from  the  fitting  M,  into  which 
it  pushes,  and  the  triple  nosepiece  is  mounted  on  a  sliding  attachment,  so  that  it  can 
be  interchanged  from  a  similar  slide  carrying  the  microsummar  lenses.  The  draw 
tube  should  always  be  set  at  152  mm.  when  working  with  the  nosepiece;  otherwise, 
at  170  mm.     Should  the  apparatus  be  required  for  projection  the  whole  optical 


66o 


LAEORATORY   EXERCISES 


system  can  be  rotated  from  the  vertical  to  the  horizontal  position  by  j)ulling  out  the 
spring  catch  E,  Fig.  234. 


Fig.   234. —  Details  of  Edinger's  drawing  apparatus.      Z,  Drawing  board;  T,  micro- 
scopic attachment;  K\  and  A'2  condensers;  L,  electric  lamp  attachment. 


For  photomicrographic  work  a  camera  is  clamped  to  the  pillar  S,  Fig.  234,  the 
plate  holder,  which  will  take  plates  of  any  size  up  to  24  by  30  cm.,  resting  on  the 


LAEORATORY    AND    TEACHING    METHODS 


66l 


drawing  board  Z  (Fig.  234).  Having  determined  the  camera  extension  required  by 
means  of  a  special  set  screw  provided,  an  allowance  of  2.8  cm.  is  made  for  the 
height  of  the  plate  above  the  drawing  board.     The  arm  clamping  the  camera  to 


Fig.   235. — Edingti  s  diawm^ 


icroscopic  drawing. 


the  pillar  is  then  raised  until  the  collar  fits  over  the  draw  tube  of  the  microscope 
body  T,  or  over  M,  when  working  with  the  niicrosummars,  thus  ensuring  a  light- 
tight  connection.     It  is  advisable  to  support  the  bellows  by  the  strap  pieces  shown  in 


662 


LABORATORY   EXERCISES 


Fig.  236,  when  extended.     Correct  focus  is  determined  by  the  observation  of  the 
image  upon  a  paper  surface  in  place  of  the  usual  ground  glass. 


Fig.  236. — Edmgcr  b  di  i\\int 


ith  altachment  for  photo-micrography. 


The  following  tables  have  been  prepared  with  the  view  of  simplifying  the  use  of 
the  apparatus  as  much  as  possible,  and  the  best  results  can  only  be  obtained  when 


LABORATORY    AND    TEALHING    MKiTlOUS 


663 


the  instructions  given  for  the  height  of  the  stage  and  lamp,  and  the  use  of  condenser 
and  diaphragm  for  each  objective,  are  strictly  adhered  to : 

Table  A 


Objective 

Height 
of  stage 

Position  of  lamp 

with  condensing 

lens  system 

Condenser        |  ^^Se^Xlir. 

Microsummar 
80  mm. 
64  mm. 

18  cm. 
18  cm. 

As  low  as             Swung-out 
possible               Swung-out 

46  mm. 
32  mm. 

.42  mm.                 15  cm. 
35  mm.                 15  cm. 
24  mm.          1       15  cm. 
Achromatic       1 

No.  I                  17  cm. 

No.  2                   15  cm. 

Low  power 
Low  power 
Low  power 
Midway 

Swung-out 
Low  power 

18  mm. 
18  mm. 
12  mm. 

12  mm. 
12  mm. 

No.  3            i       15  cm.                                          Low  power 
No.  4            ,       15  cm.       1       As  high  as            Low  power 
No.  5                   15  cm.       !         possible              High  power 
No.  6            i       15  cm.                                          High  power 

12  mm. 
12  mm. 
12  mm. 
12  mm. 

T.VBLE  B. — Magnifications 
Of  the  Microsummars  at  Definite  Distances  from  the  Drawing  Board 


Microsummar 

Distance  from 
drawing  board 

Magnification 

f 

37Scm. 

20 

24  mm.        i 

13. 5  cm. 

10 

cn.n.            1 

46 . 0  cm. 

IS 

35  mm.         j 

21.0  cm. 

8 

38.0  cm. 

10 

16. s  cm. 

S 

64  mm.         \ 

45 . 0  cm. 

8 

21. 5  cm. 

4 

f 

46 . 0  cm. 

6 

80  mm.         j 

24 . 0  cm.                             3 

664 


LABORATORY   EXERCISES 


Table  C 

Of  the  Achromatic  Objectives  with  the  Huyghenian  Eyepieces  at  250  mm.  distance 

from  the  Drawing  Board 


Eyepiece 

Objective 

0 

I 

II 

III 

I 

13 

16 

19 

26 

2 

23 

29 

35 

46 

3 

41 

SI 

62 

.  82 

4 

73 

91 

109 

146 

S 

133 

167 

200 

267 

6 

180 

230           280 

360 

If  the  distance  between  eyepiece  and  drawing  board  =  250  mm.  be  altered,  the 
magnification  of  each  combination  will  increase  or  decrease  in  proportion.  The 
distance  should  be  read  oflF  the  scale  on  the  pillar  by  the  aid  of  the  special  set  square 
supplied. 

Beside  the  Edinger  apparatus  there  are  a  good  many  styles  of  photomicro- 
graphic  cameras,  but  the  most  recent  type  is  an  instrument  known  as  the  new 
Spencer  photomicrographic  camera,  which  may  be  attached  to  the  microscope  with- 
out disturbing  the  adjustments.  It  may  be  used  on  its  tripod  in  any  position  from 
horizontal  to  vertical  which  makes  it  available  for  carrying  in  any  ordinary  pho- 
tography. This  camera  may  be  used  with  any  microscope,  or  it  may  be  removed 
from  its  support  and  used  for  hand-camera  purposes. 

LESSON  45 


TO  THE  INSTRUCTOR 

In  connection  with  the  use  of  the  Edinger  apparatus  the  following  suggestions 
as  to  drawing  may  be  apropos. 

The  experience  of  most  science  teachers  has  revealed  the  fact  that  as  a  rule 
beginners  in  attempting  to  give  an  accurate  account  of  their  own  observations  in 
writing  or  drawing  are  in  a  large  measure  helpless  for  want  of  a  definite  aim  or  an 
understanding  of  what  is  required  of  them  and  how  to  do  it. 

While  it  is  recognized  that  science  teachers  naturally  differ  in  the  method  of 
carrying  out  the  details  of  their  work,  yet  it  is  believed  that  it  will  be  helpful  to  the 
pupil — an  economy  of  his  time  and  effort — if  the  features  which  characterize 
scientific  description  and  drawing  in  general,  be  clearly  pointed  out  and  impressed 
at  the  beginning.  It  is  believed  that  the  following  suggestions  to  pupils  can  be 
indorsed  by  most  teachers  of  Biology  and  that  these  suggestions  will  aid  the  inex- 
perienced science  pupil. 


LABORATORY   AND   TEACHING   METHODS  665 

SUGGESTIONS    TO    STUDENTS 

Concerning  Notes. 

1.  The  laboratory  notes  or  descriptions  should  embody  only  such  facts  as  have 
been  gathered  from  your  own  observation  and  study  of  the  object.  Any  collateral 
notes  written  up  from  lectures  or  reading  should  not  be  mingled  with  those  of  your 
own  observation,  but  should  be  kept  distinct  and  under  separate  headings. 

2.  The  facts  observed  in  the  laboratory  or  field  may  be  gathered  first  on  "scratch 
[)aper"  as  temporary  notes  and  subsequently  be  written  on  the  note  tablet  in  per- 
manent form;  but  such  temporary  notes  should  be  promptly  written  up  and  not  be 
allowed  to  accumulate. 

3.  The  permanent  notes  or  descriptions  should  be  an  original  account  of  your 
own  observation.  The  statements  should  be  scrupulously  accurate  and  free  from 
figurative  expression  and  rhetoric  embellishment;  the  style  should  be  simple,  clear 
and  concise. 

4.  Frequent  reference  should  be  made  to  the  drawings  and  diagrams  which 
accompany  the  study  so  that  these  and  the  notes  may  be  mutually  helpful. 

5.  The  ability  to  give  a  clear  and  accurate  account  of  one's  own  observations 
and  conclusions  is  an  essential  in  scientific  work,  and  is  also  of  much  value  in  prac- 
tical life. 

Concerning  Drawings  and  Diagrams. 

1.  A  drawing  is  intended  to  show  the  size  and  shape  of  the  object,  and  the  pro- 
portions and  relations  of  its  parts.  In  case  the  drawing  is  to  be  smaller  or  larger 
than  the  object,  the  size  of  the  object  may  be  indicated  by  symbols,  as  for  example: 
"  X  ^i"  or  "  X  4,"  the  former  signifying  that  the  drawing  is  reduced  to  one-fourth 
and  the  latter  that  it  is  enlarged  to  four  times  the  actual  size  of  the  object. 

2.  A  diagram  is  intended  to  show  only  the  relation  of  the  parts  of  the  object  and 
does  not  pretend  to  represent  their  size,  shape  or  structure. 

3.  In  making  either  drawing  or  diagram,  do  not  aim  at  anything  ornamental,  or 
artistic  in  effect.  Let  your  aim  be  to  represent  clearly  and  distinctly  certain  facts 
of  your  observation. 

4.  First,  carefully  examine  the  object  and  have  definitely  in  mind  what  you  wish 
to  show  in  your  diagram  or  drawing  and  omit  everything  else. 

5.  Decide  in  advance  what  view  of  the  object  you  wish  to  represent  and  the  size 
of  your  drawing.  If  the  object  be  an  animal  or  a  plant,  represent  it  whenever 
practicable  in  its  most  natural  position. 

6.  With  a  fine-pointed  hard  pencil,  make  a  very  faint  outline  of  the  object,  step 
by  step  comparing  the  drawing  with  the  object,  and  omitting  at  first  all  details. 
See  that  the  proportions  are  correct,  revising  your  drawing,  if  necessary,  by  sub- 
stituting new  lines  and  ignoring  or  erasing  old  ones. 

7.  The  details  may  now  be  worked.  Avoid  much  shading  and  omit  it  altogether 
whenever  possible.  If  the  drawing  is  merely  an  outline  it  may  be  improved  by  trac- 
ing Its  lines,  and  the  effect  of  shading  may  be  produced  by  tracing  more  heavily 
those  lines  which  are  opposite  the  direction  of  the  light. 

8.  In  diagrams  no  shading  is  needed,  but  in  many  cases  the  use  of  flat  tints, 
produced  with  colored  pencils  or  preferably  water  colors  is  very  helpful. 


666  LABORATORY   EXERCISES 

9.  All  drawings  and  diagrams  should  be  accurately  and  intelligibly  labeled. 
Generally  it  is  also  desirable  that  the  parts  of  the  drawing,  especially  the  parts  of  a 
diagram,  be  designated  in  a  way  that  is  convenient  for  reference. 

10.  Drawings  should  be  made  either  entirely  in  ink,  or  entirely  in  pencil,  and  the 
lettering  also,  which  should  be  uniform,  not  one  style,  then  another. 

11.  Large  headings  should  be  more  especially  emphasized  by  larger  letters,  and 
the  lettering  of  the  larger  and  smaller  headings  should  be  of  the  same  style. 

12.  All  drawings  presented  to  the  teacher  for  examination  should  be  placed 
between  the  two  sides  of  a  folder  of  stiff  manila  paper. 

13.  The  grade  of  pencil  should  be  determined  by  the  kind  of  finish  or  surface  of 
the  drawing  paper,  but  in  general  for  science  work,  the  harder  grades  of  lead,  say 
from  4H  to  6H,  are  preferable. 

14.  The  name  of  the  student,  the  number  and  the  subject,  as  well  as  the  year, 
should  in  all  cases  be  placed  on  the  outside  of  the  manila  cover. 

Method  and  Materials  of  Photomicrography  (Fig.  236). — The  photographic 
plates  which  best  meet  the  requirements  in  photomicrographic  work  with  the 
Edinger  apparatus  are  Lumier  Sigma  9  by  12  cm.  plates,  or  the  ordinary  4  by  5 
plates.     Another  good  plate  is  known  to  the  trade  as  Seed  Special  27. 

Whatever  plate  is  used,  it  is  placed  in  the  plate  holder  of  the  photomicrographic 
camera  in  a  dark  room,  the  dull  side  of  the  plate  being  outermost.  The  holder  is 
then  placed  in  its  proper  position  in  the  photographic  camera.  Before  the  insertion 
of  the  holder,  however,  the  object  to  be  photographed  must  be  focussed  on  the 
ground-glass  plate  of  the  camera  until  a  sharp  image  is  obtained,  then  the  focussing 
screw  should  be  moved  a  trifle,  say  one  of  the  divisions  of  the  screw,  so  that  the 
object  is  focussed  up  a  slight  amount.  The  light  being  regulated  properly,  the 
exposure  is  made  by  withdrawing  the  shutter  of  the  plate  holder.  The  length  of 
time  to  expose  the  plate  can  be  determined  only  by  several  trials  until  the  operator 
learns  the  length  of  time  by  the  experience  thus  gained. 

The  most  satisfactory  developer  is  made  as  follows: 

Rodinol,  i  part. 
Water,  12  parts. 
Potassium  bromide,  10  drops  of  10  per  cent,  solution. 

The  advantage  of  this  developer  is  that  the  process  is  sufficiently  slow,  so  that  the 
operator  may  be  able  to  study  the  photograph,  as  it  makes  itself  evident. 

After  washing  in  water,  the  negative  is  placed  in  a  rather  strong  hyposulphite 
solution  as  a  fixing  bath.  The  advantage  of  rodinol  over  metol  is  that  the  develop- 
ment is  more  even  and  sure.  Where  the  photomicrographs  have  been  made  ob- 
scure, or  where  it  is  desirable  to  convert  them  into  outline  drawings  for  diagrammatic 
purposes  the  following  method  can  be  used. 

Draivings  on  Photographic  Prints. — All  pen-and-ink  drawings  of  photographic 
prints  must  be  made  with  water-proof  India  ink  after  which  the  photographic  part 
is  bleached  out  by  exposure  for  a  few  minutes  in  water  containing  cyanide  of  potash 
(i  :  500,  more  or  less).  The  drawings  should  be  exposed  in  this  bath  as  long  as 
necessary.     If  any  part  of  the  print  refuses  to  bleach,  it  should  be  moistened  with 


LABORATORY    AND    TEACHING    METHODS  667 

iodine-potassium  iodide  and  returned  to  the  cj'anide  bath.  It  is  then  passed  tlirough 
pure  water  and  dried  face  up  on  blotting  paper  in  a  place  free  from  dust. 

Bibliography. — For  details  the  student  is  referred  to  a  book  by  W.  H.  Walmsley, 
entitled,  The  A  B  C  of  Photomicrography.  A  Practical  Handbook  for  Beginner. 
New  York,  Tennent  and  Ward,  1902. 

Complete  details  will  be  found  in  Erw.  F.  Smith's  Bacteria  in  Relation  to  Plant 
Diseases,  Vol.  i:  130-151;  Barnard,  J.  Edwin:  Practical  Photomicrography,  1911: 
xii  -f  322,  London,  Edward  Arnold;  Hind,  H.Lloyd  and  Randles,  W.  Brough: 
Handbook  of  Photomicrography,  1913:  xii  +  292  with  44  plates.  New  York,  E.  P. 
Dutton  &  Co. 

Lesson  46 

The  course  in  mycology  will  not  be  complete  without  the  introduction  of 
field  trips  and  excursions  which  supplement  in  an  important  way  the  laboratory 
and  lecture  work,  and  which  will  show  the  student  how  mycology  touches 
practically  the  sciences  of  bacteriology,  chemistry,  engineering,  and  the  other 
technologic  sciences.  Besides  the  trips  into  the  woods  and  fields  for  various 
kinds  of  fungi  and  to  the  market  houses  to  collect  the  fungous  diseases  of  the 
food  plants  sold  there,  trips  can  be  planned  to  include  slaughter  houses,  cold 
storage  plants,  meat  extract  factories  and  dairies  where  the  cooling,  filtration, 
Pasteurization,  and  bottling  of  milk  can  be  demonstrated.  Mushroom  farms 
should  not  be  omitted,  nor  should  the  farms  where  vaccine  and  other  biologic 
products  are  made  be  overlooked.  Cheese,  butter,  oleomargarine  and  soap 
factories  should  be  included  in  the  schedule,  as  well  as  the  sugar  refineries. 
The  industrial  plants  where  yeasts  are  employed  should  be  investigated,  such 
as  bread  bakeries,  beer  breweries,  wine  and  pressed  yeast  factories.  The  estab- 
lishments where  pickles,  sour  krout  and  vinegar 'aTE^made  should  not  be  omitted. 
The  disposal  of  the  sewage  of  our  large  cities  will  pay  inspection.  The  con- 
servation of  manure  in  the  city  and  on  the  farm,  the  general  problems  of  soil 
mycology  and  the  preparation  of  silage  ought  to  be  introduced  by  the  field 
trips.  The  health  laboratories  of  our  large  cities  should  be  included  in  the 
itinerary.  These  are  only  a  few  of  the  places  that  might  be  visited  profitably 
near  such  large  cities  as  Boston,  New  York,  Philadelphia,  Baltimore,  Chicago, 
St.  Louis,  New  Orleans,  Denver,  and  San  Francisco,  and  smaller  places  where 
manufacturing  is  important. 

References 

Bergey,  D.  H.:  The  Principles  of  Hygiene,  Philadelphia,  1914. 
CouN,  H.  W.:  Bacteria,  Yeasts  and  Molds  in  the  Home,  New  York,  1903. 
Fuhrmann,  Dr.  Franz:  Vorlesungen  iiber  technische  Mykologie,  Jena,  1913. 
GiLTNER,  Ward:  Laboratory  Manual  in  General  Microbiology,  New  York,  1916. 
Kossowicz,  Dr.  Alexander:  Einfiihrung   in  die  Mykologie  der   Gebrauchs-und 

Abwasser,  Berlin,  19 13. 
Kossowicz,  Dr.  Alexander:  Einfiihrung  in  die  Agriculturmykologie,  Berlin. 


668  LABORATORY    EXERCISES 

Kossowicz,  Dr.  Alexander:  Lehrbuch  der  Chemie  Bakteriologie  und  Tech- 
nologic der  Nahrungs-und  Genussmittel,  Berlin,  1914- 

LiPMAN,  Jacob  G.:   Bacteria  in  Relation  to  Country  Life,  New  York,  1908. 

LoHNis,  Dr.  F.:  Handbuch  der  landvvirthschaftlichen  Bakteriologie,  Berlin. 

Lafar,  Dr.  Franz:  Technical  Mycology,  Landon,  1898-1910. 

Marshall,  Charles  E.:  Microbiology,  Philadelphia,  1911. 

Prescott,  Samuel  C.  and  Winslow,  Charles-Edward  A.:  Elements  of  Water 
Bacteriology,  New  York,  3  edit.,  1913. 

RosEMAN,  Milton  J.:  Preventive  Medicine  and  Hygiene,  New  York,  1914. 

Whipple,  George  C:  The  Microscopy  of  Drinking  Water,  New  York,  3  edit., 
1914. 


■        APPENDIX  I 

Perhaps  what  follows  may  be  looked  upon  by  some  teachers  as  hardly  forming 
appropriate  laboratory  exercises,  and,  therefore,  should  be  treated  as  in  the  nature 
of  appendices.  In  agricultural  and  horticultural  schools,  the  manufacture  and 
use  of  fungicides  and  sprays  may  very  well  form  a  part  of  the  curriculum  designed 
for  laboratory,  and  especially  for  field  purposes,  where  in  the  experimental  farm,  or 
garden,  the  spraying  apparatus  and  its  construction  can  well  be  experimented  with 
as  a  regular  part  of  the  instruction.     Hence  the  making  of  sprays  is  given  prominence. 

Fungicides. — Definition  of  Terms. — Fungicides  are  substances  which  are  capa- 
ble of  destroying,  or  preventing,  the  growth  of  spores,  or  the  mycelia  of  fungi.  Germi- 
cides are  those  substances  used  for  a  similar  purpose  with  germs,  or  bacteria.  Such 
materials  may  be  used  as  a  spray,  in  the  form  of  a  powder  dusted  on  the  plant,  or  in 
the  form  of  a  steep  into  which  the  plant,  or  plant  part,  is  dipped.  A  substance  to 
be  useful  as  a  fungicide  must  not  only  not  injure  the  plant,  but  must  at  the  same 
time  destroy'  or  hold  in  check  the  parasite.  Usually  the  material  is  most  effective 
when  the  fungous  parasites  can  be  reached  directly  by  the  spray.  If  the  fungus 
works  internally,  as  the  chestnut  blight  fungus,  such  fungicides  usually  do  harm  to  the 
host  without  touching  the  parasite  and  are,  therefore,  ineffectual. 

The  chemic  substances  used  are  naturally  of  a  poisonous  character  and  should 
be  used  with  precautions  taken  to  prevent  their  injurious  effects  upon  human  beings. 
.\n  up-to-date  agriculturist,  horticulturist,  or  orchardist  considers  the  use  of 
fungicides,  germicides,  or  insecticides,  as  essential,  as  any  of  the  other  major  opera-, 
tions  on  the  farm. 

For  convenience  of  treatment  and  ease  of  reference  the  following  fungicides  and 
insecticides  are  arranged  alphabetically.  The  formulae  have  been  taken  from  a  num- 
ber of  reliable  sources  and  they  may  be  considered  as  dependable  in  ordinary  work. 

Ammoniacal  Copper  Carbonate. — This  is  not  as  good  for  general  purposes  as 
Bordeaux  mixture.  It  is  used  instead  of  Bordeaux  when  it  is  desirable  to  avoid  the 
spotting  of  leaves  or  fruit.     It  is  prepared  as  follows: 

Copper  carbonate,  5  ounces. 

Strong  ammonia  (26°  Baume),  2  to  3  pints. 

Water  to  make  50  gallons. 

Dilute  the  ammonia  with  about  2  gallons  of  water,  as  it  has  been  found  that 
ammonia  diluted  seven  or  eight  times  is  a  greater  solvent  for  copper  carbonate  than 
the  concentrated  liquid.  Add  water  to  the  carbonate  to  make  a  thin  paste,  pour  on 
about  half  of  the  diluted  ammonia  and  stir  vigorously  for  several  minutes:  allow  it 
to  settle  and  pour  off  the  solution  leaving  the  undisturbed  salt  behind.  Repeat 
this  operation,  using  small  portions  of  the  remaining  ammonia  water  until  all  the 

669 


670  ADDITIONAL   EXERCISES 

carbonate  is  dissolved,  being  careful  to  use  no  more  ammonia  than  is  necessary  to 
complete  the  solution.  Then,  after  adding  the  remainder  of  the  required  quantity 
of  water,  the  solution  is  ready  for  application. 

Caution. — Plants  likely  to  be  injured  by  Bordeaux  mixture  are  more  susceptible 
to  the  clear  light-blue  solution  of  ammoniacal  copper  carbonate,  which  upon  drying 
leaves  little  or  no  stain. 

Arsenate  of  lead  is  one  of  the  best  arsenical  insecticides.  It  has  in  many  cases 
entirely  displaced  Paris  green  orchard  spraying,  and  there  are  at  least  three  good 
reasons  for  its  use. 

First. — The  arsenate  of  lead  has  great  adhesive  qualities.  It  will  not  wash  off 
even  in  heavy  showers  of  rain.  Some  of  the  experiments  at  the  Minnesota  Experi- 
ment Station  showed  the  presence  of  this  arsenate  on  the  leaf  in  sufficient  quantity 
to  kill  insects,  ten  weeks  after  spraying. 

Second. — It  can  be  used  in  any  strength  without  burning  the  foliage  of  the  plant 
sprayed,  except  peach  leaves  which  are  burned,  if  it  is  too  strong. 

Third. — It  has  some  fungicidal  properties  that  are  increased  when  added  to  lime 
sulphur.     The  home-made  preparation  is  made  as  follows : 

22  ounces  acetate  of  lead  (sugar  of  lead)  dissolved  in  2  gallons  of  warm  water  in 
a  wooden  pail. 

8  ounces  arsenate  of  soda  dissolved  in  i  gallon  water  in  another  wooden  pail. 
These  two  solutions  are  poured  together  and  make  sufficient  quantity  of  poison  for 
50  gallons  of  spray. 

Arscnite  of  Lime. — A  home-made  preparation  much  cheaper  than  Paris  green 
and  just  as  good.     It  is  prepared  as  follows: 

White  arsenic,  i  pound       ] 

Crystal  sal  soda,  4  pounds  [    Stock  solution 

Water,  i  gallon  J 

Boil  these  in  an  iron  kettle  for  twenty  minutes  until  thoroughly  dissolved.  The 
kettle  must  be  kept  exclusively  for  this  purpose.  The  soluble  material  obtained  is 
arsenite  of  soda  and  can  be  stored  away  in  jugs  or  bottles,  labeled  poison,  for  future 
use.  For  40  or  50  gallons  of  spray,  take  1 3^  to  2  pints  of  this  solution,  and  4  pounds 
of  freshly  slaked  lime.  Dilute  the  lime  and  stain:  then  add  the  stock  solution. 
Pour  into  the  spray  barrel,  and  it  is  ready  for  use. 

Bordeaux  Mixture. — This  is  the  most  valuable  fungicide  in  use  for  combating 
plant  diseases  and  consists  of  a  mixture  of  copper  sulphate  (blue  stone)  and  stone 
lime  slaked  in  water.     It  is  used  in  various  strengths. 

Standard  Bordeaux  Mixtures  (Fig.  237)   (6-4-50  formula). 

Copper  sulphate,  6  pounds. 

Lime,  4  pounds. 

Water  to  make  50  gallons.. 

This  mixture  can  be  used  successfully  on  many  plants,  but  on  others  like  the  peach 
and  Japanese  plum,  it  injures  the  foliage.  It  also  sometimes  russets  the  fruit  of 
apples  and  pears.     It  can  be  increased  in  strength  for  certain  purposes  by  reducing 


APPENDIX    I  671 

the  proportion  of  water,  but  the  formula  given  above  has  been  regarded  as  the 
standard  with  which  all  others  should  be  compared,  at  least  in  experimental  work. 
The  5-5-50  Formtda. — Here  the  preparation  consists  of 

Copper  sulphate,  5  pounds. 

Lime,  5  pounds. 

Water  to  make  50  gallons. 

The  use  of  this  formula  is  desirable  where  the  purity  of  the  lime  is  in  doubt,  as 
it  makes  certain,  with  lime  of  any  reasonable  quality,  that  all  of  the  copper  is  properly 
neutralized.  The  danger  of  scorching,  or  russeting  fruit  is,  therefore,  less.  With- 
holding I  pound  of  the  copper  sulphate  also  cheapens  the  mixture  by  a  few  cents. 
For  these  reasons  the  5-5-50  formula  has  come  to  be  quite  generally  used  in  orchard 
spraying.  In  fact,  it  has  almost  replaced  the  old  standard  Bordeaux  mixture  in 
spraying  for  the  apple  scab,  bitter-rot,  pear  and  cherry  leaf-blight  and  similar  diseases. 

The  4-4-50  and  Other  Formulas.— The  strength  of  the  mixture  is  often  further 
reduced  by  using  the  4-4-50  formula,  but  it  is  questionable  whether  it  pays  to  reduce 
the  strength.  For  use  as  a  whitewash,  a  very  concentrated  mixture,  6-4-20,  may 
be  desirable  and  for  certain  diseases  Bordeaux  mixture  can  be  diluted  so  as  to  be 
equivalent  to  6-4-100. 

The  form  of  Bordeaux  mixture  most  harmless  to  foliage  is  3-9-50,  having  a  con- 
siderable excess  of  lime.     This  may  be  known  as  the  "peach  Bordeaux  mixture." 

Various  modifications  of  the  original  Bordeaux  mixture  have  been  suggested  and 
tried.  The  principal  ones,  however,  are  the  "soda  Bordeaux  mixture"  and  the 
"potash  Bordeaux  mixture."  The  former  consists  of  6  pounds  of  copper  sulphate, 
2  pounds  of  caustic  soda  and  50  gallons  of  water.  The  latter  is  the  same  except  an 
equal  quantity  of  caustic  potash  is  substituted  for  the  soda.  Other  materials  are 
sometimes  added  to  Bordeaux  mixture  to  increase  its  spreading  power.  The  most 
successful  is  ordinary  hard  soap,  dissolved  in  hot  water  and  added  at  the  rate  of  4 
pounds  to  the  barrel,  and  this  modified  Bordeaux  mixture  is  known  as  "soap 
Bordeaux." 

Bordeaux  Resin  Mixture  (N.  Y.  (Geneva)  Bull.  No.  188,  1900). 

Resin,  5  pounds. 
Potash  lime,  i  pound. 
Fish  oil,  I  pint. 
Water,  5  gallons. 

Add  to  Bordeaux  as  directed  below.  To  prepare  a  stock  resin  solution  proceed 
as  follows:  "Place  the  oil  and  resin  in  the  kettle,  heating  them  until  the  resin  is  dis- 
solved, then  remove  the  kettle  from  the  fire  and  allow  the  mass  to  cool  slightly,  after 
which  the  solution  of  lye  is  added  slowly,  the  whole  being  stirred  while  adding  the 
lye.  After  adding  the  lye  the  kettle  should  be  again  placed  over  the  fire  and  the 
required  amount  of  water  added.  The  whole  should  be  boiled  until  the  solution 
will  mix  with  cold  water  forming  an  amber-colored  solution.  Care  should  always 
be  taken  to  have  the  resin  and  oil  cool  enough,  so  that  when  the  solution  of  lye  or  the 
water  is  added  the  whole  mass  will  not  boil  over  and  catch  fire. 


672 


ADDITIONAL   EXERCISES 


"Dilute  this  stock  resin  solution  with  8  parts  of  water  before  adding  to  the 
Bordeaux  mixture,  that  is  in  preparing  a  50-gallon  barrel  of  the  mixture,  the  copper 
sulphate  and  lime  are  diluted  enough  to  make  40  gallons  after  which  2  gallons  of 
stock  resin  solution  are  diluted  to  10  gallons,  then  added  to  the  Bordeaux." 

This  solution  exceeds  ordinary  Bordeaux  in  adhesive  properties  and  has  been 
highly  recommended  for  asparagus  rust. 

Method  of  Making  Small  QiiantUies  of  Bordeaux  Mixture. — Two  half-barrel  tubs 
are  made  by  sawing  a  barrel  through  the  middle.  One  tub  is  used  for  the  blue-stone 
solution  and  the  other  for  the  milk  of  lime,  and  each  tub  should  contain  25  gallons. 
One  man  dips  the  blue-stone  solution  with  a  bucket  and  pours  it  into  a  barrel  and 
another  man  simultaneously  dips  up  and  pours  in  bucketfuls  of  the  milk  of  lime. 


DIP  EQUAL  PARTS  FROM 

-     I ^3ss5^      anp2into3 

'EST0KE*^SVrHEN5Tifi 

IGOR- 
,  0U5LY 


fine  mesh  screen 
nelto 
leoux 


Sprayer 


Dipper-*  mil-: 

"t/se  thi5  miiiturf  at  once  m&pi^cr- 
FiG.   237. — Diagram  showing  easy  method  of  making-small  quantities  of  Bor- 
deaux mixture.      {After  Coons,  G.  H.,  and  Levin,  Ezra,  Spec.  Bull.  77,  Mich.  Agric. 
Coll.  Exper.  Stat.,  March,  1916.) 

The  lime  solution  should  be  kept  well  stirred.  If  only  a  single  barrel  is  to  be  made, 
the  materials  may  be  dissolved  in  the  dilution  tubs,  but  if  a  number  of  lots  are  re- 
quired the  materials  can  be  kept  in  stock  solutions  and  simply  transferred  by  dipping. 
No  matter  what  quantity  of  mixture  is  to  be  made  up,  it  is  necessary  to  strain  the 
materials  through  a  wire  strainer.  The  best  type  is  made  of  brass  wire  with  18  to 
20  meshes  to  the  inch  (Fig.  237).  For  details  see  Waite,  M.  B.:  Fungicides. 
U.  S.  Farmers'  Bull.  243  (1906). 

In  large  operations  stock  solutions  should  always  be  used,  as  the  time  required  to 
dissolve  the  material  is  saved.  These  can  be  prepared  of  both  copper  sulphate  and 
the  lime.  Dissolve  copper  sulphate  in  water  at  the  rate  of  i  pound  per  gallon  and 
lime  in  the  same  ratio.  Then  measure  ofT  the  required  quantity  of  each  and  dilute 
with  water  before  mixing.  If  possible  the  dilution  tanks  should  be  raised  so  high 
on  an  elevated  platform  that  the  mixture  can  be  conducted  by  gravity  into  the 
spray  tank  on  wheels  or  in  a  wagon  beneath.     An  available  water  supply  is  necessary. 


APPENDIX   1  673 

Testing  Bordeaux  Mixliirc.—When  Bordeaux  mixture  is  properl)'  prepared  it  is  of 
a  brilliant  sky-blue  color.  If  the  lime  is  air-slaked,  or  otherwise  inferior  in  quality, 
resulting  in  a  bad  mixture,  the  preparation  will  have  a  greenish  cast,  and  if  this  is 
very  pronounced  the  mixture  will  injure  the  foliage.  In  order  to  make  certain  that 
the  copper  sulphate  is  properly  neutralized  by  the  lime,  the  yellow  prussiate  of  potash 
test  may  be  used.  A  small  bottle  containing  a  10  per  cent,  solution  of  yellow 
prussiate  of  potash  can  be  secured  from  a  druggist.  After  stirring  the  Bordeaux 
mixture  a  drop  of  this  solution  is  allowed  to  fall  on  the  surface  of  the  preparation. 
If  free  copper  is  present,  the  drop  will  turn  reddish  brown  in  color  immediately. 
Lime  should  then  be  added  until  the  brown  color  fails  to  appear.  If  the  reaction 
is  complete,  the  yellow  prussiate  of  potash  solution  will  remain  a  clear  yellow  until 
it  disappears  in  the  mixture. 

Bordeaux  Mixture  and  Inseclicides. — One  advantage  of  Bordeaux  mixture  is  the 
possibility  of  adding  arsenical  insecticides  to  the  preparation  and  thus  of  spraying 
at  the  same  time  for  :(,ungous  diseases  and  for  the  codling-moth  and  leaf-eating  in- 
sects. Paris  green  at  the  rate  of  yi  pound  to  50  gallons  of  Bordeaux  mixture,  may 
be  considered  as  the  standard  formula  for  this  purpose.  London  purple,  arsenate  of 
lead  and  other  arsenicals  may  be  used  in  the  same  way.  Bordeaux  mixture  may  be 
considered  as  so  much  water  in  the  formulas  for  this  class  of  insecticides.  As  a 
matter  of  fact,  the  slight  excess  of  lime  in  the  standard  mixture  renders  it  an  espe- 
cially suitable  medium  for  distributing  these  insecticides. 

Dust  Bordeaux  Mixture. — This  mixture  is  prepared  as  follows: 

4  pounds  of  copper  sulphate  in  4  gallons  of  water. 
4  pounds  of  lime  in  4  gallons  of  water. 
60  pounds  of  slaked  lime  dust. 

Dissolve  the  4  pounds  of  copper  sulphate  in  4  gallons  of  water  and  slake  4  pounds 
of  lime  in  4  gallons  of  water,  when  cold  pour  the  two  solutions  together  simultaneously 
into  a  tub.  Allow  the  resulting  precipitant  to  settle,  decant  off  the  liquid,  pour 
the  wet  mass  of  material  into  a  double  flour  bag,  and  squeeze  out  as  much  water  as 
possible.  Then  spread  the  dough-like  mass  in  the  sun  to  dry.  After  a  day's  dry- 
ing it  can  be  crumbled  easily  into  an  impalpable  powder  by  crushing  with  a  block 
of  wood.  This  powder  should  be  screened  through  a  brass  wire  sieve  having  at  least 
83  meshes  to  the  inch  and  should  be  mixed  thoroughly  with  60  pounds  of  slaked  lime 
dust.  The  lime  dust  is  best  prepared  by  slowly  sprinkling  a  small  quantity  of  water 
over  a  heap  of  quick  lime,  using  barely  enough  water  to  cause  the  lime  to  crumble 
into  a  dust.  The  heat  generated  will  soon  drive  off  the  excess  of  moisture,  and  the 
dust  should  be  passed  through  a  screen  of  80  meshes  to  the  inch.  This  powder  is 
applied  by  means  of  a  blower.  If  desired  4  pounds  of  sulphate  and  i  pound  of  Paris 
green  may  be  added  to  each  60  pounds  of  Bordeaux  mixture  dust.  For  details, 
consult  Waite   M.  B.:  Fungicides.     U.  S.  Farmers'  Bull.  No.  243  (1906). 

Copper  Sulphate  Wash. 

Copper  sulphate,  3  pounds. 
Water,  50  gallons. 


674  ADDITIONAL   EXERCISES 

This  is  used  as  a  wash  on  dormant  trees,  for  the  prevention  of  such  diseases 
as  apple  scab.     It  must  never  be  used  on  trees  after  the  buds  have  burst. 
-    Copper  Acetate. 

Copper  acetate  (dibasic  acetate),  6  ounces. 
Water,  50  gallons. 

First  make  a  paste  of  the  copper  acetate  by  adding  water  to  it,  then  dilute  to 
the  required  strength.  Use  finely  powdered  acetate  of  copper,  not  the  crystalline 
form.     It  may  be  used  as  a  substitute  for  copper  carbonate  mixtures. 

Copper  Saccharate. — Consult  Freemen,  E.  M.:  Minnesota  Plant  Diseases,  p.  220. 

Corrosive  Sublimate. 

Mercury  bichloride  (corrosive  sublimate),  2  ounces.. 
Water,  15  gallons. 

This  is  an  extremely  poisonous  mixture  and  should  be  handled  with  great  care. 
It  is  very  effective  against  potato  scab.     It  should  not  be  made  in  tin  vessels,  as  it 
corrodes  them. 
Formalin. 

Formalin  (40  per  cent,  formaldehyd),  J-2  pound. 
Water,  15  gallons. 

This  is  used  in  treating  seed  for  prevention  of  such  diseases  as  potato  scab. 
Iroti  Sulphide  Mixture. — This  is  a  new,  but  very  promising  fungicide.  It  was 
tried  on  apples,  and  gave  splendid  results  in  preventing  fungous  diseases,  being  non- 
injurious  to  the  fruit.  In  preparing  this  fungicide,  it  is  recommended  that  a  self- 
boiled  lime-sulphur  mixture  be  prepared,  as  later  described,  except  that  10  pounds 
of  lime  and  10  pounds  of  sulphur  are  used.  The  mixture  is  diluted  to  40  gallons, 
and  then  3  pounds  of  iron  sulphate  (copperas)  dissolved  in  about  8  gallons  of  water, 
is  added. 

Potassium  Sulphide  (Liver  of  Sulphur). 

Potassium  sulphide,  3  to  5  ounces. 
Water,  10  gallons. 

This  is  used  in  place  of  Bordeaux  mixture  to  avoid  spotting  of  foliage  and  fruit. 
It  is  considered  to  be  especially  effective  against  powdery  mildews.  It  is  quite  ex- 
tensively used  in  greenhouses  and  on  shrubbery. 

Sulphur. — Is  used  as  a  fungicide  in  a  pure  state.  The  flowers  of  sulphur  is  the 
highest  and  usually  the  purest  chemically.  It  is  dusted  on  plants  as  a  remedy  for 
mildew,  especially  the  rose  mildew  and  the  powdery  grape  mildew. 

Sulphur  and  Resin  Solution. — It  is  made  up  as  follows : 

Sulphur  (flowers,  or  flour),  16  pounds. 
Resin  (finely  powdered),  3^2  pound. 
Caustic  soda  (powdered),  10  pounds. 
Water  to  make  6  gallons. 

Place  the  sulphur  and  resin,  thoroughly  mixed,  in  a  barrel  or  smaller  vessel, 


APPENDIX   I  675 

and  make  a  thick  paste  by  the  addition  of  about  3  quarts  of  water.  Then  stir  in 
the  caustic  soda.  After  several  minutes,  the  mass  will  boil  violently,  turning  a 
reddish-brown,  and  should  be  stirred  thoroughly.  After  boiling  has  ceased,  add 
about  2  gallons  of  water  and  pour  off  the  liquid  into  another  vessel,  and  add  to  it 
sufficient  water  to  make  6  gallons.  This  form  of  stock  solution  may  be  used  at  the 
rate  of  i  gallon  to  50  of  water  for  spraying  mOst  plants  and  for  soaking  seeds. 
Eati  Celeste  (Modified). — It  is  made  as  follows: 

Copper  sulphate,    4  pounds. 
Ammonia,  3  pints. 

Sal  goda,  5  pounds. 

Water  to  make     45  gallons. 

Dissolve  the  copper  sulphate  in  10  or  12  gallons  of  water,  add  the  ammonia,  and 
dilute  to  45  gallons;  then  add  the  sal  soda  and  stir  until  dissolved.  Eau  celeste  is 
an  effective  dormant  spray  for  the  peach  leaf-curl  and  other  similar  diseases,  but  it  is 
unsafe  to  use  on  the  foliage  of  most  plants. 

Polassinm  Permanganate.     (Not  used  in  the  United  States.) 

Potassium  permanganate,      i  part. 
Soap,  2  parts. 

Water,  100  parts. 

Recommended  in  France  for  black-rot  and  mildew  of  grape,  etc. 
Iron  Sulphate  and  Sulphuric  Acid. 

Water  (hot),  100  parts. 

Iron  sulphate,  as  much  as  will  dissolve. 

Sulphuric  acid,  i  pint. 

Prepare  the  solution  Just  before  using.  Add  the  acid  to  the  crystals  and  then 
pour  on  the  water.  Valuable  for  treatment  of  dormant  grape  vines  affected  with 
anthracnose,  applications  being  made  with  sponge  or  brush  from  wooden  vessels  in 
which  it  is  made.  The  solution  will  destroy  the  foliage,  so  it  must  be  used  in  late 
fall,  or  early  spring,  or  applied  only  to  tree  trunks. 

Lime-sulphur. — Within  the  last  few  years  this  wash  has  come  into  prominence  as 
one  of  the  best  Scale  insecticides  discovered.  Several  forms  of  it  are  excellent 
fungicides.     Three  formulae  are  here  given. 

The  Boiled  Mixture  (home-made). 

Best  stone  lime,  15  pounds. 
Flowers  of  sulphur,  15  pounds. 
Water,  15  gallons. 

Slake  the  lime  in  a  small  quantity  of  hot  water,  add  the  sulphur  gradually  and 
stir  thoroughly.  Dilute  the  mixture  to  15  gallons  with  water,  and  boil  in  an  iron 
kettle,  or  cook  by  steam  in  a  barrel  for  forty-five  minutes.  Fill  the  vessel  with  water 
to  the  required  50  gallons;  strain  the  wash  through  a  fine-mesh  strainer  and  apply 


676  ADDITIONAL    EXERCISES 

hot.     This  wash  should  be  applied  in  the  fall  after  the  leaves  have  dropped,  or  in  the 
spring  before  the  buds  open."    Spray  thoroughly,  covering  all  parts  of  the  tree. 
Concentrated  Mixture. 

Sulphur,  80  pounds. 

Best  stone  lime  (95  per  cent,  calcium  oxide),  40  pounds. 
Water,  50  gallons. 

Live  steam  run  in  a  barrel,  or  fire  under  an  iron  kettle  may  be  used  in  boiling. 
Place  5  gallons  of  water  and  40  pounds  of  the  sulphur  in  the  vessel,  and  apply  heat 
until  the  sulphur  becomes  a  smooth  paste,  stirring  constantly.  Now  add  10  gallons 
of  water  and  20  pounds  of  lime  and  boil  for  forty-five  minutes.  Add  water  to  make 
25  gallons.  .  When  cooled  to  3S°F.  test  with  Baume  scale;  the  reading  should  be 
about  33°F.  As  a  scalecide  to  use  in  the  dormant  season,  this  should  be  diluted 
I  to  10  (i.e.  I  part  of  the  above  formula  diluted  with  9  parts  of  water)  and  6  to  10 
pounds  of  stone  lime  added  to  every  50  gallons  of  the  spray.  As  a  fungicide  for 
summer  use,  dilute  i  to  30  (i  part  of  stock  solution  to  29  parts  of  water).  When 
stored  away  it  is  best  to  cover  the  solution  with  a  layer  of  oil  about  an  eighth  of  an 
inch  thick.  This  will  prevent  evaporation  and  the  forming  of  a  crust  on  the 
material.  The  material  should  not  be  stored  where  the  temperature  will  go  very 
low. 

Self-boiled  Lime  Sulphur. 

Lime,  8  pounds. 
Sulphur,  8  pounds. 
Water,   50  gallons. 

This  spray  is  valuable  in  cases  where  Bordeaux  is  injurious  to  foliage  or  fruit. 
The  stone  fruits,  such  as  plums,  are  particularly  susceptible  to  Bordeaux  injury, 
while  some  varieties  of  apples  are  badly  russeted  by  it.  There  is  slight  danger  of 
injury  by  the  self-boiled  lime-sulphur  preparation,  and  it  is  an  efficient  fungicide 
when  properly  made.  It  stains  the  fruit  as  does  Bordeaux.  In  making  it  8  pounds 
of  lime  of  good  quality  should  be  placed  in  a  barrel,  and  enough  water  to  nearly 
cover  it  should  be  added.  While  the  lime  is  slaking,  add  sulphur  which  has  run 
through  a  sieve  to  break  up  the  lumps.  The  sulphur  should  be  stirred  thoroughly 
into  the  slaking  lime,  enough  water  being  added  to  make  a  pasty  mass.  The  barrel 
should  now  be  covered,  in  order  to  retain  its  heat,  and  the  contents  should  be  occa- 
sionally stirred.  The  time  required  varies  with  the  quality  of  the  lime;  if  the  lime 
acts  quickly,  five  to  ten  minutes  would  be  sufficient,  while  if  it  acts  slowly,  fifteen 
minutes  may  be  necessary.  It  should  not  be  allowed  to  stand  too  long,  because  it 
may  in  that  case  be  injurious  to  foliage.  Now  add  water,  stirring  the  mixture 
while  it  is  being  poured  in.  Then  add  enough  water  to  bring  the  total  up  to  50 
gallons.  In  applying  the  spray,  it  is  necessary  to  have  a  good  agitator  in  the  sprayer. 
Consult  RuGGLES,  A.  G.,  and  Stakman,  E.  C.  :  Orchard  and  Garden  Spraying.  Bull. 
No.  121,  Agric.  Exper.  Sta.  Univ.  Minn.,  March,  191 1.  Also  Duggar,  B.  M.,  and 
CooLEY,  J.  S.:  The  Effect  of  Surface  Films  and  Dusts  on  the  Rate  of  Transpiration. 
Ann.  Mo.  Bot.  Gard.,  I:  pp.  1-22,  March,  1914. 


APPENDIX    I  677 

Lime-sulphur  Salt  Wash. — This  wash,  although  rarely  used,  is  made  as  follows: 

Lime,  unslaked,  20  pounds. 

Sulphur  (flour,  or  flowers),  15  pounds. 
Salt,  10  pounds. 

Water  to  make  50  gallons. 

Many  different  formulas  are  used  in  making  up  this  wash  but  the  above  formula 
seems  to  be  the  best,  and  has  been  extensively  used.  If  the  lime  is  high-grade  stone 
lime,  15  pounds  will  be  sufficient  to  dissolve  all  the  sulphur.  With  average  lime 
20  pounds  is  the  better  quantity,  but  with  poor  or  partly  air-slaked  lime  25  to  30 
pounds  are  necessary.  Lime  absorbs  an  equal  weight  of  water  in  becoming  air- 
slaked. 

To  prepare  small  quantities  of  this  wash  proceed  as  follows:  Place  about  10 gal- 
lons of  water  in  an  iron  kettle  over  a  fire,  make  the  sulphur  into  a  paste  with  a  little 
water,  and  when  the  boiling  point  is  nearly  reached  add  the  fresh  lime  and  the  sul- 
phur together.  The  mixture  should  be  constantly  stirred,  and  the  boiling  continued 
for  forty  to  sixty  minutes.  The  object  of  the  cooking  is  to  dissolve  the  sulphur  and 
when  this  is  accomplished  further  boiling  is  useless,  but  not  harmful.  The  salt  may 
be  added  at  any  time  during  the  process  of  boiling,  or  entirely  omitted.  It  is  gener- 
ally conceded,  however,  that  salt  increases  the  adhesiveness  of  the  wash,  as  it  does 
ordinary  lime  whitewash,  and  for  this  reason,  it  is  perhaps  advisable  to  use  it,  al- 
though it  is  not  supposed  to  strengthen  the  fungicidal  property  of  the  mixture. 
Possibly  also  the  salt  hastens  the  solution  of  the  sulphur  by  raising  the  boiling  point, 
or  by  its  solvent  action. 

It  has  been  found  that  the  sulphur  dissolves  more  readily  in  a  concentrated  mix- 
ture with  lime,  and  the  quantity  of  water  used  during  the  process  of  boiling  should, 
therefore,  be  reduced  to  a  minimum.  The  mixture  should  not  be  allowed  to  become 
pasty,  however,  and  water,  preferably  hot,  should  generally  be  added  until  the  barrel 
is  nearly  full  when  finished.  When  the  cooking  is  completed,  pass  the  mixture 
through  an  iron  wire  strainer  (not  brass  or  copper),  and  dilute  with  the  required 
amount  of  water.  For  details,  see  Waite,  M.  B.:  Fungicides  and  Their  Use  in 
Preventing  Diseases  of  Fruits.     U.  S.  Farmers'  Bull.  No.  243  (1906). 

The  wash  may  be  applied  either  hot  or  cold  with  practically  the  same  results, 
though  the  warm  mixture  is  less  likely  to  clog  the  nozzles.  If  allowed  to  stand  over 
night,  sulphur  crystals  will  form  on  the  bottom  and  sides  of  the  containing  vessel. 
It  is  difficult  to  dissolve  the  lime-sulphur  crystals  after  they  have  once  formed.  For 
this  reason,  it  is  better  not  to  prepare  more  than  can  be  used  the  same  day. 

Steeps. — Solutions  in  use  for  dipping  seeds,  fruits  and  the  like  in  order  to  control, 
or  check  fungous  diseases. 

Formalin. — (.4)  For  oat  smut  and  stinking  smut  of  wheat.  Add  }/-},  pound  of 
formalin  to  30  gallons  of  water  and  immerse  the  seed  grain  for  two  hours,  then  spread 
out  and  dry:  or  sprinkle  the  grain  with  the  formalin  solution  until  thoroughly  wet, 
shoveling  over  rapidly  to  distribute  the  moisture  evenly,  then  place  in  a  pile  (covered 
with  sacking)  for  two  hours  and  finally  spread  out  to  dry  as  in  the  first  method. 

{B)  For  potato  scab.     The  formalin  treatment  of  seed  potatoes  practically  frees 


678  ADDITIONAL   EXERCISES 

the  seed  from  scab  with  slight  expense  and  trouble.  Add  ^^'2  pound  of  formalin  to 
15  gallons  of  water  and  immerse  the  seed  tubers  for  two  hours.  The  seed  tubers 
are  then  spread  in  thin  layers  to  dry  promptly.  After  removing  from  the  solu- 
tion, cut  and  plant  as  usual-. 

Hot  Water  Method  for  Smuts  (Jensen)  (consult  Freemen,  E.  M.:  Minnesota 
.Plant  Diseases,  p.  225). — Provide  two  large  vessels,  preferably  holding  at  least  20 
gallons.  Two  wash  kettles,  soap  kettles,  wash  boilers,  tubs  or  even  barrels,  will  do. 
One  of  the  vessels  should  contain  warm  water,  say  at  110°  to  i2o°F.  and  the  other 
scalding  water,  at  132°  to  i33°F.  The  first  is  for  the  purpose  of  warming  the  seed 
preparatory  to  dipping  it  into  the  second.  Unless  this  precaution  is  taken,  it  will 
be  difficult  to  keep  the  water  in  the  second  vessel  at  the  proper  temperature.  A 
pail  of  cold  water  should  be  at  hand,  and  it  is  also  necessary  to  have  a  kettle  filled 
with  boiling  water  from  which  to  add  from  time  to  time  to  keep  the  temperature 
right.  Where  kettles  are  used,  a  small  fire  should  be  kept  under  the  kettle  of  scald- 
ing water.  The  seed  which  is  to  be  treated  must  be  placed,  half  a  bushel  or  more  at 
a  time,  in  a  closed  vessel  that  will  allow  free  entrance  and  exit  of  water  on  all  sides. 
Hence  a  gunny  bag,  or  sac,  can  be  used  for  this  purpose.  Now  dip  the  basket,  or 
bag,  of  seeds  into  the  water  at  110°  to  i2o°F.  and  lifting  it  out  plunge  it  into  the 
second  vessel  containing  water  at  132°  to  i33°F.  After  removing  the  grain  from  the 
scalding  water,  spread  it  on  a  clean  floor,  or  piece  of  canvas  to  dry. 

Corrosive  Sublimate. 

Corrosive  sublimate,  2  ounces. 
Water,  15  gallons. 

Dissolve  the  corrosive  sublimate  in  2  gallons  of  hot  water,  then  dilute  to  15 
gallons,  allowing  the  same  to  stand  five  or  six  hours,  during  which  time  thoroughly 
agitate  the  solution  several  times.  Place  the  seed  potatoes  in  a  sack  and  immerse 
in  the  solution  for  one  and  a  half  hours,  and  then  spread  to  dry. 

Insecticides  Used  to  Kill  Insects 

Carbon  Bisulpkid. — This  inflammable  and  volatile  liquid  is  used  against  grain 
weevils  and  against  the  insects  that  are  destructive  to  herbarium  specimens. 

Crude  Petroleum. — This  is  an  oily  inflammable  liquid  used  against  scale  insects. 

Hellebore.- — This  is  a  stomach  or  internal  insecticide.  It  is  not  poisonous  to  man 
as  are  the  arsenical  insecticides,  and  is  used  where  there  is  danger  of  poison  remain- 
ing on  parts  to  be  eaten.  It  is  often  used  on  currants  and  gooseberries  when  the 
berries  are  beginning  to  ripen.  It  is  used  in  the  dry  form,  and  must  be  fresh 
when  used. 

Hydrocyanic  Gas. — This  gas  is  made  by  dropping  potassium  cyanide  into  sul- 
phuric acid  and  water.  The  fumes  are  deadly  to  all  kinds  of  animal  life,  and  the  gas 
is  used  only  in  special  cases. 

Kerosene. — This  is  an  excellent  contact  insecticide.  Pure  kerosene,  however, 
will  ordinarily  burn  the  leaves  of  plants,  consequently  it  is  used  in  pure  form  when 
trees  are  dormant,  or  against  insects  off'  of  plants  as  grasshoppers,  household  insects, 
etc. 

Kerosene  Emulsion. — This  is  probably  the  best  form  in  which  kerosene  can  be 
used.     A  stock  emulsion  is  made  as  follows: 


APPENDIX   I  679 

Hard  laundry  soap  (shaved  fine),  ^^  pound. 
Water,  i  gallon. 

Kerosene,  2  gallons. 

Dissolve  the  soap  in  boiling  water,  remove  from  the  stove,  and  immediately  add 
the  kerosene;  churn  with  a  bucket  pump  until  a  soft,  butter-like,  clabbered  mass  is 
obtained.  One  part  of  this  stock  is  added  to  10  to  12  of  soft  water.  If  the  stock 
solution  is  properly  made  this  can  be  used  on  tender  foliage  of  plants  for  such  insects 
as  plant-lice,  etc. 

Lime  Sulphur. — See  ante. 

Miscible  oils  are  those  that  will  mix  with  water.  There  are  several  oils  on  the 
market  that  are  miscible  in  water.  These  make  a  good  winter  spray  for  scales  and 
are  also  excellent  summer  sprays  against  the  same  insects.  Great  care,  however, 
must  be  taken  to  get  the  right  dilution,  or  burning  of  the  leaves  will  result. 

Paris  Green  is  used  by  many  where  an  arsenical  insecticide  is  necessary.  It  is 
generally  used  at  the  rate  of  i  pound  to  50  gallons  of  spray.  In  using,  always  first 
make  a  paste  of  the  Paris  green  and  water,  and  then  add  to  the  spray  material. 

Pyrethrum,  or  Insect  Powder  (Persian  insect  powder,  Dalmatian  powder,  or 
Buhach). — This  is  a  powder  from  the  ground-up  flowers  of  the  pyrethrum  plant. 
•It  is  a  contact  insecticide  and  is  used  against  fleas,  cockroaches,  etc.  If  the  powder 
is  burned  in  a  room  the  fumes  will  destroy  mosquitoes  and  flies. 

Resin  Lime  Mixture. — Used  with  a  fungicide,  or  insecticide,  to  insure  sticking 
of  poisonous  material  to  smooth,  glossy  leaves. 

Pulverized  resin,  5  pounds. 

Concentrated  lye,  i  pound. 

Fish,  or  other  animal  oil,  i  pint. 
Water,  5  gallons. 

Place  the  oil,  the  resin  and  i  gallon  of  water  in  an  iron  kettle  and  heat  until  the 
resin  softens;  then  add  the  lye  and  stir  thoroughly.  Add  to  this  4  gallons  of  hot 
water,  and  boil  until  a  little  mixed  with  cold  water  gives  a  clear,  amber-colored 
liquid.  Add  water  to  make  up  to  5  gallons.  This  is  a  stock  solution.  In  spraying 
with  Paris  Green,  or  Bordeaux  mixture,  take  2  gallons  of  this  mixture,  dilute  it  to 
10  gallons,  and  add  40  gallons  of  spray. 

Soap. — Ordinary  soap  is  a  valuable  contact  insecticide. 
Ivory  soap,     i  pound. 
Water,  14  gallons. 

Boil  the  soap  in  5  to  6  gallons  of  water  until  dissolved,  dilute  with  water  to  14 
gallons  and  spray  while  still  warm.     It  is  recommended  for  plant-lice,  red  spiders,  etc. 
Sulphur. — Flowers  of  sulphur  is  often  dusted  on  ornamental  plants  to  prevent 
such   diseases,  as  powdery  mildews,  and  spots,  2  parts  of  sulphur  and  i  part  of 
air-slaked  lime. 

Tobacco  is  a  very  important  contact  insecticide.  As  a  powder  it  is  one  of  the  best 
remedies  for  root-lice  on  trees.  As  a  decoction  it  may  be  used  as  a  spray  against 
plant-lice.     Tobacco  smoke  kills  soft-bodied  insects. 

Whale  Oil  Soap  (Fish-oil  Soap). — This  is  a  commercial  product,  and  is  a  good 
contact  insecticide,  particularly  for  soft-bodied  insects,  like  plant-lice. 


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Fig.   238. — Spray  pumps  isolated  and  with  bucket  attachments. 


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Fig.  239. — Spray  barrel  with  pump. 


692  ADDITIONAL   EXERCISES 

Spraying  Apparatus.- — Various  forms  of  spraying  apparatus  are  upon  the  market 
for  use  in  the  different  operations  of  spraying.  The  student  is  directed  to  trade 
catalogs  and  to  special  treatises  on  the  subject  for  details. 

We  may,  as  an  introduction  to  this  subject,  classify  the  types  of  spraying  outfits 
into:  Bucket  pumps  (Fig.  238),  knapsack  sprayers  (Fig.  238),  barrel  pumps  (Fig. 
239),  the  tank  outfit,  geared  sprayers,  steam  and  gasoline  outfits,  etc. 

The  question  of  details  resolves  itself  into  a  consideration  of  hose,  extension 
rods,  nozzles,  force  pumps,  wagons,  push  carts  and  receptacles  for  the  spray  materials 
(for  outfit  see  page  672).  For  these  details  and  a  list  of  firms  dealing  in  spraying 
apparatus,  consult  a  bulletin  by  C.  A.  McCue  entitled  Plant  Protection,  Bull.  No.  97, 
Del.  Col.  Agric,  Exper.  Sta.,  June  15,  191 2. 

APPENDIX  III 

Antisepsis  and  Disinfection. — An  antiseptic  is  a  substance  which  acts  to  the  ex- 
clusion from  wounds  of  living  organisms  that  cause  putrefaction,  or  decay. 

Liquor  Antisepticus. — 155  grains  of  boric  acid  should  be  dissolved  in  113-^  ounces 
of  water,  and  7  grains  of  benzoic  acid  in  2  3'2  ounces  of  alcohol,  and  the  two  liquids 
then  mixed.  After  dissolving  7  grains  of  thymol  in  a  mixture  of  8  drops  of  oil  of 
peppermint  4  drops  each  of  eucalyptol  and  oil  of  gaultheria  and  i  drop  of  oil  of  thyme, 
triturate  with  155  grains  of  purified  talc  and  add  the  solution  of  benzoic  and  boric 
acids.  Shake  occasionally  during  forty-eight  hours,  filter  and  add  to  the  clear  fil- 
trate first  i^i  ounces  of  alcohol,  and  then  sufficient  water  to  bring  the  volume  up 
to  I  pint. 

Formalin. — Has  powerful  antiseptic  properties.  It  is  sold  in  40  per  cent, 
solution  and  can  be  distilled  with  water  to  the  required  strength. 

Corrosive  Sublimate  (Bichlorid  of  mercury). — It  is  used  in  solution  in  water  in 
a  strength  of  i  :  1000. 

Definition  of  Disinfectant. — A  disinfectant  is  a  substance  used  to  destroy  the 
germs  of  infectious  diseases.  The  common  disinfectants  are  formaldehyd  (liquid, 
gaseous),  carbolic  and  (phenol)  cresol,  chlorinated  lime  (chlorid  of  lime),  corrosive 
sublimate.  See  Dorset,  M.:  Some  Common  Disinfectants.  U.  S.  Farmers'  Bull. 
No.  345  (1908). 

Preservation  of  Wood  by  Impregnation. — Impregnation  tends  to  increase  the  dura- 
bility of  wood  by  injecting  an  antiseptic  liquid  and  may  mean  a  desirable,  or  un- 
desirable, change  of  color,  and  in  some  cases  fire-proofing.  Little  is  known  about 
he  latter.     Four  principles  may  be  applied. 

A.  Immersion. 

I.  Immersion  in  a  salt.     Corrosive  sublimate  (kyanizing). 

II.  Metalized  wood  by  dipping  in  a  solution  of  iron  sulphate. 

B.  Boiling. 

I.  In  salt  water  or  solution  of  borax. 

II.  Frank's  mixture,  95  per  cent,  liquid  manure  and  5  per  cent,  of  lime. 

III.  Injection  of  copperas  (siderizing). 

IV.  With  exhaust  steam. 


APPENDICES   III,    IV,   V  693 

C.  Use  of  Hydrostatic  Pressure. — Boucherie  method  with  sulphate  of  copper. 

D.  Use  of  Air  Pressure  (Open-tank  treatment). 

E.  Use  of  Steam  Pressure. — The  liquids  commonly  used  are  chloride  of  zinc, 
coal-tar  creosote,  mixture  of  chloride  of  zinc  and  of  creosote,  gases  of  tar 
oils  (thermo-carbolization),  heavy  petroleums. 

Preservation  of  Wood  by  Air  Drying  or  Kiln  Drying.  Bibliography. — Schenck, 
C.  A.:  Logging,  Lumbering  or  Forest  Utilization,  1913,  and  the  following  bulletins: 
Bureau  of  Forestry  and  late  Forest  Service,  U.  S.  Dept.  Agr.:  No.  41,  Seasoning  of 
Timber;  No.  50,  Cross  Tie  Forms,  Etc.  with  Reference  to  Treated  Timbers;  No.  51, 
Condition  of  Treated  Timbers  Laid  in  Texas,  February,  1902;  No.  78,  Wood  Preser- 
vation in  the  United  States;  No.  84,  Preservative  Treatment  of  Poles;  No.  107, 
Preservation  of  Mine  Timbers;  No.  118,  Prolonging  Life  of  Crossties;  No.  126, 
Preservative  Treatment  of  Red  Oak  and  Hard  Maple  Cross' Ties,  etc. 


APPENDIX  IV 

CULTURE    OF    MUSHROOMS 

Tissue  Culture  of  Fleshy  Fjingi.— Consult  Duggar,  B.  M.:  The  Principles  of 
Mushroom  Growing  and  Mushroom  Spawn  Making.  Bull.  No.  85,  Bureau  of  Plant 
Industry,  1905:  18. 

This  method  is  applicable  to  the  mushroom  and  to  68  other  species  of  fleshy 
fungi  listed  by  Duggar. 

A  young  sporophore  of  Agaricus  campestris  is  taken  and  broken  open  longitudi- 
nally. A  number  of  pieces  are  carefully  removed  with  a  sterile  scalpel  to  a  sterile 
Petri  dish  on  a  number  of  nutrient  media  such  as  bean  pods,  manure  and  leaf  mould. 
From  this  and  numerous  other  similar  tests  it  was  ascertained  that  when  the  mush- 
rooms, from  which  the  pieces  of  tissue  are  taken,  are  young  and  healthy,  there  is 
seldom  an  instance  in  which  growth  does  not  result.  It  was  easily  shown  that  failure 
to  grow  was  generally  due  to  advanced  age  of  the  mushroom  used,  to  an  unfavorable 
medium,  or  to  bacterial  contamination. 


APPENDIX  V 

SYNOPSIS  OF  THE  FAMILIES  AND  PRINCIPAL  GENERA  OF  THE  MYXOGASTRALES 

Suborder  I.  Exosporeae. — Spores  developed  outside  of  the  sporophore. 

Family    I.     Ceratiomyocace^. — Sporophores     membranous,   branched;    spores 
white,  borne   singly   on    filiform   stalks   arising   from    the   areolated 
sporophore. 
Suborder  II.  Endosporea;.— Spores  developed  inside  the  sporangium,  sthalium  or 
plasmodiocarp. 
A.  Spores  violet-brown,  or  purplish  gray  (ferruginous  in  Slcmonitis  fcrruginea 
and  S.flavogenita,  colorless  in  Echinostelium). 
(a)  Sporangium  provided  with  lime  (Calcium  carbonate), 


694  ADDITIONAL   EXERCISES 

Family  2.  Phvsarace^. — Lime  in  the  form  of  minute  round  granules,  innate 
in  the  sporangium  wall. 
Capillitium  charged  with  lime  throughout.     Badhamia. 
Capillitium  of  hyaline  threads  with  lime  knots. 

Sporangia  single,  subglobose,  or  plasmodiocarps;  capillitium  without  free, 

hooked  branches.     Physarum. 
Sporangia  forming  an  sethalium.     Fidigo. 

Plasmodiocarps;  capillitium  with  free,  hooked  branches.     Cienkowskia. 
Sporangia  goblet-shaped  or  ovoid;  stalks  cartilaginous.     Craterium. 
Sporangia  ovoid,  shining,  clustered;  stalks  membranous.     Leocarpus. 
Capillitium  without  lime. 

Sporangial  wall  opaque.     {Chondriodcrnia  (  =  Diderma). 
Sporangial  wall  hyaline.     Diachaa. 
Family  3.  Didymiace^. — ^Lime   in   superficial    crystals    deposited   outside    the 
sporangial  wall. 
Crystals  stellate,  sporangia  single.     Didymium. 

Crystals  stellate,  sporangia  forming  an  sthalium.     Spumaria  (  =  Mucilago). 
Crystals  lenticular.     Lepidoderma. 
(b)  Sporangia  without  lime. 
Family  4.  Stemonitace^. — Sporangia    single,    provided    with    a     stalk    and 
columella. 
*Sporangial  wall  evanescent. 
Capillitium    spreading    from    the  column    and    forming  a  superficial   net. 

Siemonitis. 
Capillitium  as  above,  but  not  forming  a  superficial  net.     Comatrkha. 
Capillitium  spreading  from  the  apex  of  the  sporangium.     Enerthenema. 
**Sporangial  wall  more  or  less  persistent.   . 

Capillitium  radiating  from. the  columella.     Lamprodcma. 
Capillitium  scanty,  colorless,  branching  from  a  short  columella,  sporangia 
very  minute.     Echinostclium. 
Family  5.  Brefeldiace^. — Sporangia  combined  into  an  aethalium. 
Capillitium  irregularly  branched.     Amaurochate. 
Capillitium  with  chambered  vesicles.     Brcfddia. 
B.  Spores  variously  colored,  not  violet  {except  Cribraria  violacea). 

(a)  Capillitium  wanting,  or  not  forming  a  system  of  uniform  threads. 
Family  6.  CribeariacEvE. — Sporangial    wall    membranous,    beset    with    micro- 
scopic round  plasmodic  granules. 
Sporangia  asthalioid,  the  wall  not  forming  a  persistent  net.     Lindbladia. 
Sporangial  wall  forming  persistent  net.     Cribraria. 
Sporangial  wall  forming  numerous  parallel  ribs.     Diclyditim. 
Family  7.  Liceace^. — Sporangial  wall  cartilaginous. 

Sporangia  solitary,  sessile.     Licea. 
Family  8.  Tubiferace^. — Sporangial   wall   membranous,  without   round  plas- 
modic granules. 
Sporangia  tubular  compacted.     {Tuber  if  era  (  =  TuhuUna). 


APPENDICES  V,   VI  695 

Family  9.  Reticulajiiace^.— Sporangia  closely  compacted  and  usually  forming 
an  sethalium,  true  capillitium  none. 
Sporangia    columnar,    inner    walls    reduceri    to    straight    slender    threads. 

Dictydalhalium. 
Sporangia  interwoven,  inner  wall  reduced  to  broad  bands.     Enlcridium. 
Sporangia  interwoven,  inner  walls  laciniated.     Relicularia. 
(b)  Capillitium  present;  a  system  of  uniform  threads. 
Family  10.  Trichiace^. — Sporangia  single,  rarely  in  an  athalium.     Peridium 
without  thickenings,  without  lime.     Capillitium  of  tubular  simple,  or 
branched,  free  threads.     Spore  mass  as  capillitium,  yellow  or  red, 
rarely  white  or  brown,  never  violet. 
*Capillitium  of  free  elaters,  or  an  elastic  network  of  spiral  thickenings. 
Elaters  free,  spirals  distinct.     Trichia. 
Elaters  free,  scanty,  spirals  obscure.     Oligonema. 

Elaters  combined  into  a  web  or  network.     {Hemitrichia  (  =  Hemiarcyria). 
**Capillitium  a  profuse  network  of  threads  (usually  scanty  and  free  in  Peri- 
chana  populina),  thickened  with  cogs,  half  rings,  spines  or  warts. 
Sporangia  stalked,  sporangial  wall  evanescent  above.     Arcyria. 
Sporangia  sessile,  clustered,  the  walls  single,  persistent.     Lachnoholus. 
Sporangia  sessile,  the  walls  usually  double.     Perichana. 
***Capillitium  coiled  and  hairlike,  or  straight,  and  attached  to  the  sporangial 
wall. 
Capillitium  straight.     Dianema. 

Capillitium  penicillate,  spirally  banded.     Prototrichia. 
****Sporangia  forming  an  aethalium;  capillitium  consisting  of  branched  color- 
less tubes. 
Capillitial  tubes,  thick- walled  where  they  traverse  the  cortex,  thin- walled 
among  the  spores.     Lycogala. 

APPENDIX  VI 

KEY  FOR  THE  DETERMINATION  OF  SPECIES  OF  MUCOR 

Laboratory  Work. — The  teacher  will  find  it  good  educational  practice  to  supply 
the  class  with  material  of  the  commoner  moulds  in  order  that  they  may  become 
familiar  with  the  general  morphology  of  the  ZYGOMYCETALES. 

From  the  standpoint  of  taxonomy  the  columella  is  an  organ  of  the  first  im- 
portance. The  position  of  the  columella  in  relation  to  the  wall  of  the  sporangium 
has  been  described  as  "free,"- "subjacent,"  "infundibuliform." 

Terms  which  have  been  applied  in  systematic  works  to  the  different  shapes  of 
the  columella^  are  illustrated  in  Fig.  240,  a  to  /,  inclusive. 

The  spores,  whether  sporangiospores,  conidiospores,  chlamydospores,  oidiospores 
or  stylospores  (as  in  Mortierella),  have  been  described  b)^  special  names,  as  spheric, 
ellipsoidal,  oval,  dumbbell-shaped,  spindle-shaped,  bottle-shaped,  bead-shaped,  etc. 

'Lender,  Dr.  Alf.:  Les  Mucorinees  de  la  Suisse,  1908:  29. 


696 


ADDITIONAL   EXERCISES 


Several  solid  culture  media  recommended  by  Lindner  can  be  used  in  the  growth 
of  various  moulds  in  test-tubes  and  in  Petri  dishes  for  class  use.  Such  is  grape  juice 
exactly  neutralized  and  combined  with  10  per  cent,  gelatin.  Another  medium  is 
prepared  by  taking  i  liter  of  white  wine,  heating  it  over  a  flame  for  one-half  hour  to 
drive  off  completely  the  alcohol.  The  liquid  lost  by  evaporation  is  replaced  to  bring 
the  volume  up  to  i  liter.  It  is  neutralized  exactly  and  10  per  cent,  gelatin  is  added. 
On  this  medium  moulds  grow  luxuriantly.  The  gelatin  can  be  replaced  by  agar- 
agar,  using  1.5  per  cent.,  and  the  advantage  of  this  medium  is  that  it  does  not 
liquefy.  The  writer  has  found  baker's  bread  a  useful  medium  for  the  growth  of 
moulds  under  bell  jars,  the  air  of  which  is  kept  moist  by  filter  paper.  If  the  bread 
is  used  in  Petri  dishes,  it  can  be  sliced,  cut  into  a  circular  form,  soaked  in  water,  or 
beerwort,  placed  under  cover  in  the  Petri  dish,  which  should  then  be  sterilized  one 
or  two  times.  He  has  found  beerwort  agar  extremely  useful  in  raising  moulds  and 
other  filamentous  fungi.     A  supply  of  the  -\-  and  —  races  of  heterothallic  moulds 


Fig.  240. — Forms  of  columella,  a.  Spheric;  b,  spheric  with  collarette;  c,  oval;  d, 
depressed  oval;  e,  piriform;  /,  panduriform;  g,  conic;  h,  cylindro-conic;  i,  mammiform; 
k,  I,  spinescent.      (After  Lendner.) 


should  be  kept  in  culture,  so  that  the  students  may  experiment  with  the  formation 
of  the  gametes  and  zygospores.  These  can  be  mounted  in  acetic  acid  with  a  ring 
of  asphalt  about  the  cover-glass,  or  they  can  be  fixed  and  carried  up  through  the 
alcohols  to  such  materials  as  Venetian  red  in  which  they  are  not  only  beautifully 
stained,  but  also  keep  indefinitely.  The  Venetian  red  can  be  softened  in  a  water 
bath  and  a  little  placed  in  the  center  of  a  slide  with  the  addition  of  a  little  balsam 
to  fill  out  the  space  beneath  the  cover. 

The  systematic  study  of  the  moulds  should  begin  after  their  general  morphology 
and  physiology  have  been  considered.  Cultures,  the  names  of  which  are  known  to 
the  teacher,  should  be  then  given  to  the  members  of  the  class  in  mycology,  as  un« 
known  moulds,  which  the  members  of  the  class  should  mount  and  determine.  Such 
mounts  may  be  made  in  2  per  cent,  acetic  acid  after  treating  first  with  a  weak  alcohol 
(10  per  cent.)  to  wet  the  mycelium,  so  that  the  acetic  acid  will  cover  the  specimen 
without  air  bubbles  and  without  the  hyphae  massing  together,  as  happens  frequently 


APPENDIX  VI  697 

when  acetic  acid  is  applied  without  the  preceding  application  of  the  alcohol.  The 
identification  of  the  "unknown"  moulds  can  be  made  by  the  use  of  the  following 
key,  which  is  a  translation  of  the  one  given  by  Lindner  in  his  work  on  the  Swiss 
moulds,  and  which  includes  most  of  the  important  moulds  of  the  world.  Pure 
cultures  of  various  moulds  can  be  obtained  from  Johanna  Westerdijk,  Director  of 
the  Phytopathological  Laboratory,  Amsterdam,  Holland;  from  Krai's  Bacteriologis- 
chen  Laboratorium,  Prague,  Bohemia,  i.,  Kleiner  Ring,  11;  and  from  Mrs.  Flora 
W.  Patterson,  Bureau  of  Plant  Industry,  Washington,  D.  C.  Some  of  them  can  be 
obtained  by  exposing  various  articles  to  the  air  under  a  bell  jar  with  filter  paper. 
Transfers  of  these  moulds  to  fresh  culture  media  should  be  made  every  two  or  three 
months.  During  the  summer  and  even  during  the  winter  the  cultures  can  be  kept 
on  ice  in  a  refrigerator,  so  that  the  transfers  need  not  be  made  so  frequently  during 
the  hot  weather  of  the  summer,  or  while  the  teacher  is  off  on  his  vacation.  The 
janitor  should  be  instructed  to  look  after  the  ice  supply  during  the  year.  Cf .  Povah, 
A.  H.  W.:  A  Critical  Study  of  certain  Species  ofMucor.  Bull.  Torr.  Bot.  Club, 
44:  241-259,  May,  1917,  continued. 

Key  for  the  Determination  of  Species  of  Mucor 

Sporangiophores  not  branched,     i  Group  Mono-mucor. 
Sporangiophores  branched. 

(a)  Branches  rare,  or  more  numerous  and  indefinite,  in  racemes,  or  corymbs. 

2  group  Racemo-mucor. 
(h)  Branches  definite  in  sympodia.     3  Group  Cymo-mucor. 

I  Group  Mono -Mucor 

Sporangiophores  unbranched.     (E.xceptionally  unless  the  conditions  of  nutrition 
are  unfavorable,  they  form  branches.     These  are  anomalous  cases.) 

1.  Sporangiophores  at  first  erect,  afterwards  weak,  finally  drooping  and  trans- 
formed into  a  woolly  felt  of  a  rusty  color,     i  M.  rufesccns  Fischer. 
Sporangiophores  always  erect  and  forming  a  matted  growth.     (2) 

2.  Sporangiophores  never  exceeding  2  cm.     (3) 
Sporangiophores  longer  than  2  cm.     (7) 

3.  Sporangiophores  never  e.xceeding  300  /j..     (4) 
Sporangiophores  exceeding  o  5  cm.  (maximum  2  cm.).     (5) 

4.  On  solid  media  matted  growth  very  short,  velvety,  color  at  first  brownish 
red-carmine  then  grayish,  sporangia  small  (20;u  maximum).  2  M.  Raman- 
niamus  MoUer. 

Matted  growth  scarcely  visible,  sporangiophores    210^1,  colorless,    septate; 
sporangia  40  to  45^l  diameter.     3  M.  siibtilissimus  Oudemans. 

5.  Wall  of  sporangium  not  diffluent;  on  breaking  it  leaves  an  irregular,  ragged 
collarette,  sporangia  36  to  42yu  diameter,  spores  elliptic  6/x  by  8^.  Matted 
growth  1.5  tall.     4  M.  hygrophiliis  Oudemans. 

Wall  of  sporangium  not  diffluent,  sporangia  large,  80  to  q8;u  in  diameter, 
spores  elliptic  s^u  by  Sju. 


698  ADDITIONAL   EXERCISES 

Matted  growth  2  cm.  high.     5  M.  advcnlitius  Oudemans. 
Columella  with  orange-red  contents;  variety  auranliaca  Lendner. 

6.  Spores  mixed  with  oil  drops  and  intersporal  granular  protoplasm.     6  M. 
plasmaticus  van  Tieghem. 

Without  drops  of  oil  in  the  sporangium.     (7) 

7.  Sporangiophores  2  to  3  cm.  long.     (8) 
Sporangiophores  more  than  3  cm.    (9) 

8.  Sporangia  8om  diameter,  columella  oval,  spores  8^  by  lo^i  (except  8  by  14). 
7  M.  hiemaUs  Wehmer. 

Sporangia  larger  than  250  to  3 50M,  columella  pyriform,  large,  spores  4  to  8m 
by  5  to  13m-     8  M.  piriformis  Plscher. 

9.  Wall  of  sporangium  ruptured  rapidly,  columella  frequently  with  yellow  con- 
tents, spores  3  to  6m  by  6  to  i2m.     9  M.  mucedo  Linn.  (Fig.  13). 

Wall  of  sporangium  ruptured  slowly,  columella  colorless,  spores  very  large, 
ISM  by  30  to  ^^n.     10  M.  mucilagineus  Brefeld. 

2  Group  Racemo-Mucor . 
Branching  indefinite,  in  racemes  or  in  corymbs. 

1.  Branching  secondary  verticillate,  these  last  have  at  their  nodes  the  verticil- 
late  branches.     11  M.  glomerula  Lendner  (Bainier). 

Branching  open  in  racemes,  or  in  corymbs. 

2.  Columella  hemispheric,  covered  with  colorless  threads  resembling  the  capil- 
litium  of  certain  Myxomycetes.     12  M.  comatus  Bainier. 

Columella  round  or  oval,  never  presenting  capillitial  character,     (3) 

3.  Sporangiophore  at  first  erect,  then  curved  toward  the  substratum,  and  then 
fading.     13  M.  de  Baryanus  Schostakowitsch. 

Sporangiophores  always  erect  and  forming  a  matted  growth.     (4) 

4.  Species  parasitic  on  other  Mucorace^.     14  M.  parasiticus  Bainier. 
Species  not  parasitic.     (5) 

5.  Sporangiophores  of  two  kinds,  one  with  a  terminal  large  sporangium  with 
diffluent  wall,  the  others  lateral,  bearing  sporangioles  with  persistent  walls. 
15  M.  agglomeratus  Schostakowitsch. 

Species  not  possessing  the  above  characters.     (6) 

6.  Sporangiophores  bearing  laterally  the  branches  with  normal  sporangia 
(or  abortive),  or  with  zygospores. 

Suspensors  unequal.     (7) 

Sporangiophores  normally  laterally  (i.e.  all  terminated  by  sporangia). 

Zygospores  with  suspensors  approximately  equal.     (8) 

7.  Sporangiophores  straight,  simple  or  branched  bearing  one  or  two  opposite 
branches  terminated  by  sporangia.  Columella  depressed,  spores  elliptic  2  to 
;in  by  4  to  5m.     16  M.  Moelkri  Vuillemin  (Fig.  241). 

Sporangiophores  straight,  branched,  bearing  verticillately  two  to  four 
sporangia,  columella  roundish,  spores  spheric  2  to  2>t^  diameter,  it  M . 
heterogamus  Vuillemin. 


J 


APPENDIX   VI 


699 


Spores  unequal   (mixture  of   numerous  small  spores  with  others  twice  as 

large).     (9) 

Spores  approximately  equal  in  size.     (10) 

Sporangiophores  0.5  to  1.5  cm.,  straight.     Sporangia  80  to  125/1  diameter, 

spores  spheric  or  angular  of  diverse  forms,  4  to  15/^  diameter.     18  M.  heiero- 

sporus  Fischer. 

Sporangiophores  ordinarily  3  to  4  mm.  (i  cm.  maximum),  sporangia  70/x 

diameter  as  maximum.     Spores  oval  or  subcylindric  2  to  6ju  by  6  to  8/x. 

Chlamydospores  along  the  course  of  the  sporangiferous  hyphas.     ig  M. 

sylvaticus  Hagem. 


Fig.   241. — Mucor  Moelleri.     Stages  in  zygospore  formation.      {After  Lendner.) 


Sporangiophores  i  cm.  Sporangia  40  to  54M,   wall  dehiscent.     20  M.  lau- 
sannensis  Lendner. 

10.  Wall  of  sporangium  not  diffluent,  but  breaking  into  pieces.     (11) 
Wall  diffluent.     (13) 

11.  Spores  spheric  7m  diameter.     21  M.  corymbosus  Harz. 
Spores  oval.     (12) 

12    Sporangiophores   frecjuently    unbranched,    chlamydospores   provided    with 

very  fine  points;  azygospore  formation  the  normal  process.     22  M.  tenuis 

Bainier. 

Sporangiophores  branched,  chlamydospores  with  smooth  walls,  zygospores 

and  azygospores.     23  M.  racemosus  Fresenius  (Fig.  30). 
13.  Spores  spheric,  3  to  3. 5m-     24  M.  piisillus  Lindt, 

Spores  oval  or  elongated.     (14) 


700  ADDITIONAL   EXERCISES 

14.  Large  species  6  to  8  cm.  tall  (exceeding  in  all  cases  2  cm.).     (15) 
Small  species  never  exceeding  2  cm.  in  height.     (16) 

15.  Sporangiophores  6  to  7  cm.  in  height,  sporangia  300  to  400/i  (exceptionally 
5oom),  spores  7.5  by  i7.5m-     25  M.  proliferus  Schostakowitsch. 
Sporangiophores  6  to  8  cm.  in  height,  sporangia  140  to    150^   diameter, 
spores  4.2fi  by  9  to  12^.     26  M.  flavus  Bainier. 

16.  Columella  largely  subjacent  and  concrescent  with  the  wall  of  the  sporangium, 
diameter  looyu,  spores  2  to  4^.     27  M.  mollis  Bainier. 

Columella  free  and  slightly  flattened  at  base.     (17) 

17.  Spores  oval,  small  2.1^1  by  4.2/^,  a  grayish-blue.      28  M .  Jragilis  Bainier. 
Spores  elongated  plano-convex,  unequal,  2  to  5yu  by  5  to  ion.     (18) 

18.  Sporangia  never  exceeding  So/x,  zygospores  frequent,  forming  (on  bread) 
special  branches.     29  M.  genevensis  Lendner. 

Sporangia  a  mean  of  80//  frequently  120^1  diameter,  suspensors  bearing  the 
sporangiophores  as  with  M.  racemosus  (Fig.  30).     30  M.  erectus  Bainier. 

3  Group — Cymo-Mucor 

Sporangiophores  branched  in  sympodial  cymes. 

1.  Sporangiophores  of  two  kinds,   the  one  straight  and  bearing  the  normal 
•  spheric  Sporangia,  the  other  creeping,  circinate  branches  sympodial,  bearing 

piriform  sporangia.     31  M.  pirelloidcs   Lendner. 
Sporangiophores  of  a  single  kind.     (2) 

2.  Sporangiophores  circinate.     (3) 
Sporangiophores  straight  not  circinate.     (6) 

3.  Sporangiophores  never  exceeding  i  cm.,  spores  oval,  maximum  length  6/1-  (4) 
Sporangiophores  exceeding  i  cm.  sometimes  3  cm.,  spores  spheric,  lo^i  or 
more.     (5) 

4.  Wall  of  sporangium  brown,  sporangium  frequently  subsessile,  spores  3  to 
4n  by  s  to  6/x  long.     32  M.  circinelloides  van  Tieghem. 

Sporangia  wall  bluish-black,  sporangia  carried  on  long  pedicels,  frequently 
circinate,  spores  4^1  by  5  to  6^.     33  M.  griseo-cyanus  Hagem. 

5.  Sporangiophores  creeping,  Yz  to  2  cm.,  sporangia  black  120  to  2ooju,  spores 
10.5JU  to  I4M  in  diameter.     34  M.  angariensis  Schostakowitsch. 
Sporangiophores  straight  not  circinate,  the  others  short,  freely  branched  and 
circinate,  sporangia  small  6om  (mean),  12/i  (maximum).     41  M.  laniprosporus 
Lendner  (Fig.  242). 

6.  Spores  spheric  or  very  unequal  of  diverse  forms.  35  M.  heterosponis  sibiricits 
Schostakowitsch. 

Spores  spheric  appreciably  equal.     (7) 
Spores  oval.     (12) 

7.  Species  poorly  cultivated  on  grape- juice  gelatin,  forming  on  bread  a  short 
mat  of  2  to  3  mm.,  sporangia  50  to  70/11,  spores  spheric,  5  to  6ju.  36  M. 
Jansseni  Lendner. 

Species  readily  cultivated  on  grape-juice  gelatin,  forming  a  taller  matted 
surface  (i  to  3  cm.).     (8) 


APPENDIX  VI 


701 


8.  Columella  spinescent.     (9) 
Columella  smooth.     (10) 

9.  Sporangiophores  never  exceeding  2  mm.,  sporangia  60  to  8o/u,  spores  smooth 
7  to  8^.     37  M.  spinescens  Lendner. 

Sporangiophores  over   i   cm.   and   more   tall,   spores  frequently  punctate, 
5  to  8m.     38  M.  plumheus  Bonorden. 


Fig.   242. — Mucor  lam  prosper  us.     a,  b,  c.  Columella;  d,  sporangiole;  e,  sporangium; 
/,  branched  sporangiophore.      (After  Lendner.) 


Sporangia   75   to  120/x,  columella  piriform  or  campanulate,  spores  4  to  8m 

diameter.     39  M.  globosus  Fischer. 

Sporangia  ordinarily  smaller  {iion  maximum),  columella  spheric,  oval  or 

campanulate.     Spores  larger  lo^  (mean).     Species  with  sporangioles  near 

the  substratum.     (11) 

Sporangia  70  to  nop  diameter,  sporangioles  not  caducous,  spores  spheric, 

shining,  lo^.     40  M.  spharosporus  Hagem. 

Sporangia  never  exceeding  80  to  90/1,  spores  lo^. 


702  ADDITIONAL   EXERCISES 

Sporangioles  circinate,  caducous,  sporangiophores  more  elevated  than  in 
preceding  species.     41  M.  lamprosporus  Lendner  (Fig.  242). 
Sporangia  60  to  8o/i,  spores  normally  8  to  10,  spheric  or  accompanied  by 
abnormal  spores,  oval  8  to  iom  by  30/i  long,  without  sporangioles.     42  M. 
dimorphosporus  Lendner. 

12.  Large  species  9  to  12  cm.  high.     (13) 
Small  species.     (14) 

13.  Sporangiophores  9  to  10  cm.,  sporangia  up  to  i  mm.  diameter,  spores  10.5 
by  28;u.     43  M.  irkutensis  Schostakowitsch. 

Sporangiophores  10  to  12  cm.,  sporangia  500M,  spores  5;u  by  8.6.     44  M. 
Wasnessenskii  Schostakowitsch. 

14.  Wall  of  sporangia  not  diffluent,  breaking  into  pieces.  45  M.  brevipes  Riess. 
Wall  of  first  sporangia  diffluent.     (15) 

15.  Spores  elongate  with  punctate  spore  walls,  sporangia  blackish,  100^1  diameter. 
46  M.  amhiguus  Vuillemin. 

Spores  subspheric  with  smooth  walls.     (16) 

16.  Species  forming  on  bread  or  grape-j-uice  gelatin  a  mycelium  somewhat 
raised  and  of  a  yellow  color.     47  M.  Rouxianus  Wehmer. 

Species  forming  a  matted  growth  of  i  to  3  cm.  tall.     (17) 

17.  Species  branched  but  little.     (18) 
Species  copiously  branched.     (19) 

18.  Sporangia  50  to  350M,  columella  spheric,  spores  spheric  or  elliptic  or  angular, 
4.2  by  6.SM  with  chlamydospores.     48  M.  geophilus  Oudemans. 
Sporangia  90^1  to  170M  diameter,  columella  ovoid,  spores  subspheric  5  to  6m 
by  6  to  8m  rarely  iom.     49  M.  strictus  Hagem. 

19.  Sporangia  35  to  70M  (90M  diameter),  spores  6m  by  8m  or  8  to  iom  diameter, 
yellow  pigment  in  hyphae  weakly  developed.  50  M.  Prainii  Chodat  & 
Nechitch. 

Sporangia  50M,  wall   more   diffluent,  spores   more  frequently  oval  and  very 
small,  4  to  5m  by  5  to  7m,  also  4  to  7m  diameter.     51  M .  javanicus^  Wehmer. 

APPENDIX  VII 
Keys  for  the  Determination  of  Species  of  Aspergillus  and  Penicillium 

For  student  use  in  systematic  study,  or  identification  of  the  green  moulds  be- 
longing to  the  genus  Aspergillus,  the  teacher  will  find  the  following  key,  adopted 
from  "Household  Bacteriology"  by  the  Buchanans,  pages  76  and  77,  of  great  value. 
Lafar  in  his  "Technical  Mycology,"  Vol.  II,  Part  2,  also  gives  on  page  308  a  useful 
specific  summary.  The  different  species  may  be  kept  in  culture  for  distribution 
as  unknown  to  the  members  of  the  class. 

key  to  common  species  of  ASPERGILLUS 

I.  White  spores,  or  nearly  white. 
A.  Sterigmata  unbranched.     Aspergillus  catididus. 
1  M.  dubius  is  a  variety  of  M.  javanicus. 


APPENDIX  VII  703 

B.  Sterigmata  branched.     Aspergillus  albus. 
II.  Colored  spores. 

A.  Spores  yellowisli-green,  bluish-green,  grayish-green,  green. 

1.  Sterigmata  unbranched. 
(a)Perithecia  produced  readily. 

1.  Perithecia  not  imbedded,  naked.     A.  herbariorum. 

2.  Imbedded  perithecia. 

With  slightly  swollen  conidiophore  tips,  sterigmata  club-shaped,  later- 
ally placed.     A.  clavaius. 

With  hemispheric  conidiophore  tips,  sterigmata  terminal.     A.fumigatus. 
(b)  Perithecia  unknown. 

1.  With  large  conidiophore  tip,  elongate  80  to  ioom  by  500  to  Soo/x.    A. 
giganteus. 

2.  With  smaller  conidiophore,  end  spheric,  or  hemispheric. 
With  rough  worty  conidiophore.     A .  flavus. 

With  smoother  conidiophore.     A.  oryzea. 

2.  Sterigmata  branched. 

(a)  With  rusty-brown  myceUum.     A.  versicolor. 

(b)  Mycelium  not  rusty-brown. 

End  of  conidiophore,  club-shaped  with  lateral  and  terminal  sterigmata. 
A.  pseudoclavatus. 
End  of  conidiophore  hemispheric  with  terminal  sterigmata.     A .  nidulans. 

B.  With  black,  or  dark-brown  conidiospores. 

1.  Sterigmata  unbranched.     A.  calyptratiis. 

2.  Sterigmata  branched.     A.  niger. 

C.  With  reddish-brown,  yellowish-brown,  or  yellow  conidiospores. 
Sterigmata  unbranched,  spores  coffee-brown.     A.  Wenlii. 
Sterigmata  branched,  spores  yellow-brown.     A.  ochraceus. 

The  genus  Penicillium  is  closely  related  to  the  genus  Citroniyces,  which  includes 
fungi  causing  citric  acid  fermentation  in  sugar  media  and  which  has  a  single  whorl 
of  conidia-bearing  cells  (sterigmata)  at  the  tip  of  the  conidiophore.  All  of  the 
fungi  with  the  penicillate  type  of  fructification  are  grouped  together  in  the  form — 
genus  Penicilliiiin.  The  small  and  delicate  conidiophore  differs  from  that  of  Asper- 
gillus in  being  divided  into  a  row  of  short  cells  by  transverse  septae.  The  conidio- 
phores  are  branched  and  the  upright  branches  bear  the  sterigmata  as  tufts  of  termin- 
ally disposed  secondary  branches.  The  conidiospores  are  pinched  off  from  the  ste- 
rigma  and  are  arranged  in  chains.  The  whole  inflorescence  suggests  a  whisk,  or  a 
broom.  The  spores  are  of  various  shapes  and  sizes  from  spheric  to  ellipsoidal. 
Some  have  smooth  walls,  others  are  roughened.  Several  species  show  the  tendency 
to  form  coremia  (coremium),  which  are  tufted  forms  of  inflorescence.  Four,  or 
five,  species  are  known  to  produce  perithecia  and  ascospores,  so  that  no  satisfactory 
key  can  be  based  on  perithecial  and  ascosporic  characters.  The  number  of  species 
which  are  associated  with  the  ripening  of  cheeses,  or  which  produce  decay  in  fruits 
of  various  kinds  is  about  six  or  seven.  The  species  usually  designated  as  Penicillium 
glancnm  and  P.  crustacenm  are  included  in  the  most  recent  paper  by  Thom  under 


704 


ADDITIONAL   EXERCISES 


PeniciUinm  cxpansum  (Fig.  243)  which  can  always  be  obtained  from  apples  decaying 
in  storage.  Colonies  of  this  mould  upon  gelatin  and  potato,  or  bean  agar,  are  green, 
becoming  gray-green  and  later  brown.  The  conidiophores  are  tufted  into  corem- 
ium-like  clusters. 

The  conidia  fructifications  consist  of  one  to  three  main  branches  bearing  verticils 
of  branchlets  supporting  crowded  whorls  of  sterigmata.  Conidiospores  are  elliptic 
2  by  3.3A1,  green,  persisting  in  chains,  when  mounted. 


'*oi;f/'/II 

MM    ;,/ 


Fig.  243. — Penicillium  expansum.  a,  b,  f.  Arrangement  of  branches  of  conidial 
fructification;  c,  d,  e,  conidiiferous  cells  and  chains  of  conidiospores;  g,  h,  j,  k,  I. 
sketches  of  fructification;  m,  n,  o,  germination  of  conidiospores;  r,  s,  sketches  show- 
ing in  ^  loose  aggregations  of  conidiophores,  r  coremmm.      (After  Thorn.) 


Penicillium  Roqiieforli  (Fig.  244)  is  the  agent  in  the  ripening  of  Roquefort, 
Gorgonzola  and  Stilton  cheeses.  Colonies  on  potato  agar  quickly  become  green, 
becoming  a  dirty  brown  when  old.  The  velvety  mycehum  consists  of  radiating 
branching  hyphae  giving  an  indefinite  margin.  The  conidiophores  arise  separately 
and  in  acropetal  succession  from  the  growing  parts  of  submerged  hyphas,  200  to  300M 


APPENDIX  VII 


705 


long  and  septate.  The  conidiospores  are  bluish-green,  globose-cylindric,  4  to  5m  in 
diameter.  Roquefort  cheese  is  a  hard  rennet  cheese  made  from  the  milk  of  sheep. 
Some  imitations  are  made  from  cow's  milk.  The  most  striking  characteristic  of 
this  cheese  is  the  mottled,  or  marbled  appearance  of  the  interior  due  to  the  develop- 
ment of  this  fungus,  which  is  the  principal  ripening  agent.  The  manufacture  of 
Roquefort  cheese  has  been  carried  on  for  at  least  two  centuries  in  the  southeastern 
part  of  France,  in  the  Department  of  Aveyron  and  the  village  of  Roquefort.  The 
curd  is  put  into  hoops,  which  are  filled  in  three  layers,  a  layer  of  bread  crumbs 
penetrated  with  the  hyphje  of  Penicillium  Roquejorli  being  placed  between  the  first 


\m  % 


Fig.  244. — Penicillium  Roqueforti.  a,  part  of  a  conidiop.hore;  h,  c,  other  types 
of  branching;  d,  young  conidiophore,  just  branching;  e, /,  conidiiferous  cells;  g, /j,i, 
diagrams  of  types  of  fructifications;  k,  I,  m,  n,  germinating  spores.      {After  Thorn.) 


and  second  and  the  second  and  third  layers.  The  bread  is  prepared  from  wheat  and 
barley  flour,  with  the  addition  of  whey  and  a  trace  of  vinegar.  It  is  baked  and 
kept  moist  from  a  month  to  six  weeks  during  which  time  it  is  penetrated  by  the 
green  mould  above  mentioned.  For  use  the  bread  is  crumbled  and  sifted.  The 
cheese  is  subjected  to  pressure,  which  is  gradually  increased  for  ten  to  twelve  hours. 
It  is  turned  usually  one  hour  after  putting  into  hoops.  It  is  wrapped  in  cloth  at 
the  end  of  twelve  hours  and  taken  to  the  first  curing  room.  The  cloths  are  fre- 
quently changed  during  ten  to  twelve  days.  Formerly,  the  manufacture  was 
carried  on  by  shepherds  but  now  as  the  industry  is  commercialized,  the  ripening  is 
carried  on  in  caves  in  the  Roquefort  region  in  which  the  air  circulates  freely  and  the 
45 


7o6 


ADDITIONAL   EXERCISES 


temperature  is  40°  to  45°C.     When  ripe,  the  cheeses  are  prepared  for  shipment  by  a 
covering  of  tin-foil  properly  inscribed  with  the  manufacturer's  name. 

Penicillium  Camemherli  (Fig.   245). — The  colonies  of  this  important  fungus  on 
potato  agar  are  at  first  effused  and  white  changing  in  five  to  eight  days  togray- 


FiG.  245. — Penicillium  Camemherli.  a,  Conidiophore  with  common  type  of 
branching  with  conidiospores;  b,  a  common  less-branched  form;  c,  d,  /,  diagrams  of 
large  fructifications;  g,  i,  j,  germinating  conidiospores.  {From  Bull.  82,  Bureau  of 
Animal  Industry,  also  After  Thom.) 


green.  The  hyphae  are  loosely  felted,  about  5m  in  diameter.  The  septate  conid- 
iophores  are  300  to  8oom  in  length  and  3  to  4yu  in  diameter,  thin-walled  often 
collapsing  with  age.  Fructification  about  175^  tall,  consisting  of  one  main  branch 
and  one  lateral  branch,  sparingly  branched  to  produce  the  sterigmata  which  abstrict 
off  ellipsoidal  conidiospores,  smooth  and  bluish-green  by  transmitted  light,  thin- 


APPENDIX  VII 


707 


walled  and  commonly  guttulate,  4.5  to  S-Sm  in  diameter.  The  growing  and  fruiting 
period  is  about  two  weeks.  This  green  mould  grows  in  Camembert  and  other  soft 
cheeses,  where  it  causes  a  breaking  down  of  the  casein.  Camembert  cheese  is  a  soft 
rennet  cheese  made  from  cow's  milk.  A  typic  cheese  is  about  four  and  a  half  inches 
in  diameter  and  one  and  a  quarter  inches  thick,  and  is  sold  in  this  country  wrapped 
in  paper  and  inclosed  in  a  wooden  box  of  the  same  shape.     The  cheese  has  a  rind  of 


Fig.  246. — Penicillium  stoloniferum.  a,  b,  c,  e,  f,  the  types  of  branching  at  the 
tips  of  the  "stolons"  by  which  the  species  spread  in  substrata;  d,  conidial  fructifica- 
tion; h,  j,  k,  I,  sketches  of  conidial  fructifications  of  various  ages;  g,  formation  of 
conidial  spores;  i,  ripe  conidiospores;  m,  n,  germination  of  conidiospores;  o,  rough 
diagram  of  habit.      (After  Thorn.) 


considerable  thickness,  which  consists  of  moulds  and  dried  cheese  surrounding  a 
yellowish,  waxy,  creamy,  or  almost  fluid  interior  depending  upon  the  ripeness  of 
the  cheese.  Probably  originated  about  1791  in  the  Department  of  Orne  in  north- 
western France,  the  industry  has  extended  into  other  departments  of  the  French 
Republic.  It  is  made  from  whole  fresh  milk,  or  from  milk  which  has  been  skimmed 
in  part.  The  curd  which  forms  at  about  8o°to  85°  is  transferred  to  perforated  tin 
forms,  or  hoops.     These  rest  upon  rush  mats,  which  permit  free  drainage.     After 


7o8 


ADDITIONAL   EXERCISES 


draining,  the  cheese  is  frequently  turned  and  in  two  or  three  days,  it  is  carried  to  a 
well-ventilated  room  where  the  ripening  process  begins.  Here  it  remains  fifteen 
to  twenty  days  when  the  surface  becomes  covered  with  Penicillitim  Camemberli, 
which  gradually  breaks  down  the  casein. 


Pig.  247. — Penicillium  iialicum.  a,  b,  c,  d,  e,  f,  g,  types  of  branching  in  verticils 
and  chains  of  conidiospores;  j,  k,  sketches  of  conidial  fructifications;  I,  m,  n,  swelling 
and  germination  of  conidiospores.      (After  Thorn.) 


Penicillium  stoloniferum  (Fig.  246)  grows  on  decaying  fungi,  Boleti,  Polypori  and 
in  cultures  from  milk  and  ensilage.  It  has  been  collected  repeatedly  at  Storrs, 
Conn.,  and  once  upon  decaying  Boletus  scaber  at  the  Jardin  des  Plantes  in  Paris,  and 


APPENDIX  VII 


709 


hence,  it  is  probably  widely  distributed.  Its  stolon-producing  character  is  very 
characteristic  and  diagnostic. 

PenicilUum  italicum  (Fig.  247)  and  P.  olhaceum  occur  on  tropic  fruits,  including 
pineapples,  lemons,  oranges,  etc.  The  fungus  causes  extensive  putrefaction  in  such 
fleshy  fruits  as  the  pineapple. 

PenicilUum  brevicaidc  (Fig.  248)  grows  on  decayed  paper  and  it  has  been  recom- 
mended by  Gosio  for  the  detection  of  arsenic,  since  when  grown  in  media  with  traces 
of  arsenic,  it  forms  the  pungent  compound  diethylarsine.  None  of  the  species  of 
PenicilUum  are  pathogenic.  About  six  to  seven  species  of  this  genus  are  connected 
with  the  ripening  of  cheeses.  For  example,  a  little-known  Norwegian  cheese 
"Gammelost"  has  associated  with  its  ripening,  according  to  Johann  Olsen,  a  green 
mould,  PenicilUum   aromaticum,    and  so  showing  the  unsatisfactory  state  of  our 


Fig.  248. — PenicilUum  brevicaule.  a,  Conidiophores  and  simple  chains  of  conidi- 
ospores;  b,  f,  more  complex  conidial  fructifications;  c,  two  young  chains  of  conidio- 
spores;  d,  e,  echinulate  conidiospores;  g,  h,  j,  sketches  of  forms  and  habits  of  conidial 
fructifications;  k,  germinated  conidiospores.      (After  Thoyn.) 

knowledge  about  these  fungi,  this  fungus  may  prove  on  close  investigation  to  be 
identical  with  the  one  which  works  in  Roquefort  cheese. 

As  all  of  the  species  of  PenicilUum  are  readily  cultivated  and  kept  for  some  time  in 
a  satisfactory  condition  for  study,  they  are  especially  useful  in  the  systematic  exercises 
which  are  essential  in  the  training  of  competent  mycologists.  As  the  time  which  can 
be  devoted  to  such  a  study  is  limited,  the  work  can  be  varied  by  assigning,  as  un- 
knowns, cultures  of  the  different  species  of  the  genus  Aspergillus  to  certain  members 
of  the  class  and  cultures  of  PenicilUum  as  "unknowns"  to  other  members,  and  it  may 
be  advisable  to  interchange  the  material,  so  that  all  of  the  students  in  the  class  in 
mycology  become  acquainted  with  the  similarities,  as  well  as  the  differences  dis- 
played by  fungi  of  the  genera  Aspergillus  and  PenicilUum.  It  is  better  to  distribute 
these  moulds  to  the  class  in  culture  media  in  Petri  dishes  than  in  test-tubes,  because 


7IO 


ADDITIONAL  EXERCISES 


the  removal  of  the  material  for  study  is  more  easily  accomplished,  and  because  the 
whole  growth  can  be  examined  readily  by  placing  the  Petri  dish  on  the  stage  of  the 
microscope  and  examining  with  the  low  power.  In  mounting  such  fungi  for  study 
beneath  a  cover-glass  lo  per  cent,  alcohol  should  be  used  to  wet  the  spores  and 
hyphae,  otherwise  difficulty  will  be  encountered  with  spores  flowing  together  in  mass 
and  the  hyphse  becoming  knotted  together.  Thom,  in  his  paper  on  the  "  Cultural 
Studies  of  Species  of  Penicillium,"  published  as  Bull.  ii8  of  the  U.  S.  Bureau  of 
Animal  Industry  in  19 lo,  recommends  that  the  following  media  be  prepared  for  the 
study  of  the  species  as  his  key  for  the  identification  of  the  species  given  below  is 
based  on  their  behavior  upon  the  recommended  culture  media.  For  this  purpose 
prepare  the  following  media:  (i)  15  per  cent,  gelatin  ("gold  label")  in  distilled  water; 
(2)  15  per  cent,  gelatin  in  distilled  water  plus  3  per  cent,  cane  sugar;  (3)  either  bean 
or  potato  decoction  plus  1.5  per  cent,  cane  sugar;  (4)  bean  or  potato  agar  plus  3 
per  cent,  cane  sugar.     Litmus  solution  may  be  added,  if  desired,  when  cultures  are 


Fig. 


-Penicillium    claviforme.     a,    Coremium    grown    upon    sugar    media; 
coremium  on  gelatin  free  from  sugar.      {After  Thom.) 


made.  Prepare  Petri  dishes  with  10  c.c.  of  each  of  the  media  used  and  allow  them  to 
cool.  Inoculate  two  or  more  Petri  dishes  of  each  medium  with  spores  of  the  species 
to  be  distributed  to  the  class.  Incubate  at  2o°C.  (the  laboratory  temperature  is 
usually  satisfactory).  Have  the  members  of  the  class  examine  at  intervals  of  three 
days,  or  less,  making  naked-eye  observations  from  above  and  below  also  with  a 
hand  lens  and  with  the  low  power  of  the  compound  microscope.  A  drop  of  litmus 
solution  at  the  margin  of  a  colony  can  be  used  to  test  acidity,  or  alkalinity. 

Have  the  class  examine  i  and  2  for  liquefaction;  2  and  4  for  coremium  amd  sclero- 
tium  formation  which  will  call  for  continued  examination  for  at  least  two  weeks. 

Below  will  be  found  two  separate  keys.  One,  after  Thom,  is  a  general  key 
of  species  of  Penicillium  grown  upon  the  above-recommended  agar  and  gelatin 
media.  The  second  key,  after  Buchanan,  which  includes  the  species  of  most  eco- 
nomic importance,  is  based  on  the  character  of  the  substratum  on  which  the 
fungi  are  found  growing  in  a  state  of  nature. 


APPENDIX   VII 


711 


Fig.  250. — Penicillium  Duclauxii.  a,  b,  Conidial  fructifications  with  young 
smooth  conidiospores;  c,  d,  e,  conidial  fructifications  from  potato-agar  plate  culture, 
more  complex  types-;  /,  g,  h,  j,  sketches  of  habit  upon  potato  agar;  k,  ripe  spores 
highly  magnified  to  show  delicate  markings;  I,  m,  n,  germination  of  spores;  si, 
coremium.      (After  Thorn.) 


Fig.  2 si. ^-Penicillium  chrysogenum:  a.  b,  c,  d,  e,  branching  of  conidial  fructifica- 
tion from  gelatin  plates;  /,  g.  h,  j,  I,  m,  sketches  of  conidial  fructifications  from 
potato-agar  plates;  n,  o,  germination  of  conidiospores.      {After  Thorn.) 


712 


ADDITIONAL   EXERCISES 


I.  Key  of  Species  Grown  on  Agar  and  Gelatin  Media 

A.  Species  fruiting  typically  by  coremia  (vertical  and  definite). 
a.  Coremia  long  (3  to  15  mm.). 

1.  Conidial  masses  strictly  terminal,  olive-green,  fragrant.     P.  daviforme 
(Fig.  249). 

2.  Upper  third  of  coremia  fertile,  conidia  green.     P.  Duclauxii  (Fig.  250). 
aa.  Coremia  small. 


Fig.  252. — Penicillium  roseum.  a,  b,  c.  Branching  of  conidial  fructification, 
showing  few  cells  of  each  verticil;  d,  e,  conidiiferous  cell  and  conidiospores;  g,  h,  j,  k, 
sketches  of  ripe  fructification  showing  agglutination  of  conidiospores  into  slimy 
masses.     {After  Thorn.) 


1.  Coremia  definite,  densely  crowded,  colony  orange  below.  P.  granu- 
latmn. 

2.  Coremiform  character  indicated  in  cultures  by  clustering  of  conidio- 
phores,  definite  coremia  only  in  old  cultures,  becoming  large  and  definite 
upon  apples.     P.  expansum  (Fig.  243). 

AA.  Species  not  (or  rarely)  producing  coremia  in  culture. 
B.  Species  constantly  producing  sclerotia,  or  ascigerous  masses. 
b.  Producing  ascigerous  masses,  yellow,  or  reddish.     P.  hUeum. 
bb.  Sclerotia   appearing   as    white   masses   in   old   cultures.     P.  ilaliciim  (Fig. 

l-  247). 
bbb.  Sclerotia   reddish   or  pink,    globose   or   elliptic,   500^  or  less  in  diameter. 


APPENDIX  VII 


713 


Fig.  253. — Penicillium  atranienlosmn.  a,  b,  c,  d,  branching  of  conidial  fructifica- 
tions showing  unequal  length  of  branching;  e,  /,  conidiiferous  cell  and  chain  of  co- 
nidiospores;  g,  h,  j,  sketches  of  conidial  fructifications;  i,  conidiospores;  m,  n,  o,  r, 
germination  of  spores.      {After  Thorn.) 


Fig.  254.— Penicillium  lilacinum.  a,  h,  c,  Short  conidiophores  and  verticils  of 
conidiiferous  cells;  d,  conidiiferous  cell,  solitary  and  sessile;  e,  conidia;/,  g,  h,  sketches 
of  conidial  fructifications.      {After  Thorn.) 


714 


ADDITIONAL   EXERCISES 


BB.  Sclerotia  not   (or  rarely)   produced   (under  special  conditions), 
cultures  (i)  and  (2),  compare  agar  cultures. 

C.  Rapid  liquefiers  (abundant  liquid  in  five  to  twelve  days). 

D.  With  definite,  strong  ammoniacal  odor. 

1.  Yellowish  brown,  spores  rough.     P.  brevicaide  (Fig.  248). 

2.  White  or  cream,  spores  rough.     P.  brevicaide  var.  album. 


Use  gelatin 


Fig.  255. — Penicillium  funiculosutn.  a,  b,  c,  d,  e,  f,  conidial  fructifications  with 
conidiiferous  cells  and  conidiospores;  g,  h,  k,  I,  m,  n,  fructifications  separate  and 
borne  upon  hyphae  and  ropes  of  hypha3;  o,  r,  germination  of  conidiospores.  (After 
Thorn.) 


3.  White  or  cream,  spores  smooth.     P.  brevicaide  var.  glabrum. 
DD.  Without  ammoniacal  odor. 
E.  With  yellow  coloration  of  liquefied  gelatin  (not  of  mycelium  in  reverse). 

1.  Colonies  small,  conidiophores  100  to  150^  in  length.     P.  citrinum. 

2.  Colonies  broadly  spreading,  conidiophores  250  to  300^.     P-  chrysogcnum 
(Fig.  251). 


APPENDIX  VII 


715 


EE.  Without  yellow  color  in  liquefied  gelatin  (or  slight  traces  only). 
e.  Colonies  white  to  pink  or  salmon.     P.  roseiim  (Fig.  252). 
ee.  Colonies  some  shade  of  green. 

/.  Colonies  floccose,  margin  spreading  by  stolons.     P.  stoloniferum  (Fig.  246). 

//.  Colonies   velvety;    surface  growth   of  fruiting  hyphse  only;   conidiophores 

200  to  400^1   long,    with   a  verticil   of   branches;  reverse  and   medium 

darkened  in  sugar  media.     P.  alramcntosum  (Fig.  253). 

CC.  Liquefaction  of  gelatin  none  or  slower  than  ten  to  twelve  days,  or  only  partial. 

G.  Colonies  never  green. 


"=^"=^--.ii 


Fig.  256. — Penicillilun  decumbens.  a,  h,  c,  d,  Conidial  fructification  with  a 
single  verticil  of  conidiiferous  cells;  h,  j,  k,  sketches  of  conidial  fructifications.  (Aftet 
Thojn.) 


g.  Colonies  yellowish-brown,  spores  elliptic.     P.  dlvaricatum. 

gg.  Colonies  white  to  lilac,  slow  liquefier,  fourteen  to  sixteen  days.     P.  lilacinum 
(Fig.  254). 

ggg.  Colonies  floccose  white  or  creamy;  conidiophores  long,  typically  penicillate. 
P.  Camemberti  var.  Rogcri. 
GG.  Colonies  some  shade  of  green. 

H.  Surface  with  hyphae  definitely  in  ropes  or  trailing,  bearing  numerous  conidio- 
phores, as  short  branches,  distinctly  traceable  to  their  origin  in  such 
hyphcc. 

h.  Colonies  usually  red  below  and  reddening  the  substratum. 


7i6 


ADDITIONAL   EXERCISES 


1.  Fruiting  areas  dark  green.     P.  funiculostim  (Fig.  255). 

2.  Fruiting  areas  mixed  yellow  and  green.     P.  pinophilum. 
hh.  Colonies  not  producing  red  color. 


Fig.  257. — Penicillium  biforme.  a,  b,  g.  Branching  of  conidial  fructification; 
c,  d,  e,  f,  conidiiferous  cells  and  conidiospores;  h,  j,  k,  sketches  of  conidial  fructifica- 
tions on  potato  agar;  I,  m,  sketches  of  conidial  fructifications  on  sugar  gelatin;  o,  r> 
germination  of  conidiospores.     {After  Thorn.) 

1.  Colonies  gray,  rarely  greenish,  very  loose  floccose.     P.  intricalum. 

2.  Colonies  gray  to  green,  hyphie  scattered,  creeping.     P.  decumbens  (Fig. 
256). 

HH.  Surface  hyphae  not  in  well-defined  ropes,  nor  trailing. 


APPENDIX  VII 


717 


i.  Surface  hyphae  woven  floccose,  course  of  hyphae  not  traceable. 

1.  Gray-green,  long  conidiophores,  no  odor.     P.  Camemberti  (Fig.  245). 

2.  Gray-green,  shorter  conidiophores,  strong  odor.     P.  biforme  (Fig.  257). 


Fig.  258. — PenicilUum  commune,     a,  b,  c,  d,  e,  Conidial  fructification  with  conidio- 
spores;/,  g,  h,j,  k,  I,  sketches  of  fructifications  in  various  stages.      (After  Thorn.) 


ii.  Surface  growth  at  margin  simple  conidiophores,  in  older  parts  both  floccose 
hyphae  and  conidiophores. 
I.  Gray-greenish,  branching  of  conidiophore  rather   loose,  odor  none  or 
slight.     P.  No.  22. 


7i8 


ADDITIONAL   EXERCISES 


Fig.  259. — Penicillium  spinulosum.  a,  b,  Conidial  fructifications,  consisting  of 
single  Verticils  of  conidiiferous  cells;  c,  conidiiferous  cell  with  chain  of  conidiospores 
(smooth);  d,  f,  ripe  echinulate  conidiospores;  c,  swollen  end  of  conidiophore;  g,  /;, 
sketches  of  conidial  fructifications.      (After  Thorn.) 


Fig.  260. — Penicillium  rubrum.  a,  b,  c,  d,  e.  Whole  conidiophores  and  the 
branching  of  conidial  fructifications;/,  g,  conidiiferous  cells  and  conidiospore  forma- 
tion; h,  j,  sketch  of  habit  of  growth;  m,  diagrammatic  figure  of  a  series  of  conidial 
fructifications.      (After  Thorn.) 


APPENDIX   VII 


719 


2.  Green,  conidial  fructiikations  rather  compact,  odor  definite,  "mouldy." 
P.  commune  (Fig.  258). 
Hi.  Fruiting   surface   velvety   of   simple  conidiophores,  or  conidiophores  borne 

so  close  to  surface  of  subtratum  as  to  appear  simple. 
j.   Conidial  mass  a  dense  column  of  conidial  chains. 

1.  Column  from  a  single  verticil  of  sterigmata.     P.  spimilos'itm  (Fig.  259). 

2.  Column  from  a  verticil  of  branchlets  with  verticillate  cells  and  chains. 
P.  nibrum  (Fig.  260). 

jj.  Elements  of  conidial  fructifications  not  in  a  column. 
k.  Conidiospores  smooth. 

I.  Green,  broadly  spreading,  ripe  conidia  globose,  4  to  5^1.     P.  Roqiicfoiti 
(Fig.  244). 


I  CI 

Fig.  261. — Penicillium  purpurogenum.  a,  h,  c,  Conidial  fructifications;  d,  e,f,  g, 
conidiiferous  cells  and  conidiospores;  h,  j,  k,  I,  m,  sketches  of  whole  fructifications. 
{After  Thorn.) 


2.  Green,  less  spreading,  conidiospores  elliptic,  uredium  commonly  purpled. 
P.  purpHrogcnum  (Fig.  261). 

3.  Gray  or  olive-green,  conidiospores  5  to  7   by   3   to   5/u.      P.  digitalum 
(Fig.  262). 

kk.  Conidiospores  delicately  rugulose.     P.  rugulosum  (Fig.  263). 

2.  Key  of  Species  Determinable  from  Substrata.     (After  Buchanan.) 
Cheese  (Camembert  and  Brie). 

1.  Floccose,  white  unchangeable,  no  odor.     P.  Camemberti  var.  Rogeri. 

2.  Floccose,  white  to  gray-green,  no  odor.     P.  Camemberti  (Fig.  245). 

3.  Powdery,     yellowish-white,     spores     smooth,      ammoniacal     odor.     P. 
brcvicaule  var.  glabnim. 


720 


ADDITIONAL   EXERCISES 


4.  Powdery,  yellowish- white,    spores   tuberculate,   ammoniacal   odor.     P. 
brevicaule  var.  album. 

5.  Forming  yellowish-brown   areas,  spores   rough,    ammoniacal   odor.     P. 
brevicaule  (Fig.  248). 

Cheese  (Roquefort). 

I.  Green  streaks  inside  the  cheese.     P.  Roquejorli  (Fig.  244). 


Fig.  262. — Penicillium  digilalum.  a,  Whole  conidiophore  and_ fructification;  b, 
c,  d,  e,  types  of  branching  and  formation  of  conidiospores;  m,  n,  o,  germination  of 
conidiospores.      {After  Thorn.) 


P.  italicum  (Fig.  247). 
P.  digitatum-olivaceum . 


Citrus  fruits. 

1.  Colonies  of  mould,  blue-green. 

2.  Colonies  of  mould,  olive-green. 
Pomaceous  fruits  (apples,  pears,  etc.). 

I.  Blue-green  colonies  finally  producing 
Polyporaceae  (Boleti,  Polypori,  etc.). 

I.  Colonies  green  (yellowish-green),  spreading  by  stolons.     P.  stolonijerum 
(Fig.  246). 


P.  expansum  (Fig.  243). 


APPENDIX  VIII 


721 


Wood  (pine). 

I.  Producing  orange  to  red  stains  in  pine  wood.    P.  pinophilum. 


Fig.  263. — Penicillium  rugulosutn.  a,  b.  Branching  of  conidiophore;  c,  d,  e, 
conidiiferous  cells  and  conidiospores;  /fully  ripe  conidiospore;  g,  h,  j,  swelling  and 
germination  of  conidiospore;./,  m,  diagram  of  conidial  fructifications.      (After  Thorn.) 


APPENDIX  VIII 


Keys  to  the  Genera  of  the  ERYSiPHACEiE 

(See  Salmon,   Ernest  S.:  A  Monograph  of  the  Erysiphaceae  Mem.  Ton.  Bot. 
Club  IX,  1900.) 

A.  Perithecium  inclosing  only  a  single  ascus. 

(a)  Appendage  simple,  filamentous,  unbranched.     r  Spharolheca. 

(b)  Appendage  dichotomously  branched  at  end.     2  Podosphccra. 

B.  Perithecium  containing  many  asci. 
{a)  Spores  unicellular. 

I.  Perithecia  with  appendages. 

*  Appendages  often  basally  swollen,  never  enlarged  into  a  plate, 
t  Appendage  unrolled  at  the  end,  or  only  slightly  and  irregularly  curled. 
*J  Appendages  simple,  or  only  irregularly  branched. 
§  Appendages  mycelium-like,    unbranched,   or  slightly  irregularly 
branched.     3  Erysiphe. 
§§  Appendages  stiff,  bristly,  radially  arranged,  numerous.     4  Pleoch- 
ceta. 
tX  Appendages  frequently  dichotomously  branched  at  apex.     5  Micro- 
sphara. 
46. 


722  ADDITIONAL   EXERCISES 

tt  Appendages  more  or  less  spirally  coiled  at  the  apex.     6  Uncimila. 
**  Appendages  united  at  the  base  into  a  plate.     7  PhyllacHnia. 
2.  Perithecia  without  appendages,  sessile  or  mycelium.     8  Erysibella. 
(b)   Spores  divided.     9  Saccardia. 

Key  to  the  Species  of  Sph^rotheca  (After  Salmon) 

Brief  Characterization. — Perithecia  subglobose,  ascus  solitary,  eight-spored. 
Appendages  floccose,  brown  or  colorless,  spreading  horizontally  and  often  interwoven 
with  the  mycelium,  simple  or  vaguely  branched,  frequently  obsolete. 

1.  Mycelium  persistent,  thick,  pannose,  forming  dense  patches  of  special  hyphae 
in  which  the  perithecia  are  more  or  less  immersed.     (2) 

Mycelium  without  these  characters.     (4) 

2.  Persistent  mycelium  usually  satiny  and  shining,  white,  sometimes  becoming 
gray,  or  pale  brown.     2  pannosa. 

Persistent  mycelium  dark  brown.     (3) 

3.  Inner  wall  of  perithecium  separating  from  the  outer,  hyphse  of  persistent 
mycelium  very  tortuous.     4  lanestris. 

Inner  wall  not  separating,  hyphas  straighter.     3  mors-iivm. 

4.  Perithecia  60  to  ySju  in  diameter,  ascus  60  to  75  by  42  to  50^1,  inner  wall  of 
perithecium  separating  from  the  outer.     5  phytoptophila. 

Perithecia  50  to  120M  in  diameter,  ascus  45  to  90  by  50  to  72/*;  inner  wall 
scarcely  separating.     (5) 

5.  Cells  of  outer  wall  of  perithecium  10  to  20M  wide,  averaging  15/x.     i  hutmili. 
Cells  20  to  30  (rarely  40) /x  wide,  averaging  25/^.     i  humuli  var.  fuUgnea. 

Key  to  Species  of  Podosph^ra  (After  Salmon) 

Brief  Characterization. — Perithecia  globose,  or  globose-depressed;  ascus  solitary, 
subglobose;  spores  eight.  Appendages  equatorial  or  apical,  branches  simple  and 
straight,  or  swollen  and  knob-shaped;  very  rarely  of  two  kinds:  one  set  apical, 
brown,  rigid,  unbranched  or  rarely  one  to  two  times  dichotomous  at  the  apex;  the 
other  set  basal,  short,  flexuous,  simple,  or  vaguely  branched,  frequently  obsolete. 

1.  Basal    appendages    present,    apical    appendages    usually    unbranched.     4 
leiicotricha. 

Basal  appendages  absent.     (2) 

2.  Appendages  erecto-fasciculate,   springing  from  near  the  apex  of  the    peri- 
thecium.    (3) 

Appendages  more  or  less  spreading  and  equatorially  inserted.     (4) 

3.  Appendages  six  to  twelve  and  one-half  times  the  diameter  of  the  perithecium, 
colorless,  or  occasionally  pale  brown  toward  the  base.     2.  Schlectendalii. 
Appendages  one  to  eight  times  the  diameter  of  the  perithecium,  dark  brown 
for  more  than  half  their  length,     i  oxyacantha  var.  tridactyla. 

4.  Appendages  colorless,  or  faintly  tinged  with  brown  at  the  base,  branches  of 
apex  not  swollen.     3  biuncinata. 


APPENDIX  VIII  •  723 

Appendages  dark  brown  for  more  than  half  their  length,  ultimate  branches 
of  the  apex  knob-shaped,     i  oxyacantluc. 

Key  to  Species  of  Erysiphe  (After  Salmon) 

Brief  Characterization. — Perithecia  globose,  or  globose-depressed,  sometimes  be- 
coming concave;  asci  several,  two-  to  eight-spored.  Appendages  floccose,  simple 
or  irregularly  branched  (never  with  a  definite  apical  branching)  sometimes  obsolete, 
usually  more  or  less  similar  to  the  mycelium  and  interwoven  with  it,  very  rarely 
{E.  tortilis)  brown,  assurgent  and  fasciculate. 

1.  Asci  (of  mature  perithecia)  not  containing  spores  on  living  host  plant.     (2) 
Asci  (of  mature  perithecia)  containing  spores. 

2.  Perithecia  large,  135  to  280^  in  diameter,  averaging  200/x,  more  or  less  im- 
mersed in  the  lanuginose  persistent  mycelium.     4  graminis. 

Perithecia  smaller,  80  to  140M,  not  immersed  in  the  lanuginose  mycelium.     (3) 

3.  Haustoria  lobed.     3  galea psidis. 
Haustoria  not  lobed.     2  cichoracearum. 

4.  Asci  two-spored,  rarely  (and  never  uniformly)  three-spored.     (5) 

Asci  three-  to  eight-spored,  rarely  (and  never  uniformly)  two-spored. .   (8) 

5.  Perithecia  52  to  6oju  in  diameter;  asci  three,  48  to  50  by  28  to  36/i.     8  trina. 
Perithecia  80  to  240^  in  diameter;  asci  more  than  three,  larger.     (6) 

6.  Perithecia  large,  becoming  pezizoid,  135  to  240^1  in  diameter,  usually  about 
2oo/u;  asci  seven  to  thirty-eight,  usually  about  twenty,  75  to  iiom  long, 
averaging  gofi,  spores  28  to  40/i»long,  averaging  32  by  i8^i  long.  6  taurica. 
Perithecia  80  to  140/i  (very  rarely  100  to  175);  asci  four  to  twenty-five  (very 
rarely  as  many  as  thirty-six),  usually  ten  to  fifteen,  58  to  goti  long;  spores 
20  to  28/i  long,  averaging  34  by  i4ju.     (7) 

7.  Haustoria  lobed.     3  galeopsidis. 
Haustoria  not  lobed.     2  cichoracearum. 

8.  Perithecia  65  to  i8om  in  diameter,  usually  about  90^1;  asci  usually  few,  two 
to  eight,  rarely  as  many  as  twenty-two,  46  to  72  (rarely  80)  ju  long.     (9) 
Perithecia  larger,  130  to  280M  in  diameter,  averaging  180  to  200/*;  asci,  nine 
to  forty-two,  70  to  11  5m  long. 

9.  Appendages  very  long,  ten  to  twenty  times  the  diameter  of  the  perithecium, 
assurgent  and  fasciculate.     5  tortilis. 

Appendages  long  or  short,  spreading  horizontally,  often  interwoven  with  the 
mycelium,     i  polygoni. 

10.  Perithecia  more  or  less  immersed  in   the  lanuginose  persistent  mycelium. 
4  graminis. 

Perithecia  not  immersed  in  a  lanuginose  persistent  mycelium.     (11) 

11.  Spores  four  to  six,  20  to  22  by  10  to  i2iu.     i  polygoni  var.  sepuUa. 

Spores  eight,  rarely  six  or  seven,  somewhat  roundish,  16  to  20  by  10  to  is/x. 
7  aggregata. 


724  ADDITIONAL   EXERCISES 

Key  to  Species  of  Microsph^ra  (After  Salmon) 

Brief  Characterization. — Perithecia  globose  to  globose-depressed;  asci  several, 
two-  to  eight-spored.  Appendages  not  interwoven  with  the  mycelium,  branched 
in  a  definite  manner  at  the  apex,  which  is  usually  several  times  dichotomously 
divided,  and  often  very  ornate,  rarely  {M.  astragali)  undivided,  or  once  dichotomous 

1.  Asci  two-spored,  appendages  densely  crowded,  flaccid,  about  equalling  the 
diameter  of  the  perithecium.     6  Mougeottii. 

Asci  more  than  two-spored.     (2) 

2.  Appendages  two  and  one-half  to  seven  times  the  diameter  of  the  perithecium, 
usually  much  contorted  and  angularly  bent,  apical  branching  very  irregular 
and  lax,  with  the  branches  very  flexuous  and  more  or  less  curled.  9  euphorbia. 
Appendages  long  or  short  without  the  above  characters.     (3) 

3.  Tips  of  some  or  all  of  the  ultimate  branches  of  the  appendages  recurved.  (4) 
Tips  not  recurved.     (11) 

4.  Appendages  eight  to  twelve  times  the  diameter  of  the  perithecium.  10 
Guarinonii. 

Appendages  less  than  eight  times  the  diameter  of  the  perithecium.     (5) 

5.  Appendages  long  and  flaccid.     (6) 

Appendages  short,  not  exceeding  two  and  one-half  times  the  diameter  of  the 
perithecium,  not  flaccid.     (8) 

6.  Apex  of  appendages  much  branched,  branching  ornate,  more  or  less  close 
spores  22  to  26  by  12  to  iS/x.     4  alni  var.  extensa. 

Apex  less  branched,  more  or  less  widely, forked,  or  branching  close  and  simple, 
spores  18  to  23  by  9  to  13M.     (7) 

7.  Appendages  usually  three  and  one-half,  not  exceeding  five  and  one-half  times 
the  diameter  of  the  perithecium,  asci  three  to  seven,  ovate-globose,  38  to 
48ju  long.     4  alni  var.  divaricata. 

Appendages  two  and  one-half  to  eight  times  the  diameter  of  the  perithecium, 
asci  two  to  sixteen,  ovate-oblong,  45  to  72/i  long.     4  alni  var.  vaccinii. 

8.  Appendages  more  or  less  contorted,  apical  branching  very  lax  and  irregular. 
4  alni  var.  liidens. 

Appendages  not  contorted,  apical  branching  closer  and  regular.     (9) 

9.  Tips  of  the  ultimate  branches  of  the  appendages  not  all  regularly  and  dis- 
tinctly recurved.     4  alni  var.  lonicera. 

Tips  all  regularly  and  distinctly  recurved.     (10) 

10.  Axis  pf  some  of  the  appendages  not  dividing  dichotomously  at  the  apex,  but 
bearing  sets  of  opposite  branches.      4  alni  var.  calocladophora. 
Appendages  regularly  dichotomous  at  apex.     4  alni. 

11.  Appendages  three  to  seven  times  the  diameter  of  the  perithecium,  colored 
nearly  to  apex.     8  Russdlii. 

Appendages  colorless.     (12) 

12.  Appendages  long  and  penicillate.     (13) 
Appendages  not  penicillate.     (15) 


APPENDIX  VIII  725 

13.  Apex  of  appendages  often  undivided,  or  irregularly  one  to  two  times  dichotom- 
ous.     3  aslragali. 

Apex  more  divided.     (14) 

14.  Appendages  four  to  six  times  the  diameter  of  the  perithecium,  branching 
diffuse  and  irregular.     13  Bdumleri. 

Appendages  two  and  one-half  to  five  and  one-half  times  the  diameter  of  the 
perithecium,  apex  more  divided,  branching  closer.     2  euonymi. 
1$.  Branching  of  the  appendages  lax,  irregular.     (16) 
Branching  closer  and  regular.     (17) 

16.  Appendages  two  to  four  times  the  diameter  of  the  perithecium,  not  contorted, 
ultimate  branches  long,  forming  a  narrow  fork.     7  dijfusa. 

Appendages  one  to  two  times  the  diameter  of  the  perithecium,  more  or  less 
contorted,  branching  more  irregular,  with  short  ultimate  branches.  4  ahii 
var.  ludens. 

17.  Apex  of  appendages  with  very  short  primary  and  secondary  branches  more  or 
less  digitate.     5  grossiilaria. 

18.  Apex  with  short,  widely  spreading,  usually  curved  ultimate  branches.  4  alni 
var.  lonicerce. 

Apex  with  long,  straight  ultimate  branches,  not  widely  spreading,  i  berberi- 
dis. 

Key  to  the  Species  of  Uncinula 

Brief  Characterization. — Perithecia  globose  to  globose-depressed;  asci  several, 
two-  to  eight-spored;  appendages  simple,  or  rarely  (U.  aceris)  once  or  twice 
dichotomously  forked,  uncinate  at  the  apex,  usually  colorless,  rarely  dark 
brown  at  base  or  throughout. 

1.  Appendages  colored.     (2) 
Appendages  colorless.     (3) 

2.  Appendages  colored  for  half  their  length  or  more.     5  necator. 
Appendages  colored  only  at  base  (up  to  first  septum).     16  australiana. 

3.  Asci  two-  to  three-spored.     (4) 
Asci  four-  to  eight-spored.     (6) 

4.  Asci  more  than  thirty,  perithecia  very  large,  215  to  320;u  in  diameter.  12. 
polychce-ta. 

Asci  four  to  twenty,  perithecia  85  to  165^  in  diameter.     (5) 

5.  Appendages,  nine  to  twenty-five,  perithecia  average  95^  in  diameter,  asci 
three  to  six.     4  clandestina. 

Appendages  fifty  to  one  hundred  and  thirty,  perithecia  average  130^,  asci 
eight  to  twenty.     8  macrospora. 

6.  Appendages  all  simple.     (7) 
Appendages  some  or  all  branched.     (20) 

7.  Appendages  delicate,  narrow,  3  to  4^1  wide,  asci  four-  to  seven-spored.     (8) 
Appendages  stouter,  wider,  or  if  narrow  with  asci  eight-spored.     (10) 

8.  Asci  about  twenty-five,  perithecia  150  to  200/1  diameter.     13  conjtisa. 
Asci  five  to  eight,  perithecia  86  to  12 2m  in  diameter.     (9) 


726  ADDITIONAL  EXERCISES 

9.  Appendages  fifty  to  one  hundred  and  sixty,  one-half  to  three-fourths  diameter 
of  perithecium.     7  parviila. 

Appendages  twenty-four  to    forty-six,   one    and    one-fourth  to  two  times, 
diameter  of  perithecium,  often  geniculate.     11  geniculala. 

10.  Appendages  stout,  7  to  8^  wide  near  the  base.     (11) 
Appendages  narrower  near  the  base.     (12) 

11.  Appendages  very  few,  six  to  twelve,  enlarged  upward.     15  Delavay's. 
Appendages  crowded,  twenty  to  thirty-six,  scarcely  or  not  at  all  enlarged 
upward.     18  Sengokui. 

12.  Appendages  abruptly  flexuose,  or  angularly  bent.     (13) 
Appendages  straight.     (14) 

*  13.  Appendages  about  equalling  diameter  of  perithecium,  flexuose  above,  not 
angularly  bent,  spores  usually  eight.     9  flexuosa. 

Appendages  one  to  two,  usually  one  and  one-half  to  two  times  diameter  of 
perithecium,  more  or  less  angularly  bent,  spores  four  to  six,  rarely  seven. 

1  solids  var.  Miyabci. 

14.  Appendages  thick- walled,  refractive,  or  rough  at  base.     (15) 
Appendages  thin-walled  throughout.     (17) 

15.  Mycelium  persistent,  densely  compacted,  perithecia  158  to  268ju  in  diameter. 

2  aceris  var.  Tulasnei. 

Mycelium  evanescent,  or  subpersistent,  perithecia  64  to  146;^  in  diameter.     ( 1 6) 

16.  Asci  ovate  or  elliptic-oblong,  24  to  30^  wide,  spores  16  to  20  by  8  to  lo/x. 

3  prunastri. 

Asci  broadly  ovate  to  subglobose,  34  to  40/i  wide,  spores  20  to  25/1  by  10  to 
I3^^.     10  CUntonii. 

17.  Asci  four-  to  six-spored.     i  salicis. 
Asci  seven-  to  eight-spored.     (18) 

18.  Perithecia  168  to  224/x  in  diameter,  appendages  not  exceeding  diameter  of 
perithecium.     6  circinata. 

Perithecia  76  to  138/i  in  diameter,  appendages  one  and  one-fourth  to  two  and 
one-half  times  diameter  of  perithecium.     (19) 

19.  Perithecium  120  to  138^  in  diameter,  appendages  thirty-five  to  sixty,  myce- 
lium persistent,  more  or  less  densely  compacted.     14  aiislralis. 
Perithecia  76  to  105^  in  diameter,  appendages  ten  to  twenty-eight,  mycelium 
evanescent.     17  fraxitiis. 

20.  Mycelium   densely   compacted,   appendages   mostly   simple.     2   accrls   var. 
Tulasnei. 

Mycelium  not  densely  compacted,  appendages  all  or  nearly  all  branched. 
2  aceris. 

APPENDIX  IX 

Collection  and  Preservation  of  the  Fleshy  Fungi. — In  the  collection  of  the  higher 
fungi,  it  is  of  the  utmost  importance  that  certain  precautions  be  employed  in  ob- 
taining all  parts  of  the  plant,  and  furthermore  that  care  be  exercised  in  handling  in 
order  not  to  remove  or  efface  delicate  characters.     Not  only  is  it  important  for  the 


APPENDIX   DC  727 

beginner,  but  in  many  instances  an  expert  may  not  be  able  to  determine  a  specimen 
which  may  have  lost  what  undoubtedly  seems  to  some,  trivial  marks.  The  sug- 
gestions given  here  should  enable  one  to  collect  specimens  in  such  a  way  as  to  pro- 
tect these  characters  while  fresh,  to  make  notes  of  the  important  evanescent  char- 
acters and  to  dry  and  preserve  them  properly  for  future  study.  For  collecting  a 
number  of  specimens  under  a  variety  of  conditions  the  following  list  of  things  is 
recommended. 

Implements. — One  or  two  oblong  or  rectangular  hand  baskets,  capacity  8  to 
12  quarts. 

One  rectangular  zinc  case  with  a  closely  fitting  top  (not  the  ordinary  botanic 
case). 

Half  a  dozen  or  so  tall  pasteboard  bo.xes,  or  tins,  3  by  3,  or  4  by  4,  by  5  inches 
deep,  to  hold  certain  species  in  an  upright  position. 

A  quantity  of  tissue  paper  cut  8  by  10,  or  6  by  8  inches.  Small  quantity  of  waxed 
tissue  paper  for  wrapping  viscid  or  sticky  plants. 

Trowel,  a  stout  knife,  a  memorandum  pad  and  pencil. 

In  gathering  specimens,  care  should  be  taken  to  avoid  leaving  finger  marks  where 
the  surface  of  the  stem,  or  cap,  is  covered  with  a  soft  and  delicate  outer  coat.  Also 
a  little  careless  handling  will  remove  such  important  characters  as  a  frail  volva,  or 
annubus,  which  are  absolutely  necessary  to  recognize  in  a  species.  Having  collected 
the  plants  they  should  be  placed  properly  in  the  basket,  or  collection  case.  Those 
which  are  quite  firm,  and  not  long  and  slender  can  be  wrapped  with  tissue  paper 
(waxed  if  the  specimen  is  sticky),  and  placed  directly  in  the  basket  with  some 
note  or  number  to  indicate  habitat,  or  other  peculiarity,  which  it  is  desirable  to 
make  at  the  time  of  collection.  The  smaller,  more  slender  and  fragile  specimens 
can  be  wrapped  in  tissue  paper  made  in  the  form  of  a  narrow  funnel  and  the  ends 
then  twisted.  The  specimens  should  be  placed  in  the  basket,  or  case,  in  such  a  way 
as  to  prevent  jostling  with  the  gill  surfaces  downward  so  that  any  loose  sand,  or 
other  material  shall  not  fall  between  the  gills  where  it  is  dilScult  to  remove  such 
gritty  substances. 

Field  Notes.- — The  field  notes  should  include  data  on  the  place  where  the  fleshy 
fungi  grew,  the  kind  and  character  of  the  soil,  in  open  field,  roadside,  grove,  woods, 
on  ground,  leaves,  sticks,  stumps,  trunks,  rotting  wood,  or  on  living  trees,  etc. 

Sorting.- — This  should  be  done  in  a  room  with  plenty  of  table  room.  This  sort- 
ing should  be  done  at  once  as  some  forms  deliquesce  rapidly,  others  are  attacked  by 
insects,  while  others  dry  rapidly,  so  as  to  lose  their  shape  and  evanescent  characters. 
Specimens  to  be  photographed  should  be  attended  to  at  once.  Some  of  the  speci- 
mens can  be  kept  for  spore  prints,  others  must  be  preserved  for  the  herbarium. 

Drying  Method. — Frequently  the  smaller  specimens  will  dry  well  when  left  in  the 
room,  especially  in  dry  weather,  or  better,  if  they  are  placed  where  there  is  a  draft 
of  air.  Some  dry  them  in  the  sun.  The  most  approved  method  is  by  artificial 
heat.     Two  methods  are  applicable. 

I.  A  tin  oven  2  by  2  feet  and  2  to  several  feet  high  with  one  side  hinged  as  a  door, 

^  Consult  Atkinson,  George  F.:  Mushrooms,  Edible  and  Poisonous,  Etc., 
Chapter  XVH. 


728  ADDITIONAL  EXERCISES 

and  with  several  movable  shelves  of  perforated  tin,  or  of  wire  netting;  a  vent  at  the 
top  and  "perforations  around  the  sides  at  the  bottom  to  admit  air.  The  object  of 
such  an  oven  is  to  provide  for  a  constant  current  of  air  from  below  upward  between 
the  specimens.  This  may  be  heated,  if  not  too  large,  with  a  lamp,  though  an  oil 
stove,  gas  jet,  or  heater,  is  better.  The  specimens  are  placed  on  the  shelves 
with  the  accompanying  notes  or  numbers. 

2.  An  old  cook  stove  can  be  used  with  wire  screens  3  by  4  feet,  one  above  the  other, 
placed  over  it.  Large  numbers  of  fleshy  toadstools  can  be  dried  on  such  frames. 
A  more  approved  drying  oven  would  be  the  revolving  gas  oven  manufactured  by 
G.  S.  Blodgett,  Burlington,  Vermont. 

"When  the  plants  are  dried,  they  become  brittle  but  if  exposed  to  the  air  a  good 
many  kinds  absorb  moisture  from  the  air  so  that  they  become  pliant  and  can  be 
pressed  flat,  so  as  not  to  crush  the  gills  and  placed  in  paper  envelopes  for  mounting 
on  the  herbarium  sheets. 

When  placed  in  herbarium  they  should  be  poisoned  with  a  saturated  solution  of 
alcohol  and  corrosive  sublimate  to  which  a  spoonful  of  liquid  carbolic  acid  is  added. 
They  should  then  be  air-dried. 

Some  of  the  specimens  when  there  are  a  number  of  duplicates  can  be  placed  in 
museum  jars  in  75  per  cent,  alcohol. 

A  solution  of  strychnine  can  be  used  for  poisoning  fleshy  fungi. 

Sulfate  of  strychnine,  3^8  ounce. 
Warm  water,  4  or  5  ounces. 

Alcohol,  2  ounces. 

Paper  for  Spore  Prints. — For  the  identification  of  many  species  of  fleshy  fungi 
it  is  necessary  to  make  spore  prints.  This  is  best  done  by  breaking  off  the  stipe,  if 
present,  close  to  the  under  surface  of  the  cap,  or  pileus,  and  then  placing  the  cap 
gills  down  on  black  and  white  paper  placed  side  by  side.  Half  of  the  gill  surface 
should  rest  on  the  black  paper  and  half  on  the  white  paper,  so  that  if  the  spores  are 
white,  they  will  make  an  impression  on  the  black  paper,  and  if  dark-colored,  they 
will  leave  an  imprint  on  the  white  paper. 

In  all  cases  where  a  spore  print  is  made  the  plant  should  be  covered  with  a  bell 
glass  to  exclude  currents  of  air.  Such  unprepared  paper  will  save  time  in  the 
identification.  Where,  however,  it  is  desired  to  obtain  fancy  spore  prints,  perfect 
caps  must  be  cut  from  the  stipe  and  placed  gill  downward  on  paper  prepared  with 
some  gum  arable,  or  similar  adhesive  substance,  while  the  paper  is  still  moist  with 
the  fixative,  so  as  to  glue  the  spores  as  they  fall  to  the  surface  of  the  paper.  The 
specimens  should  then  be  covered  by  a  bell  jar  as  previously  directed. 

Good  spore  prints,  thus  obtained,  can  be  used  for  class  demonstrations  by  mount- 
ing between  a  piece  of  heavy  photographic  cardboard  and  a  piece  of  glass.  It  is 
easy  to  passepartout  the  glass  and  the  paper  as  a  museum  specimen. 

Blank  for  Nole-taking. 

No. Locality  

Date  ■ '■ Name  of  collector — 

Weather 


APPENDICES   IX,   X  729 

Habitat. — If  on  ground,  low  or  high,  wet  or  dry;  kind  of  soil;  on  fallen  leaves, 
twigs,  branches,  logs,  stumps,  roots,  whether  dead  or  living.  Kind  of  tree;  in  open 
fields,  pastures,  etc.,  woods,  groves,  etc.  Mixed  woods  or  evergreen,  oak,  chestnut, 
etc. 

Plants. — Whether  solitary,  clustered,  tufted,  whether  rooting  or  not,  taste, 
odor,  color  when  bruised  or  cut,  and  if  change  in  color  takes  place  after  exposure 
to  air. 

Cap. — Whether  dry,  moist,  watery  in  appearance  (hygrophanous)  slimy,  viscid, 
glutinous;  color  when  young,  when  old;  whether  free  from  the  cuticle  and  easily 
rubbed  off.     Shape  of  cap. 

Margin  of  Cap. — Whether  straight  or  incurved  when  young;  whether  striate,  or 
not,  when  moist. 

Stem. — Whether  slimy,  viscid,  glutinous,  kind  of  scales,  if  not  smooth,  whether 
striate,  dotted,  granular  color;  when  there  are  several  specimens  test  one  to  see  if  it 
is  easily  broken  out  from  the  cap,  also  to  see  if  it  is  fibrous,  or  fleshy,  or  cartilaginous 
(firm  on  the  outside,  partly  snapping  and  partly  tough).     Shape  of  the  stem. 

Gills  or  Tubes. — Color  when  young,  old,  color  when  bruised,  and  if  color  changes 
whether  soft,  waxy,  brittle,  or  tough;  sharp  or  blunt,  plane  or  serrate  edge. 

Alilk. — Color  if  present,  changing  after  exposure,  taste. 

Veil  (Inner  veil). — Whether  present  or  not,  character,  whether  arachnoid,  and 
if  so  whether  free  from  cuticle  of  pileus  or  attached  only  to  the  edge;  whether  fragile, 
persistent,  disappearing,  slimy,  etc.,  movable,  etc. 

Volva. — Present  or  absent,  persistent  or  disappearing,  whether  it  splits  at  apex 
or  is  circumscribed,  or  all  crumbly  and  granular  or  floccose,  whether  the  part  on 
the  pileus  forms  warts,  and  then  the  kind,  distribution,  shape,  persistence,  etc. 

Ring. — Present  or  absent,  fragile,  or  persistent,  whether  movable,  viscid,  etc. 

Spores. — Color  when  caught  on  paper. 

Estimation  of  Spore  Numbers. — Paper  containing  spores  is  placed  in  distilled 
water.  The  whole  is  stirred  vigorously  until  the  spores  have  been  washed  off  the 
paper.  A  Leitz  counting  apparatus  is  then  employed  and  the  number  of  spores 
per  square  is  counted.  Another  method  is  to  count  spores  of  Coprinus  comatus,  for 
example  in  situ.     For  details  see  Buller,  Researches  on  Fungi,  p.  82. 

APPENDIX  X 

List  of  Keys  to  Fleshy  Fungi  and  Selected  Keys  of  Fleshy  Fungi 

This  list  includes  the  common  accessible  keys  which  beginners,  amateurs  and 
students  will  find  useful  in  the  determination  of  all  the  conspicuous  fungi.     The 
list  is  taken  from  the  Mj'cological  Bulletin,  Vol.  Ill:  174;  178-179;  182-183;  185- 
186,  edited  by  W.  A.  Kellerman. 
Amanita.    Lloyd:  Volvae  of  U.  S.,  3,  4,  5,  6,  1898. 

McIlvaine:  One  Thousand  American  Fungi,  6,  1900. 

Morgan:  Journ.  Mycol.,  3:  25,  March,  1887. 

Peck:  Rep.  N.  Y.  State  Mus.,  23:  68,  1873;  33:  40,  1880;  48:  310,  1895. 
Amanitopsis.     Beardslee:  Notes  on  the  Amanitas  of  So.  Appalachians,  Part  I, 
Lloyd  Library,  September,  1902. 


730  ADDITIONAL   EXERCISES 

Lloyd:  Volvac  of  the  U.  S.,  8,  9,  1895. 
Agaricus.     McIlvaine:  One  Thousand  American  Fungi,  332,  1900. 

Peck:  Rep.  N.  Y.  State  Mus.,  48:  231,  1895. 
Armillaria.     Peck:  Rep.  N.  Y.  State  Mus.,  43:  41,  44,  1890. 
Boletinus.     NinA  L.  Marshall:  Mushroom  Book,  44,  102,  1901. 
Boletus.     McIlvaine:  One  Thousand  American  Fungi,  406,  421,  423,  430,  436, 
438,  444,  453,  459,  471,  1900. 
Peck:  Rep.  N.  Y.  State  Mus.,  23:  127,  1873;  2>T-  58,  1884;  48:  292,  1895. 
Bull.  N.  Y.  State  Mus.,  i:  58,  May,  1887;  2:  82,  83,  106,  114,  123,  131,  138, 

145,  151,  "September,  1889. 

Bovista.    Lloyd:  Myc.  Notes,  12:  114,  December,  1902. 
Bovistella.    Lloyd:  Myc.  Notes,  23,  1906. 
Catastoma.     Kellerman:  Journ.  Mycol.,  9:  239. 

Lloyd:  Myc.  Notes,  (214),  13:  121,  February,  1903. 
Cantharellus.     Peck:  Rep.  N.  Y.  State  Mus.,  23:  121,  1873;  37:  35,  1884.     Bull. 

N.  Y.  State  Mus.,  i:  35,  May,  1887. 
Claudopus.     McIlvaine:  One  Thousand  American  Fungi,  266,  1900. 

Peck:  Rep.  N.  Y.  State  Mus.,  39:  67,  1886. 
Clavaria.     McIlvaine:  One  Thousand  American  Fungi,  513,  1900. 

Peck:  Rep.  N.  Y.  State  Mus.,  24:  104,  1873. 
Clitocybe.     Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  6:  67,  1883. 

Peckk  Rep.  N.  Y.  State  Mus.,  23:  76,  1873;  48:  270,  1895. 
Clitopilus.     Beardslee:  Journ.   Mycol.,   11:   109,  May,   1905.     Mycol.   Bull.,   3: 

146,  1905. 

Peck:  Rep.  N.  Y.  State  Mus.,  42:  40,  1889. 
CoUybia.    Lloyd:  Mycol.  Notes,  34,  37,  41,  December,  1900. 

Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  6:  70,  1883. 

Peck:  Rep.  N.  Y.  State  Mus.,  23:  78,  1873. 
Coprinus.     Peck:  Rep.  N.  Y.  State  Mus.,  23:'  103,  1873;  48:  241,  1895. 

Massee,  G.:  Annals  of  Botany,  X:  123-184,  1896. 
Cortinarius.     Earle:  Torreya,  2:  169-172;  180-3,  November,  December,  1902. 

Kauffman:  BuU.  Torr.  Bot.  Club,  32:  333,  318,  June,  1905. 

Peck:  Rep.  N.  Y.  State  Mus.,  23:  105,  107,  108,  no,  112,  1873;  48:  245,  1895. 
Craterellus.     Peck:  Rep.  N.  Y.  State  Mus.,  37:  45,  1884,     Bull.  N.  Y.  State  Mus., 

i:  45,  May,  1887. 
Crepidotus.     Peck:  Rep.  N.  Y.  State  Mus.,  39. 
Entoloma.     Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  6:  99,  1883. 

Peck:  Rep.  N.  Y.  State  Mus.,  62. 
Fomes.     Murrill:  Bull.  Torr.  Bot.  Club,  30:  225-6,  April,  1903. 
Galera.     Peck:  Rep.  N.  Y.  State  Mus.,  23:  92,  1873;  46:  62,  1893. 
Ganoderma.     Murrill:  Bull.  Torr.  Bot.  Club,  29:  599-608,  i9o'2. 
Geaster.    Lloyd:  1902:  1^44. 

Hebeloma.     Peck:  Rep.  N.  Y.  State  Mus.,  23:  95,  1873;  63. 
Hydnum.     McIlvaine:  One  Thousand  American  Fungi,  494,  1900. 
Hygrophorus.     Peck:  Rep.  N.  Y.  State  Mus.,  23:  112,  1873;  60. 


APPENDLX  X  731 

Hypholoma.     McIlvaine:  One  Thousand  American  Fungi,  353,  355,  iQoo- 

Peck:  Rep.  N.  Y.  State  Mus.,  23:  98,  1873;  64. 
Inocybe.     Earle:  Torreya,  3:  168-170,  183-4,  November,  December,  1903. 
Lactarius.     Earle:  Torreya,  2:  139-41,  152-4,  October,  1902. 

Peck:  Rep.  N.  Y.  State  Mus.,  23:  114,  1873;  38-113,  1S85. 
Lepiota.     Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  6:  60,  1883. 

Peck:  Rep.  N.  Y.  State  Mus.,  20:  70,  1873,  35. 
Lentinus.     Earle:  Torreya,  3:  35-8,  March,  1903. 

Peck:  Rep.  N.  Y.  State  Mus.,  23:  126,  1873;  62. 
Lycoperdacese.     McIlvaine:  One  Thousand  American  Fungi,  577,  iQoo- 
Morgan:  Cin.  Soc.  Nat.  Hist.,  12:9,  April,  1889. 
Underwood:  Moulds,  Mildews  and  Mushrooms,  138,  1899. 
Lloyd:  Of  Australia,   New   Zealand  and   Neighboring   Islands,    1905:    1-42; 
Of  the  U.  S.     Mycol.  Notes,  20,  June,  1905. 
Lycoperdon.     McIlvaine:  One  Thousand  American  Fungi,  590,  1900- 
Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  13:  6,  April,  1891. 
Lloyd:  In  Europe,  Mycol.  Notes,  19,  May,  1905. 
Marasmius.     Peck:  Rep.  N.  Y.  State  Mus.,  23:  124,  1873  (Fig.  264). 
Mitremyces.     Lloyd:  Mycol.  Notes,  (218),  13:  125,  February,  1903. 
Mycena.     Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  6:  73,  1883. 

Peck:  Rep.  N.  Y.  State  Mus.,  23:  80,  1873. 
Naucoria.     Peck:  Rep.  N.  Y.  State  Mus.,  23:  91,  1873. 
Nidulariaceffi.     Underwood:  Moulds,  Mildews  and  Mushrooms,  142,  1899- 
White:  Bull.  Torr.  Bot.  Club,  29:  254,  May,  191 2. 
Lloyd:  1906:  1-32. 
Omphalia.     Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  6:  75,  1883. 
Peck:  Rep.  N.  Y.  State  Mus.,  23:  84,  1873;  45:  33,  1893. 
Panaeolus.     Peck:  Rep.  N.  Y.  State  Mus.,  23:  100,  1873. 
Panus.     Earle:  Torreya,  3:  86-7,  June,  1903. 
Pa.xillus.     Peck:  Rep.  N.  Y.  State  Mus.,  37:  30,  1884.     Bull.  N.  Y.  State  Mus. 

i:  30,  May,  1887. 
Phallus.     McIlvaine:  One  Thousand  American  Fungi,  571,  1900. 
Pholiota.     Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  6:  loi,  1883. 

Peck:  Rep.  N.  Y.  State  Mus.,  61. 
Pleurotus.     Morgan:  Jour.  Cin.  Soc.  Nat.  Hist.,  6:  77,  1883. 
Peck:  Rep.  N.  Y.  State  Mus.,  39:  59,  1886;  48:  275,  1895- 
Pluteolus.     Earle:  Torreya,  3:  124-5,  August,  1903. 

■  Peck:  Rep.  N.  Y.  State  Mus.,  46:  59,  1893. 
Pluteus.     McIlv.aine:  One  Thousand  American  Fungi,  243,  1900. 
Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  6:  97,  1883. 
Peck:  Rep.  N.  Y.  State  Mus.,  23:  61,  86,  1873;  38:  134,  1885. 
Polyporace®.     See  Murrill's  bibliography. 

Polystictus.    Lloyd:  Mycol.  Notes,  Polyporoid  Issue,  i,  February,  1908. 
Psalliota  (Agaricus).     Peck:  Rep.  N.  Y.  State  Mus.,  23:  97,  1893;  36:  42,  1883. 
Lloyd:  Mycol.  Notes,  4,  November,  1899. 


732  ADDITIONAL   EXERCISES 

Psathyra.     Peck:  Rep.  N.  Y.  State  Mus.,  64. 
Psathyrella.     Peck:  Rep.  N.  Y.  State  Mus.,  23:  102,  1873. 
Psilocybe.     Peck:  Rep.  N.  Y.  State  Mus.,  23:  99,  1873;  64. 
Russula.     Earle:  Torreya,  2:  101-3,  11 7-19,  July,  August,  1902. 

Peck:  Rep.  N.  Y.  State  Mus.,  23:  120,  1873;  60. 
Stropharia.  Earle:  Torreya,  3:  24,  February,  1903. 
Tricholoma.     Morgan:  Journ.  Cin.  Soc.  Nat.  Hist.,  6:  65,  1883. 

Peck:  Rep.  N.  Y.  State  Mus.,  23:  73,  1873;  44:  39,  40,  44,  52,  56,  61,  1891; 
48:  266,  1895. 
Volvaria.    Lloyd:  Volvaeof  U.  S.,  10,  1898.     McIlvaine:  One  Thousand  American 
Fungi,  239,  1900. 

APPENDIX  XI 

Key  to  Agaricace^ 

The  following  key  to  the  Agaricace^  is  taken  from  Bulletin  No.  175,  U.  S 
Department  of  Agriculture,  1915,  entitled  "Mushrooms  and  other  Common  Fungi" 
by  Flora  W.  Patterson  and  Vera  K.  Charles,  as  well  as  the  descriptions  of  a  few 
of  the  more  common  forms  selected  by  way  of  illustration. 

The  classification  of  the  genera  of  Agaricaceae  is  based  upon  the  color  of  the 
spores.  It  is  generally  a  comparatively  easy  matter  to  form  an  opinion  regarding 
the  color  of  the  spores,  but  if  any  difficulty  is  experienced  a  spore  print  may  be 
made.  The  process  is  very  simple,  and  the  results  are  quite  satisfactory.  The 
stem  is  removed  from  the  specimen  from  which  a  print  is  desired  and  the  cap 
placed  face  down  on  pieces  of  black  and  white  paper  placed  side  by  side  and 
covered  with  a  tumbler.  When  the  spores  are  mature  they  will  fall  in  radiating 
lines  on  the  pieces  of  paper.  If  a  permanent  spore  print  is  desired,  an  alcoholic 
spray  of  white  shellac  may  be  employed.  This  is  prepared  by  making  a  saturated 
solution  of  white  shellac  and  then  diluting  it  50  per  cent,  with  alcohol. 

Whites  pored  Agarics 

Plants  soft  or  more  or  less  fleshy,  soon  decaying,  not  reviving 
well  when  moistened: 
Ring  or  volva  or  both  present — 

Volva  and  ring  both  present Amanita. 

Volva  present,  ring  absent Amanitopsis. 

Volva  absent,  ring  present — 

Gills  free  from  stem Lepiota. 

Gills  attached  to  the  stem Armillaria. 

Ring  and  volva  both  absent — 

Stem  excentric  or  lateral !* Pleurotus. 

Stem  central- 
Gills  decurrent — 

Edge  blunt,  fold-like,  forked Cantharellus. 

Edge  thin,  stem  fibrous  outside Clitocybe. 


APPENDIX  XI  733 

Edge  thin,  stem  cartilaginous  outside Omphalia. 

Gills  sinuate,  general  structure  fleshy Tricholoma. 

Gills  adnate  or  adnexed — 

Cap  rather  fleshy,  margin  incurved  when  young Collybia. 

Plants  soft  or  more  or  less  fleshy,  etc. — Continued. 
Ring  and  volva  both  absent — Continued. 
Stem  central — Continued. 

Gills  adnate  or  adnexed — Continued. 
Cap  thin,  margin  of  the  cap  at  first  straight,  mostly 

bell-shaped Mycena. 

Cap  fleshy,  gills  very  rigid  and  brittle,  stem  stout — 

Milk  present Lactarius. 

Milk  absent Russula. 

Gills  various,  often  decurrent,  adnate  or  only  adnexed, 
edge  thin,  thick  at  junction  of  cap,  usually  distant, 

waxy Hygrophorus. 

Plants   coriaceous,   tough,   fleshy    or    membranaceous,    reviving 
when  moistened: 
Stem  generally  central,  substance  of  the  cap  noncontinuous 
with  that  of  the  stem,  gills  thin,  often  connected  by  veins 

or  ridges  (Fig.  264) Marasmius. 

Stem  central,  excentric,  lateral,  or  absent,  substance  of  the  cap 
continuous  with  that  of  the  stem — 

Edge  of  gills  toothed  or  serrate Lentinus. 

Edge  of  gills  not  toothed  or  serrate Panus. 

Edge  of  gills  split  into  two  laminae  and  revolute .  Schizophyllum. 

Plants  corky  or  woody,  gills  inatradig Lenzites. 


Rosy-s pored  Agarics 

Stem  excentric  or  absent  and  pileus  lateral Claudopus. 

Stem  central: 

Volva  present,  annulus  wanting Volvaria. 

Volva  and  annulus  absent — 

Cap  easily  separating  from  the  stem,  gills  free Pluteus. 

Cap  conflaent  with  the  stem,  gills  sinuate Entoloma. 


Ochres  pored  Agarics  {Spores  Yellow  or  Brown) 

Gills  easily  separable  from  the  flesh  of  the  cap: 

Margin  of  the  cap  incurved,  gills  more  or  less  decurrent  forked 

or  connected  with  veinlike  reticulations Paxillus. 

Gills  not  easily  separable  from  the  flesh  of  the  cap: 

Universal  veil  present,  arachnoid Cortinarius. 


734  ADDITIONAL  EXERCISES 

Universal  veil  absent — 

Ring  present Pholiota. 

Ring  absent — 
Stem  central — 

Cap  turned  in Naucoria. 

Cap  not  turned  in Galera. 

Stem  excentric  or  none Crepidotus. 


Browns  pored  A  garics 

Cap  easily  separating  from  the  stem,  gills  usually  free Agaricus. 

Cap  not  easily  separating  from  the  stem,  gills  attached: 

Ring  present. Stropharia. 

Ring  absent,  veil  remaining  attached  to  the  margin  of  the  cap. .  Hypholoma. 


Blacks  pored  Agarics 

Gills  deliquescing,  cap  thin,  ring  present  in  some  species Coprinus. 

Gills  not  deliquescing: 

Margin  of  cap  striate,  gills  not  variegated Psathyrella. 

Margin  of  cap  not  striate,  gills  variegated Pan^olus. 

The  genus  Amanitais,  easily  recognized  among  the  white-spored  agarics  in  typical 
species,  or  early  stages,  by  the  presence  of  a  volva  and  a  veil.  Young  plants  are  com- 
pletely enveloped  by  the  volva,  and  the  manner  in  which  it  ruptures  varies  according 
to  the  species.  The  volva  may  persist  in  the  form  of  a  basal  cup,  as  rings,  or  scales, 
on  a  bulb-like  base,  or  it  may  be  friable  and  evanescent.  The  cap  is  fleshy,  convex, 
then  expanded.  The  gills  are  free  from  the  stem,  which  is  different  in  substance 
from  the  cap  and  readily  separable  from  it. 

This  is  a  most  interesting  genus,  on  account  of  the  great  beauty  of  color  and  tex- 
ture of  many  of  its  species  and  the  fact  that  it  contains  the  most  poisonous  of  all 
mushrooms.  While  there  are  some  edible  species  in  the  genus,  the  safest  policy 
for  the  amateur  is  to  avoid  all  mushrooms  of  the  genus  Amanita. 


Amanita  caesarea.     CcEsar's  Mushroom 

Cap  ovate  to  hemispherical,  smooth,  with  prominently  striate  margin,  reddish  or 
orange  becoming  yellow;  gills  free,  yellow;  stem  cylindric,  only  slightly  enlarged 
at  the  base,  attenuated  upward,  flocculose,  scaly  below  the  annulus,  smooth  above; 
ring  membranaceous,  large,  attached  from  its  upper  margin;  stem  and  ring  nor- 
mally orange  or  yellowish,  in  small  or  depauperate  specimens  sometimes  white; 
flesh  white,  yellow  under  the  skin,  and  usually  yellow  next  to  the  gills;  volva  large, 
distinct,  white,  sac-like. 

Cap  2  3^^  to  4  or  more  inches  broad ;  stem  3  to  s  inches  long. 

This  species  is  variously  known  as  Csesar's  agaric,  royal  agaric,  orange  Amanita, 


APPENDIX  XI 


735 


etc.  It  has  been  highly  esteemed  as  an  article  of  diet  since  the  time  of  the  early 
Greeks.  It  is  particularly  abundant  during  rainy  weather  and  may  occur  solitary, 
several  together,  or  in  definite  rings.  Although  this  species  is  edible,  great  caution 
should  always  be  used  in  order  not  to  confound  it  with  Amanilar  Frostlana,  which  is 
poisonous.  The  points  of  difference  of  these  two  species  are  conveniently  compared 
as  follows: 


Fig.  264. — Fruit  bodies  of  fairy-ring  toadstool  (Marasmiits  oyeades).  {After 
Patterson,  Flora  W.,  and  Charles,  Vera  K.,  Bull.  175,  U.  S.  Dept.  Agric,  pi.  xix, 
Apr.  29,  1915-) 


Species 

Cap 

Gills 

Stem 

Volva 

Amanita  caesarea. 

i 
Orange,  smooth,  1  Yellow 

Yellow.... 

White,  sometimes 

.  occasionally  with 

breaking   up   in- 

a few  fragments 

to     soft,     fluffy 

of    V  0  1  V  a    as 

masses. 

patches. 

Amanita  Frostiana 

Yellow,    smooth 

Yellow    or 

White    or 

Yellow,     some- 

or with  yellowish 

tinged    with 

yellow. 

times      breaking 

scales.                      yellow. 

up     into     fluffy, 
yellow     frag- 

ments. 

Amanita  muscaria.     The  Fly  Amauila  {Very  Poisonous) 

Cap  globose,  convex,  and  at  length  flattened,  at  maturity  margin  sometimes 
slightly  striate;  flesh  white,  sometimes  yellow  under  the  pellicle;  remnants  of  the 


736  ADDITIONAL   EXERCISES 

volva  persisting  as  scattered,  floccose,  or  rather  compact  scales,  color  subject  to 
great  variation,  ranging  from  yellow  to  orange,  or  blood  red,  gills  white  or  yellow- 
ish, free  but  reaching  the  stem;  stem  cylindrical,  at  first  stuffed,  later  hoUow,  upper 
part  torn  into  loose  scales,  bulb  prominent,  generally  marked  by  concentric  scales 
forming  irregular  ridges;  ring  typically  apical,  lacerated,  lax,  large. 

Cap  33-2  to  $}^  inches  broad,  stem  4  to  6  inches  long. 

Amanita  muscaria  may  be  found  during  the  summer  and  fall,  occurring  singly,  or 
in  small  associations,  or  in  patches  of  considerable  size.  It  grows  in  cultivated  soil, 
partially  cleared  land,  and  in  woods  or  roadsides.  It  does  not  demand  a  rich  soil, 
but  rather  exhibits  a  preference  for  poor  ground.  The  color  is  an  exceedingly  vari- 
able character,  the  plants  being  brighter  colored  when  young,  and  fading  as  they 
mature.  The  European  plant  possesses  more  gorgeous  colors  than  the  American 
form. 

This  is  a  very  poisonous  species,  and  it  has  been  the  subject  of  many  pharmaco- 
logical and  chemical  investigations.  Its  chief  poisonous  principle  is  muscarine, 
although  a  second  poisonous  element  is  believed  to  be  present,  as  atropine  d(Jes  not 
entirely  neutralize  the  effect  of  injections  of  Amanita  muscaria  in  animals. 

This  species  has  been  responsible  for  many  deaths,  and  numerous  cases  of  severe 
illness  have  been  caused  by  persons  mistaking  Amanita  muscaria,  the  poisonous 
species,  for  Amanita  caesarea,  the  edible  species.  The  most  satisfactory  treatment 
is  to  administer  hypodermic  injections  of  atropine  beginning  with  a  dosage  of  }io 
grain  after  the  giving  of  a  strong  emetic.  While  typical  specimens  of  these  two 
species  possess  distinguishing  characters,  as  already  shown,  it  is  again  recommended 
to  shun  all  Amanitae. 

In  Siberian  Russia  the  natives  make  several  uses  of  Amanita  muscaria.  Pre- 
served in  salt  it  is  eaten,  though  probably  more  as  a  condiment  than  as  a  main 
article  of  diet;  a  decoction  is  popular  as  an  intoxicant,  and  deaths  are  reported  upon 
good  authority  as  resulting  from  a  "muscaria  orgy." 


Amanita  phalloides.     Death  Cup  {Deadly  Poisonous) 

Cap  white,  lemon,  or  olive  to  umber,  fleshy,  viscid  when  moist,  smooth  or  with 
patches  or  scales,  broadly  oval,  bell-shaped,  convex,  and  finally  expanded,  old  speci- 
mens sometimes  depressed  by  the  elevation  of  the  margin;  gills  free,  white;  stem 
generally  smooth  and  white,  in  dark  varieties  colored  like  the  cap  but  lighter,  solid 
downward,  bulbous,  hollow,  and  attenuated  upward;  ring  superior,  reflexed,  gener- 
all}^  entire,  white. 

The  large,  free  volva,  its  lower  portion  closely  adherent  to  the  bulb,  and  the  large 
ring  are  of  assistance  in  distinguishing  this  species. 

Cap  3  to  4  inches  broad;  stem  3  to  5  inches  long. 

This  species  and  its  forms  are  subject  to  great  variation  in  color,  ranging  from 
white,  pale  yellow,  and  olive  to  brown.  Amanita  phalloides  is  a  very  cosmopolitan 
plant  and  one  of  very  common  occurrence.  It  is  the  most  dangerous  of  all  mush- 
rooms, for  no  antidote  to  overcome  its  deadly  effect  is  known.  It  exhibits  no  special 
preference  as  regards  habitat  and  is  found  growing  in  woods  or  cultivated  land  from 


APPENDIX  XI  -  737 

summer  to  late  autumn.     When  fresh  it  is  without  scent,  but  a  peculiarly  sickening 
odor  is  present  in  drying  plants. 

Armillaria 

The  genus  Armillaria  is  another  white-spored  agaric  having  a  ring  and  no  volva. 
The  gills  are  attached  to  the  stem  and  are  sinuate  or  more  or  less  decurrent.  The 
substance  of  the  stem  and  cap  is  continuous  and  firm.  This  genus  may  be  distin- 
guished from  Amanita  and  Lepiota  by  the  continuity  of  the  substance  of  the  stem 
and  cap,  and  it  is  further  differentiated  from  Amanita  by  the  absence  of  a  volva. 
It  contains  several  edible  species. 


Armillaria  mellea.     Honey-colored  Mushroom  {Edible) 

Cap  oval  to  convex  and  expanded,  sometimes  with  a  slight  elevation,  smooth,  or 
adorned  with  pointed  dark-brown  or  blackish  scales,  especially  in  the  center,  honey 
color  to  dull  reddish-brown,  margin  even  or  somewhat  striate  when  old;  gills  adnate 
or  decurrent,  white  or  whitish,  sometimes  with  reddish-brown  spots;  stem  elastic, 
spongy,  sometimes  hollow,  smooth  or  scaly,  generally  whitish,  sometimes  gray  or 
yellow  above  the  ring,  below  reddish-brown. 

Cap  i^^  to  6  inches  broad;  stem  2  to  6  inches  long,  ^-'2  to  %  inch  thick. 

This  species  is  extremely  common  and  variable.  It  generally  occurs  in  clusters 
about  the  base  of  rotten  stumps  and  is  often  a  serious  parasite  of  fruit  trees  and 
destructive  to  props  in  coal  mines.  The  fruit  bodies  are  attached  to  the  strands  of 
hyphae  known  as  Rhizomorpha  subterranea,  which  form  a  network  under  the  bark 
of  the  tree  and  out  into  the  soil.  Both  ring  and  stem  are  subject  to  marked  varia- 
tions. The  former  may  be  thick,  or  thin,  or  entirely  absent,  and  the  latter  uniform 
in  diameter  or  bulbous.  The  species  is  edible,  though  not  especially  tender  or 
highly  flavored  (Fig.  15). 

On  account  of  the  great  variation  in  color,  surface  of  the  cap,  and  shape  of  the 
stem,  several  forms  of  Armillaria  mellea  have  been  given  varietal  distinction.  The 
following  varieties  as  distinguished  by  Prof.  Peck  may  be  of  assistance  to  the  amateur: 

Armillaria  mellea  var.  flava,  with  yellow  or  reddish-yellow  cap. 
Armillaria  mellea  var.  radicata,  with  a  tapering  root. 
Armillaria  mellea  var.  albida,  with  white  or  whitish  cap. 


Pleurotus 

The  genus  Pleurotus  is  chiefly  distinguished  among  the  white-spored  agarics  by 
the  excentric  stem  or  resupinate  cap.  The  stem  is  fleshy  and  continuous  with  the 
substance  of  the  cap,  but  it  is  subject  to  great  variation  in  the  different  species  and 
may  be  excentric,  lateral,  or  entirely  absent.  The  gills  are  decurrent  or  sometimes 
adnate,  edge  acute.  Most  of  the  species  grow  on  wood,  buried  roots,  or  decayed 
stumps.  This  genus  corresponds  to  Claudopus  of  the  pink-spored  and  Crepidotus 
of  the  brown-spored  forms. 
47 


738 


ADDITIONAL   EXERCISES 


Pleurotiis  oslreatus.     Oyster  Mushroom  (Edible) 

Cap  either  sessile  or  stipitate,  shell-shaped  or  dimidiate,  ascending,  fleshy,  soft, 
smooth,  moist,  in  color  white,  cream,  grayish  to  brownish  ash;  stem  present  or  absent 
(if  present,  short,  firm,  elastic,  ascending,  base  hairy);  gills  white,  decurrent,  some- 
what distant,  anastomosing  behind  to  form  an  irregular  network. 

Cap  3  to  5  inches  broad;  mostly  cespitose  imbricated  (Fig.  265). 

A  very  fine  edible  species,  growing  on  limbs  or  trunks  of  living  or  dead  trees,  of 
cosmopolitan  distribution,  appearing  from  early  summer  until  late  fall. 


Fig.  265. — Sporophores  of  oyster  toadstool  {Pleurotus  oslreatus).  {After  Patter- 
son, Flora  W.,  and  Charles,  Vera  K.,  Bull.  175,  U.  S.  Dept.  Agric.  pi.  vii,  Apr.  29, 
191S.) 

Pleurotus  sapidus  (Edible) 

This  species  very  closely  resembles  Pleurotus  ostrealus  and  is  distinguished  from 
it  by  the  lilac-tinged  spores,  a  character  difficult  or  impossible  for  the  amateur  to 
detect.  From  the  mycophagist's  point  of  view,  these  two  species  are  equally 
attractive. 


Pleurotus  serotinus  (Edible) 

Cap  fleshy,  compact,  convex  or  nearly  plane,  dimidiate  reniform,  suborbicular, 
edge  involute,  finally  wavy,  smooth,  yellowish-green,  sooty  olive,  or  reddish-brown, 
in  wet  weather  with  a  viscid  pellicle;  gills  close,  distinct,  whitish  or  yellowish, 
minutely  tomentose  or  squamulose  with  blackish  points. 

Cap  I  to  3  inches  broad. 


APPENDIX  XI  739 

In  general  appearance  this  fungus  resembles  Claudopiis  nidulans,  but  is  sepa- 
rated from  it  by  the  color  of  the  spores,  Pleurohis  belonging  to  the  section  of  white- 
spored  agarics  and  Claudopus  to  the  rosy-spored  species.  The  plants  grow  on  dead 
branches  or  trunks  and  are  gregarious  or  imbricate. 

Pleurotus  serotinus  is  edible  but  not  particularly  good,  its  chief  recommendation 
being  the  lateness  of  its  occurrence  in  the  fall,  when  other  more  tempting  species 
have  disappeared. 

Pleurotus  ulmarius  {Edible) 

Cap  fairly  regular,  although  inclined  to  excentricity,  convex,  margin  incurved, 
later  plane,  horizontal,  even,  smooth,  white  or  whitish,  at  disk  shades  of  tan  or 
brown;  flesh  white,  tough;  gills  broad,  rather  distant  or  rounded  behind;  stem  more 
or  less  excentric,  curved,  ascending,  firm,  solid,  elastic,  thickened,  and  tomentose  at 
the  base. 

Cap  3  to  5  inches  broad,  stem  2  to  3  inches  long. 

This  species  occurs  abundantly  on  dead  elm  branches  or  trunks  or  growing  from 
wounds  of  living  trees.  Though  exhibiting  a  special  fondness  for  this  host,  it  is  not 
confined  to  elm  trees.  It  is  readily  distinguished  from  Pleurotus  ostreatus  by  the 
long  stem  and  by  the  emarginate  or  rounded  gills.  It  is  considered  an  excellent 
edible  species  and  occurs  abundantly  in  the  fall. 

Cantharellus 

In  the  genus  Cantharellus  the  cap  is  fleshy  or  submembranaceous,  continuous 
with  the  stem,  and  has  the  margin  entire,  wavy,  or  lobed.  The  gills  are  decurrent, 
thick,  narrow,  blunt,  fold-like,  irregularly  forked,  and  connected  by  net-like  veins. 

Cantharellus  aurantiactis.    False  Chanterelle 

Cap  fleshy,  soft,  somewhat  silky,  shape  variable,  convex,  plane  or  infundibuli- 
form,  margin  wavy  or  lobed,  inroUed  when  young,  later  simply  incurved,  dull  orange 
or  brownish,  especially  in  the  center;  flesh  yellowish;  gills  rather  thin,  decurrent, 
forked,  dark  orange;  stem  spongy,  fibrous,  colored  like  the  cap,  larger  at  the  base 
than  at  the  apex. 

Plant  I  to  3  inches  in  height;  cap  i  to  3  inches  broad. 

This  plant  is  more  slender  and  the  gills  are  thinner  than  those  of  Cantharellus 
cibarius,  from  which  it  can  be  readily  distinguished.  The  taste  is  generally  mild, 
but  sometimes  slightly  bitter.  Foreign  and  American  mycophagists  do  not  agree  in 
regard  to  the  edibility  of  the  species.  It  is  common  on  the  ground  or  on  very  rotten 
logs. 

Cantharellus  cibarius.     The  Chanterelle  (Edible) 

Cap  fleshy,  thick,  smooth,  irregularly  expanded,  sometimes  deeply  depressed, 
opaque  egg  yellow,  margin  sometimes  wavy;  flesh  white;  gills  decurrent,  thick 
narrow,  branching  or  irregularly  connected,  same  color  as  cap;  stem  short,  solid 
expanding  into  a  cap  of  the  same  color. 


740  ADDITIONAL  EXERCISES 

Plant  2  to  4  inches  in  height;  cap  2  to  3  inches  broad. 

An  agreeable  odor  of  apricots  may  be  observed,  especially  in  the  dried  plants  of 
this  species,  but  its  absence  need  not  be  construed  as  affecting  the  validity  of  an 
identification  established  by  other  characters.  The  chanterelle  has  long  been  con- 
sidered one  of  the  most  highly  prized  edible  mushrooms.  The  remark  of  a  foreign 
mycologist  is  recalled  that  "The  chanterelle  is  included  when  the  most  costly 
dainties  are  sought  for  state  dinners."  It  is  a  common  summer  species  found  in 
open  woods  and  grassy  places. 

Lactarius 

The  distinguishing  feature  of  the  genus  Lactarius  is  the  presence  of  a  white  or 
colored  milk,  especially  in  the  gills.  The  entire  plant  is  brittle  and  inclined  to 
rigidity.  The  fleshy  cap  is  more  or  less  depressed  and  frequently  marked  with 
concentric  zones.  The  gills  are  often  somewhat  decurrent,  but  in  certain  species 
are  adnate  or  adnexed,  unequal  in  length,  and  often  forked.  The  stem  is  stout, 
rigid,  central,  or  slightly  excentric. 

Lactarius  chelidonium  (Edible) 

Cap  firm,  convex  and  depressed  in  the  center,  glabrous,  slightly  viscid  when  moist, 
grayish-yellow  or  tawny,  at  length  stained  bluish  or  greenish,  generally  zonate,  mar- 
gin involute  at  first  and  naked;  gills  narrow,  crowded,  sometimes  forked,  and  some- 
times joining  to  form  reticulations,  adnate  or  slightly  decurrent,  saffron  yellow  to 
salmon;  stem  short,  nearly  equal,  hollow,  colored  like  the  cap. 

Cap  2  to  2^^  inches  broad;  stem  i  to  i}^  inches  long,  about  3'2  inch  thick. 

This  species  is  closely  related  to  Lactarius  deliciosus,  to  which  in  flavor  and  sub- 
stance it  is  scarcely  inferior.  It  is  paler  than  that  species  and  the  milk  is  saffron 
yellow  rather  than  orange.  The  plants  are  fragile  and  when  wounded  turn  blue, 
and  later  green.  They  are  to  be  found  especially  in  dry  localities  in  the  vicinity  of 
pine  woods  in  September  and  October. 

Lactarius  deceptivus  (Edible) 

Cap  fleshy,  convex  umbilicate,  then  expanded  and  centrally  depressed,  somewhat 
infundibuliform,  white  or  whitish,  margin  at  first  involute,  covered  with  a  dense  soft 
cottony  tomentum,  filling  the  space  between  the  margin  and  the  stem,  finally  spread- 
ing or  elevated  and  more  or  less  fibrillose;  gills  whitish  or  cream-colored,  rather 
broad,  distant  or  subdistant,  adnate  or  decurrent,  forking;  stem  solid,  nearly  equal, 
pruinose-pubescent. 

Cap  2^^^  to  53'^  inches  broad;  stem  %  inch  to  3  inches  long. 

Lactarius  deceptivus  is  found  in  woods  and  open  places  from  July  to  September. 
It  is  coarse,  but  fairly  good  after  its  peppery  taste  is  lost  by  cooking. 

Lactarius  deliciosus  (Edible) 

Cap  convex,  but  depressed  in  the  center  when  quite  young,  finally  funnel-shaped, 
smooth,  slightly  viscid,  deep  orange,  yellowish  or  grayish-orange,  generally  zoned. 


APPENDIX  XI  741 

margin  naked,  at  first  involute,  unfolding  as  the  plant  becomes  infundibuliform; 
flesh  soft,  pallid;  gills  crowded,  narrow,  often  branched,  yellowish-orange;  stem 
equal  or  attenuated  at  the  base,  stuffed,  then  hollow,  of  the  same  color  as  the  cap 
except  that  it  is  paler  and  sometimes  has  dark  spots. 

Cap  2  to  5  inches  broad;  stem  i  to  2  inches  long,  i  inch  thick. 

This  fungus  is  distinctive,  on  account  of  its  orange  color  and  the  concentric  zones 
of  light  and  dark  orange  on  the  cap  and  because  of  the  saffron  red  or  orange  milk. 
A  peculiarity  of  the  plant  is  that  it  turns  green  upon  bruising  and  in  age  changes  from 
the  original  color  to  greenish.  Lactarius  deliciosus  is  widely  distributed  and  of  com- 
mon occurrence,  appearing  on  the  ground  in  woods,  solitary  or  in  patches,  from  June 
or  July  to  October.  As  the  name  indicates,  it  is  considered  a  delicious  species,  and 
that  it  has  a  preeminent  claim  to  the  name  is  unchallenged.  Even  by  the  ancients 
it  was  considered  "food  for  the  gods." 

Lactarius  fumosus  (Suspicious) 

Cap  convex,  plane  or  slightly  depressed,  snuff  brown  or  coffee-colored,  dry  gla- 
brous or  pruinose,  very  smooth,  margin  entire  or  sometimes  wavy;  flesh  white, 
changing  to  reddish  when  wounded;  gills  subdistant,  adnate,  or  slightly  decurrent, 
white  then  yellow,  becoming  pinkish  or  salmon  where  bruised;  stem  nearly  equal  or 
slightly  tapering  downward,  stuffed,  then  hollow,  colored  like  the  cap. 

Cap  2  to  3  inches  broad;  stem  i^  to  2,1/^  inches  long,  about  6  lines  thick. 

This  species  varies  considerably  in  size,  color,  and  closeness  of  the  gills.  The 
distinguishing  features  for  field  identification  are  the  coffee-colored  cap  and  the 
changeable  color  of  the  flesh  and  gills.  Its  use  should  be  strictly  avoided,  as  it 
closely  resembles  Lactarius  fidiginosus,  a  poisonous  species.  These  two  species, 
L.  fumosus  and  L.  fuUginosus,  are  sometimes  considered  identical. 1 

Lactarius  indigo  (Edible) 

Cap  at  first  umbilicate  and  the  margin  involute,  later  cap  depressed  or  infundibuli- 
form and  margin  elevated,  indigo  blue  with  a  silvery-gray  luster,  zonate,  fading  in 
age,  becoming  greenish  and  less  distinctly  zoned,  milk  abundant  and  dark  blue; 
gills  crowded,  indigo  blue,  changing  to  greenish  in  age;  stem  short,  nearly  equal, 
hollow. 

Cap  2  to  5  inches  broad;  stem  i  to  2  inches  long. 

Lactarius  indigo  is  easily  recognized  by  its  striking  blue  color.  It  occurs  in  mixed 
Qr  coniferous  woods  in  summer  and  autumn.  Though  not  particularly  abundant, 
several  plants  are  generally  found  in  fairly  close  range  of  one  another. 

Lactarius  piperatus.     Pepper  Cap  (Edible) 

Cap  fleshy,  thick,  convex,  umbilicate,  when  mature  funnel-shaped,  even,  smooth, 
zoneless,  margin  involute  when  young;  flesh  white;  gills  narrow,  crowded,  edge 

1  BURLINGHAM,  GERTRUDE  S. :  Study  of  the  Lactari«  of  the  United  States. 
Memoirs,  Torr.  Bot.  Club,  Vol.  14,  No.  i,  p.  84,  1908. 


742  ADDITIONAL  EXERCISES 

obtuse,  in  some  forms  arcuate,  and  then  extended  upward,  white,  reported  wish 
occasional  yellow  spots;  stem  equal  or  tapering  below,  thick,  white,  sometimet 
pruinose. 

Cap  3)-^  to  5  inches  broad,  sometimes  reported  considerably  larger;  stem  i  to 
inches  long. 

The  mUk  in  the  "pepper  cap"  is  abundant,  white,  unchangeable,  and  extremely 
acrid,  to  which  character  is  due  the  specific  name.  This  species  is  very  common  and 
abundant  from  June  to  October. 

Lactarius  torminosus  (Poisonous) 

Cap  convex  then  depressed,  surface  viscid  when  young  or  moist,  yellowish-red  or 
ochraceous  with  pink  shades,  margin  involute  when  young,  persistently  tomentoes 
hairy;  gills  crowded,  narrow,  often  tinged  with  yellow  or  flesh  color;  stem  cylin- 
drical or  slightly  tapering  at  the  base,  hollow,  whitish. 

Cap  2  to  3H  inches  broad;  stem  iM  to  3  inches  long,  4  to  8  ilnes  thick. 

According  to  some  authors  this  species  is  injurious  only  when  raw.  It  is  cooked 
and  eaten  in  Sweden.  In  Russia  it  is  enjoyed  dressed  with  oil  and  vinegar  or  it 
is  preserved  by  drying. 

Lactarius  volemus  (Edible) 

Cap  convex,  nearly  plane  or  slightly  depressed,  glabrous,  dry,  azonate,  brownish 
terra  cotta,  somewhat  wrinkled  when  old;  gills  adnate  or  slightly  decurrent,  close, 
whitish,  becoming  sordid  or  brownish  when  bruised;  stem  more  or  less  equal,  firm, 
solid,  glabrous,  colored  like  the  cap  or  paler;  milk  white,  abundant,  and  mild,  be- 
coming thick  when  exposed  to  the  air. 

Cap  2  to  5  inches  broad;  stem  i  to  4  inches  long,  4  to  10  lines  thick. 

This  species  is  considered  delicious,  and  is  quite  common  from  midsummer  to 
frost  on  semicleared  or  sprout  land. 

•    RUSSULA 

The  genus  Russula  is  similar  in  form,  brittleness,  and  general  appearance  to 
Lactarius,  from  which  it  differs  only  in  the  absence  of  milk.  The  species  are  very 
abundant  in  the  summer,  extending  into  the  fall  months. 

Most  species  of  Russula  are  regarded  as  edible,  but  several  are  known  to  be 
poisonous.  It  is  advisable  to  abstain  from  eating  any  red  forms  until  perfectly 
familiar  with  the  different  species. 

Russula  emelica  (Poisonous) 

Cap  oval  to  bell-shaped,  becoming  flattened  or  depressed,  smooth,  shining,  rosy 
to  dark  red  when  old,  fading  to  tawny,  sometimes  becoming  yellow,  margin  finally- 
furrowed  and  tuberculate;  flesh  white,  but  reddish  under  the  separable  pellicle; 
gills  nearly  free,  somewhat  distant,  shining  white;  taste  very  acrid;  stem  stout, 
spongy-stuffed,  fragile  when  old,  white  or  reddish. 


APPENDIX  XI  743 

Cap  3  to  4  inches  broad;  stem  2^2  to  4  inches  long. 

Russula  emetica  is  a  handsome  plant  of  wide  distribution  found  during  summer 
and  autumn  on  the  ground  in  woods  or  open  places.  Although  some  enthusiastic 
mycophagists  testify  to  its  edibility,  it  is  best  to  consider  the  species  poisonous. 

Russula  ochrophylla 

Cap  convex,  becoming  nearly  plane  or  very  slightly  depressed  in  the  center,  when 
old  purple  or  purplish  red,  margin  even,  sometimes  faintly  striate  when  old;  flesh 
white,  purplish  under  the  cuticle;  gills  adnate,  entire,  a  few  forked  at  the  base,  inter- 
spaces somewhat  venose,  at  first  yellowish,  ochraceous  buff  when  mature,  powdery 
from  the  spores;  stem  mostly  equal,  solid  or  spongy  within,  rosy  or  red,  paler  than 
the  cap. 

Cap  2  to  4  inches  broad;  stem  2^^  to  3  Inches  long. 

Russula  ochrophylla  may  be  found  growing  singly,  or  in  small  patches  on  the 
ground  in  woods,  mostly  under  trees,  according  to  Prof.  Peck,  especially  under  oak 
trees.  In  Virginia,  Maryland,  and  the  District  of  Columbia  it  is  abundant  in  July 
and  August  and  is  to  be  found  less  frequently  in  September  and  the  first  part  of 
October. 

Russula  roscipcs  {Edible) 

Cap  conve.x,  sometimes  plane  or  slightly  depressed,  at  first  viscid,  then  dry  and 
faintly  striate  on  the  margin,  rosy  red,  frequently  modified  by  pink  or  ochraceous 
shades;  gills  moderately  close,  ventricose,  more  or  less  adnate,  whitish  becoming 
yellow;  stem  stout,  stuffed  or  somewhat  hollow,  white  tinged  with  red. 

Cap  I  to  2  inches  broad;  stem  i3'^  to  3  inches  long. 

This  species  grows  on  the  ground  in  mixed,  but  generally  coniferous,  woods.  It 
appears  in  the  late  summer  and  autumn  and  is  reported  excellent,  though,  as  already 
stated,  the  amateur  should  be  cautious  and  avoid  all  red  species  of  this  genus. 

Russula  rubra 

Cap  convex,  flattened,  finally  depressed,  dry,  pellicle  absent,  polished,  cinnabar 
red,  becoming  tan  when  old;  flesh  white,  reddish  under  the  cuticle;  gills  adnate, 
somewhat  crowded,  whitish  then  yellowish,  often  red  on  the  edge;  stem  stout,  solid, 
varying  white  or  red. 

Cap  2%  to  4  inches  broad;  stem  2  to  3  inches  long,  about  i  inch  thick. 

This  species  is  extremely  acrid,  and,  as  there  are  conflicting  opinions  concerning 
its  edibility,  it  is  best  for  the  amateur  to  refrain  from  collecting  it.  It  is  found  in 
woods  on  the  ground  in  summer  and  autumn. 

Russula  viresccns  {Edible)    . 

Cap  at  first  rounded,  then  expanded,  when  old  somewhat  depressed  in  the  center, 
dry,  green,  the  surface  broken  up  into  quite  regular,  more  or  less  angular  areas  of 
deeper  color,  margin  straight,  obtuse,  even;  gills  adnate,  somewhat  crowded,  equal 
or  forked;  stem  equal,  thick,  solid  or  spongy  rivulose,  white. 


744  ADDITIONAL  EXERCISES 

Cap  3^-^  to  5  inches  broad;  stem  about  2  inches  long. 

This  fungus  is  noticeable  on  account  of  the  color  and  areolate  character  of  the 
cap.  In  Virginia,  Maryland,  and  the  District  of  Columbia  it  occurs  commonly  either 
solitary  or  in  small  patches,  but  not  in  very  great  abundance,  from  July  to  September, 
but  it  has  been  found  from  June  through  the  entire  summer  and  into  October.  The 
species  is  edible  and  of  good  flavor. 

CORTINARIUS 

The  genus  Corlinarius  is  easily  recognized  when  young  among  the  ocher-spored 
agarics  by  the  powdery  gills  and  by  the  cobwebby  veil,  which  is  separable  from  the 
cuticle  of  the  cap.  In  mature  plants  the  remains  of  the  veil  may  often  be  observed 
adhering  to  the  margin  of  the  cap  and  forming  a  silky  zone  on  the  stem.  Corlinarius 
contains  many  forms  which  are  difficult  of  specific  determination.  Many  species 
are  edible,  some  indifferent  or  unpleasant,  and  others  positively  injurious.  The 
colors  are  generally  conspicuous  and  often  very  beautiful.  Most  of  the  species 
occur  in  the  autumn. 

Corlinarius  cinnamomeus  (Edible) 

Cap  rather  thin,  conic  campanulate,  when  expanded  almost  plane,  but  sometimes 
umbonate,  yellow  to  bright  cinnamon-colored,  with  perhaps  red  stains,  smooth,  silky 
from  innate,  yellowish  fibrils,  sometimes  concentric  rows  of  scales  near  the  margin; 
flesh  yellowish;  gills  yellow,  tawny,  or  red,  adnate,  slightly  sinuate  and  decur- 
rent  by  a  tooth,  crowded,  thin,  broad;  stem  equal,  stuffed  then  hollow,  yellowish, 
fibrillose. 

Cap  I  to  2}^  inches  broad;  stem  2  to  4  inches  long,  3  to  4  lines  thick. 

This  is  a  very  common  and  widely  distributed  species,  particularly  abundant  in 
mossy  coniferous  woods  from  summer  until  fall.  The  color  of  the  gills  is  an  extremely 
variable  character,  ranging  from  brown  or  cinnamon  to  blood  red.  A  form  possess- 
ing gills  of  the  latter  color  is  known  as  Corlinarius  cinnamomeus  var.  semisanguineus. 
This  species  and  variety  are  edible  and  considered  extremely  good. 

Corlinarius  liloiinus  {Edible) 

Cap  firm,  hemispherical,  then  convex,  minutely  silky,  lilac-colored;  gills  close, 
violaceous  changing  to  cinnamon;  stem  solid,  stout,  distinctly  bulbous,  silky  fibril- 
lose,  whitish  with  a  lilac  tinge. 

Cap  2  to  3  inches  broad;  stem  2  to  4  inches  long. 

This  is  a  comparatively  rare  but  very  beautiful  mushroom  and  an  excellent  edible 
species. 

Corlinarius  sanguineus  {Edible) 

Cap  convex,  then  plane,  or  perhaps  slightly  umbonate  or  depressed,  blood  red, 
silky  or  squamulose;  flesh  paler  reddish;  gills  crowded,  entire,  adnate,  dark  blood 
red;  stem  stuffed  or  hollow,  sometimes  attenuated  at  the  base,  dark  as  the  cap  and 
fibrillose,  containing  a  red  juice. 


APPENDIX  XI  745 

Cap  I  to  1%  inches  broad;  stem  2  to  3  inches  long. 

This  species  is  much  less  common  in  its  occurrence  than  Corlinarius  cinnamomeus, 
but  is  distinctive  because  of  its  entire  blood-red  color. 

Corlinarius  violaceus  {Edible) 

Cap  convex,  when  expanded  almost  plane,  dry  with  hairy  tufts  or  scales,  dark 
violet;  flesh  somewhat  violaceous;  gills  distant,  rather  thick  and  broad,  rounded  or 
deeply  notched  at  apex  of  stem,  narrowed  at  margin  of  cap,  at  first  violaceous,  later 
brownish-cinnamon;  stem  fibrillose,  solid,  bulbous,  colored  like  cap. 

Cap  2  to  4  inches  broad;  stem  3  to  5  inches  long. 

This  very  attractive  species  is  at  first  a  uniform  violet,  but  with  age  the  gills 
assume  a  cinnamon  hue.  The  plants  appear  in  woods  and  open  places  during  the 
summer  and  fall,  generally  solitary,  but  often  in  considerable  numbers.  It  is 
esteemed  as  one  of  the  best  edible  species. 

Agaricus 

The  genus  Agaricus  is  characterized  by  brown  or  blackish  spores  with  a  purplish 
tinge  and  by  the  presence  of  a  ring.  The  cap  is  mostly  fleshy  and  the  gills  are  free 
from  the  stem.  The  genus  is  closely  related  by  Stropharia,  but  separated  from  it 
by  the  free  gills  and  the  noncontinuity  of  the  stem  and  the  cap.  The  species  of 
Agaricus  occur  in  pastures,  meadows,  woods,  and  manured  ground.  All  are  edible, 
but  certain  forms  are  of  especially  good  flavor.  Bright  colors  are  mostly  absent 
and  white  or  dingy  brown  shades  predominate. 

Agaricus  arvensis.     Horse  or  Field  Mushroom  (Edible) 

Cap  convex,  bell-shaped,  then  expanded,  when  young  floccose  or  mealy,  later 
smooth,  white  or  yellowish;  flesh  white;  gills  white  to  pink,  at  length  blackish-brown, 
free,  close,  may  be  broader  toward  the  stem;  stem  stout,  hollow  or  stuffed,  may  be 
slightly  bulbous,  smooth;  ring  rather  large,  thick,  the  upper  part  white,  membrana- 
ceous, the  lower  yellowish  and  radially  split. 

Cap  3  to  5  inches  broad;  stem  2  to  5  inches  high,  4  to  10  lines  thick. 

Agaricus  arvensis  is  to  be  found  in  fields,  pastures,  and  waste  places.  It  is  closely 
related  to  the  ordinary  cultivated  mushroom,  but  differs  in  its  larger  size  and  double 
ring.  It  is  an  excellent  edible  species,  the  delicacy  of  flavor  and  texture  largely 
depending,  like  other  mushrooms,  upon  its  age. 

Agaricus  campestris.     Common  or  Cultivated  Mushroom  (Edible) 

Cap  rounded,  convex,  when  expanded  nearly  plane,  smooth,  silky  floccose  or 
squamulose,  white  or  light  brown,  squamules  brown,  margin  incurved;  flesh  white, 
firm;  gills  white  in  the  button  stage,  then  pink,  soon  becoming  purplish-brown,  dark 
brown,  or  nearly  black,  free  from  the  stem,  rounded  behind,  subdeliquescent;  stem 
white,  subequal,  smooth  or  nearly  so;  veil  sometimes  remaining  as  fragments  on  the 
margin  of  cap;  ring  frail,  sometimes  soon  disappearing. 


746 


ADDITIONAL  EXERCISES 


Cap  1 3^  to  4  inches  broad;  stem  2  to  3  inches  long,  4  to  8  lines  thick.  (Fig.  266.) 
This  is  the  most  common  and  best  known  of  all  the  edible  mushrooms.  It  is  a 
species  of  high  commercial  value,  lending  itself  to  very  successful  and  profitable 
artificial  cultivation.  It  is  cosmopolitan  in  its  geographic  distribution,  being  as 
universally  known  abroad  as  in  America.  It  is  cultivated  in  caves,  cellars,  and  in 
especially  constructed  houses;  but  it  also  occurs  abundantly  in  the  wild  state,  appear- 
ing in  pastures,  grassy  places,  and  richly  manured  ground.  The  only  danger  in 
collecting  it  in  the  wild  form  is  in  mistaking  an  Amanita  for  an  Agaricus;  however, 
this  danger  may  be  obviated  by  waiting  until  the  gills  are  decidedly  pink  before  col- 
lecting the  mushrooms. 


Fig.  266. —  Meadow  mushroom,  Agaricus  campestris  var.  Columbia,  showing  all 
stages  in  development  of  young  mushrooms  (fruit  bodies).  {From  Gager,  after  G.  F. 
Atkinson.) 


Agaricus  placomyces.    Flat-cap  Mushroom  {Edible) 

Cap  thin,  at  first  broadly  ovate,  convex  or  expanded  and  flat  in  age,  whitish, 
adorned  with  numerous  minute,  brown  scales,  which  become  crowded  in  the  center, 
forming  a  large  brown  patch;  gills  close,  white,  then  pinkish,  finally  blackish-brown; 
veil  broad;  ring  large.  In  the  early  stages,  according  to  Prof.  Atkinson,  a  portion  of 
the  veil  frequently  encircles  the  stipe  like  a  tube,  while  a  part  remains  still  stretched 
over  the  gills. 


APPENDIX   XI  747 

Stem  smooth,  stuffed  or  hollow,  bulbous,  white  or  whitish,  the  bulb  often 
stained  with  yellow. 

Cap  2  to  4  inches  broad;  stem  3  to  5  inches  long,  3^  to  K  inch  thick. 
This  species  frequents  hemlock  woods,  occurring  from  July  to  September. 

Agaricus  Rodmani  {Edible) 

Cap  firm,  rounded,  convex,  then  nearly  plane,  white,  becoming  subochraceous, 
smooth  or  cracked  into  scales  on  the  disk,  margin  decurved;  flesh  white;  gills  nar- 
row, close,  white,  changing  to  pink  and  blackish-brown;  stem  solid,  short,  whitish, 
smooth,  or  perhaps  mealy,  squamulose  above  the  ring;  ring  double,  sometimes  ap- 
pearing as  two  collars  with  space  between. 

Cap  2  to  4  inches  broad;  stem  2  to  3  inches  long,  6  to  10  lines  thick. 

Agaricus  Rodmani  may  easily  be  mistaken  for  Agaricus  campestris,  but  can  be  dis- 
tinguished by  the  thicker,  firmer  flesh,  narrower  gills,  which  are  nearly  white  when 
young,  and  peculiar  collar,  which  appears  double.  This  species  grows  on  grassy 
ground,  often  springing  from  crevices  of  unused  pavements  or  between  the  curbing 
and  the  walk.     It  is  to  be  found  principally  from  May  to  July. 

Agaricus  silvicola  (Edible) 

Cap  convex,  expanded  to  almost  plane,  sometimes  umbonate,  smooth,  shining, 
white,  often  tinged  with  yellow,  sometimes  with  pink,  especially  in  the  center;  flesh 
white  or  pinkish;  gills  thin,  crowded,  white,  then  pink,  later  dark  brown,  distant 
from  stem,  generally  narrowed  toward  each  end;  stem  long,  bulbous,  stuffed  or  hol- 
low, whitish,  sometimes  yellowish  below;  ring  membranaceous,  sometimes  with 
broad  floccose  patches  on  the  under  side. 

Cap  3  to  6  inches  broad;  stem  4  to  6  inches  long,  4  to  8  lines  thick. 

Agaricus  silvicola  has  been  known  under  various  names,  at  one  time  being  consid- 
ered merely  a  variety  of  Agaricus  arvensis.  By  Peck^  it  has  been  recognized  as  a 
distinct  species,  A .  abrupiibulbus.  A  discussion  of  the  nomenclature  of  this  species 
may  be  found  in  Mcllvaine  and  Macadam.* 

Agaricus  subrufescens  (Edible) 

Cap  at  first  deeply  hemispherical,  becoming  convex  or  broadly  expanded,  silky, 
fibrillose,  and  minutely  or  obscurely  squamulose,  whitish,  grayish,  or  dull  red- 
dish-brown, usually  smooth  and  darker  on  the  disk;  flesh  white,  unchangeable; 
gills  at  first  "white  or  whitish,  then  pinkish,  finally  blackish-brown;  stem  rather  long, 
often  somewhat  thickened  or  bulbous  at  the  base,  at  first  stuffed,  then  hollow,  white; 
the  annulus  flocculose  or  floccose  squamose  on  the  lower  surface.     Two  additional 

1  Peck,  C.  H.:  Report  of  the  State  Botanist,  1904.  N.  Y.  State  Mus.  Bull.  94, 
p.  36,  1905. 

2  McIlvaine,  Charles,  and  Macadam,  R.  K.:  Toadstools,  Mushrooms,  Fungi, 
Edible  and  Poisonous;  One  Thousand  American  Fungi,  rev.  ed.,  Indianapolis 
(1912),  p.  728. 


748 


ADDITIONAL   EXERCISES 


characters  of  assistance  in  identification  are  the  mycelium,  which  forms  slender 
branching  root-like  strings,  and  the  almond-like  flav'or  of  the  flesh. 

Cap  3  to  4  inches  broad;  stem  aj-^  to  4  inches  long. 

The  plants  often  grow  in  large  clusters  of  twenty  to  thirty  or  even  forty  indi- 
viduals. They  occur  in  the  wild  state  and  have  also  been  reported  as  a  volunteer 
crop  in  especially  prepared  soil.     Specimens  collected  in  the  vicinity  of  Washington, 


Fig.   267. — Fruit  bodies  of  Coprinus  alramenlariiis  (edible).      {After  Patterson,  Flora 
W.,  and  Charles,  VercfK.,  Bull.  175,  U.  S.  Dept.  Agric,  pi.  xxviii,  Apr.  25,  ipiS-) 


D.  C,  were  found  growing  near  the  river  on  a  rocky  slope  rich  in  leaf  mould. 
cus  subrufescens  is  considered  a  very  excellent  edible  species. 


Agari- 


COPRINUS 


The  genus  Coprinus  is  easily  recognized  by  the  black  spores  and  the  close  gills, 
which  at  maturity  dissolve  into  an  inky  fluid.  The  stem  is  hollow,  smooth,  or 
fibrillose.  The  volva  and  ring  are  not  generic  characters,  but  are  sometimes  pres- 
ent. The  plants  are  more  or  less  fragile  and  occur  on  richly  manured  ground,  dung, 
or  rotten  tree  trunks.  The  genus  contains  species  of  excellent  flavor  and  delicate 
consistency.     Autodigestion  (page  65)  is  shown  by  them. 


APPENDIX  XI  749 

Coprinus  atramenlarius.     Inky  Cap  {Edible)  (Fig.  267). 

Cap  ovate,  slightly  expanding,  silvery  to  dark  gray  or  brownish,  smooth,  silky  or 
with  small  scales,  especially  at  the  center,  often  plicate  and  lobed  with  notched  mar- 
gin; gills  broad,  ventricose,  crowded,  free,  white,  soon  changing  to  pinkish-gray, 
then  becoming  black  and  deliquescent;  stem    smooth,    shining,    whitish,    hollow, 


Fig.   268. — Edible  shaggymane,   Coprinus  comatus.      {After  Patterson,  Flora  W.,  and 
Charles,  Vera  K.,  Bull.  175,  U.  S.  Dept.  Agric,  pi.  xxii,  Apr.  29,  1915.) 

attenuated  upward,  readily  separating  from  the  cap;  ring  near  the  base  of  stem, 
evanescent. 

Cap  13-2  to  4  inches  broad;  stem  2  to  4  inches  long,  4  to  6  lines  thick. 

This  species  appears  from  spring  to  autumn,  particularly  after  rains.  It  grows 
singly  or  in  dense  clusters  on  rich  ground,  lawns,  gardens,  or  waste  places.  It  has 
long  been  esteemed  as  an  edible  species.  Coprinus  atramenlarius  differs  from  C. 
comalus  in  the  more  or  less  smooth,  oval  cap  and  the  imperfect,  basal,  evanescent 
ring. 


750  ADDITIONAL   EXERCISES 

Coprinus  contains.     Shaggy  Mane  (Edible)  (Figs.  268  and  270). 

Cap  oblong,  bell-shaped,  not  fully  expanding,  fleshy  at  center,  moist,  cuticle 
separating  into  scales  that  are  sometimes  white,  sometimes  yellowish  or  darker,  and 
show  the  white  flesh  beneath,  splitting  from  the  margin  along  the  lines  of  the  gills; 
gills  broad,  crowded,  free,  white,  soon  becoming  pink  or  salmon-colored  and  chang- 
ing to  purplish-black  just  previous  to  deliquescence;  stem  brittle,  smooth  or  fibril- 


FiG.   269. — Glistening  inky  cap,  Coprinus  micaceus.      (Pholo  by  W.  H.   Walmsley.) 

lose,  hollow,  thick,  attenuated  upward,  sometimes  slightly  bulbous  at  base,  easily 
separating  from  the  cap;  ring  thin,  movable. 

Cap  usually  ij'^  to  3  inches  long;  stem  2  to  4  inches  long,  4  to  6  lines  thick. 

This  species  has  a  wide  geographic  distribution  and  is  universally  enjoyed  by 
mycophagists.  The  fungus  is  very  attractive  when  young,  often  white,  again  show- 
ing gray,  tawny,  or  pinkish  tints.  It  appears  in  the  spring  and  fall,  sometimes  soli- 
tary, sometimes  in  groups,  on  lawns,  in  rich  soil,  or  in  gardens. 


APPENDIX  XI 


751 


Coprinus  fimetarius 

Cap  at  first  cylindrical,  later  conical  to  expanded,  margin  splitting,  revolute  or 
upturned,  grayish  to  bluish-black,  surface  at  first  covered  with  white  scales,  finally 
smooth;  gills  black,  narrow;  stem  fragile,  white,  squamulose,  hollow,  but  solid  and 
bulbous  at  the  base. 

Cap  I  inch  or  more  across,  stem  3  or  more  inches  high. 

This  is  a  very  common  and  abundant  species  on  manure  or  rich  soil  and  occurs 
from  spring  to  winter.     It  is  edible  and  considered  excellent. 


it  Hi 


Fig.  270. — Shaggymane  toadstool  {Coprinus  comatus)  growing  in  open  fields 
and  on  lawns.  Edible  before  it  begins  to  deliquesce.  {After  Gager,  C.  S.:  Funda- 
mentals of  Botany,  1916:  289.) 


Coprinus  micaceus.     Mica  Inky  Cap  (Fig.  269). 

Cap  ovate,  bell-shaped,  light  tan  to  brown,  darker  when  moist  or  old,  often 
glistening  from  minute,  mica-like  scales,  margin  closely  striate,  splitting,  and  revo- 
lute; gills  narrow,  crowded,  white,  then  pink  before  becoming  black;  stem  slender, 
white,  hollow,  fragile,  often  twisted. 

Cap  I  to  2  inches  broad;  stem  2  to  4  inches  long  and  2  to  3  lines  thick. 

This  glistening  little  species  occurs  very  commonly  at  the  base  of  trees  or  spring- 
ing from  dead  roots  along  pavements,  or  more  uncommonly  on  prostrate  logs  in 
shady  woods.  The  plants  appear  in  great  profusion  in  the  spring  and  early  summer, 
and  more  sparingly  during  the  fall.  Coprinus  micaceus  is  a  very  delicious  mush- 
room and  lends  itself  to  various  methods  of  preparation. 


INDEX 

A  list  of  the  common  and  important  diseases  of  economic  plants  in  the  United 
States  and  Canada  will  be  found  on  pages  414  to  474.  The  scientific  names  of 
the  various  disease-producing  organisms  and  their  common  names  will  be  found 
there,  arranged  alphabetically  according  to  the  host  plants  on  which  they  grow. 
These  names  have  been  omitted  from  this  index. 


Abnormalities,  classification  of,  331 

Abortion,  331 

Abrasion,  294 

Acaulosy,  331 

Account     of     specific     plant     diseases, 

475  et.  seq. 
Acetic  acid  fermentation,  32 
Acheilary,  332 

A-chlya,  figures  of  species,  112 
Achlya  polyandra  on  water  plants,  1 1 1 
Achlya  prolifera,  zoospores  of,  67 
Acid  injuries,  649 

Acid  spotting  of  morning  glories,  293 
Acrasiales,  8 
Acrasis  granulata,  8 
Actinomyces  bovis,  39 
Actinomyces  chromogenes,  39,  266,  544 
Actinomyces  myricarum,  39 
Actinomycetaceae,  39 
Activators,  57 
Adenopetaly,  332 
Adesmy,  332 
Adherence,  332 
Adhesion,  332 
^cidium,  188 
^ciospores,  188 
JEduia,  188 

Aerobic  cultivation,  625 
Aerobic  organisms,  27 
/^thalium,  13 

Agalinis  as  root  parasite,  299 
Agaricaceae,  characters  of  family,   231, 

232 
Agaricaceae,  Key  to,  732,  733,  734 


Agaricus  arvensis,  description  of,  745 
Agaricus    campestris,    analysis    of,  55; 
fat  content,   56;  fed  to  Plasmodium, 
12;   figure  of,  234,     746;  description 
ofj  745)  746;  number  of  spores,  234, 
Agaricus,  description  of  genus,  745 
Agaricus  placomyces,  description  of,  746 
Agaricus  Rodmani,  description  of,  747 
Agaricus  silvicola,  description  of,  747 
Agaricus  spectabilis,  resin  in,  56 
Agaricus   subrufescens,    description    of, 

747 
Agar-agar,  605 
Agars,  various,  606,  611 
Air  content  of  tissues  and  disease,  280 
Albinism,  343 
Albumen  of  egg,  603 
Alcoholic  fermentation  59;  in  yeasts,  138 
Alfalfa,  leaf  spot  of,  476,  477;  leaf  rust, 

477 
Algae  in  lichens  78;  parastic,  391 
Alteration  of  position,  347 
Alternation    of    generations    in    rusts, 

diagram  of,  194 
Alternaria  citri,  533;  dianthi  on  carna- 
tions,   488,    489,  "490;    violae,    558; 
figure  of,  559 
Alternariose  of  carnation,  488,  489,  490; 

figure  of,  489 
Amanita  caesarea,  description  of,  734, 
735,  muscaria,  description  of,  735, 
736;  at  edge  of  woods,  83;  figure  of, 
233;  phalloidea,  description  of,  736; 
figure  of,  238;  in  woods,  83. 


753 


754 


Amanitopsis   vaginata,   speed   of   spore 

fall,  64 
Aniaurochaete,  spores  of,  16 
American     Phytopathological     Society, 

status  of,  411 
Amidase,  58 
Amcebobacter,  39 
Amphibolips  ilicifolia,  gall  producing  on 

Quercus  nana,  399 
Amphispores,  188 
Amphitrichous,  23 
Amygdalin,  59 
Amylase,  58 
Anaeretic,  332 

Anaerobic  cultivation,  625;  organisms,  27 
Analysis  of  water,  626 
Anatomy,  pathologic  plant,  354 
Anbury,  487 

Ancyclistaceae,  characters  of,  118 
Animals  as  cause  of  disease,  275 
Animal  galls,  296;  injuries,  295,  309 
Animate  agents  of  disease,  295 
Annulus  superus,  233 
Anther  smuts,  72 
Antherophylly,  332 
Anthesmolysis,  332 
Anthocyanin,  360 
Antholysis,  329,  332 
Anthracnose  of  cotton  508;  of  melons, 

52s;  of  raspberry,  544 
Anthrax,  35 
Anthurus  borealis,  252 
Anti-enzymes,  58 
Antisepsis,  692 
Aphylly,  332 
Apilary,  332 
Aplanobacter,  35 
Apogamy,  332 
Apophysis,  332 
Apostasis,  333 

Apothecium,  structure  of,  121 
Apple,  black-rot  of,  478,  479;  bitter-rot 

of,   477,   478;  fruit  spots  570;  scab, 

478,  480,  481;  figures  of,  480;  tumor 

on  stem,  figure  of,  390 
Appel,  O.,  work  of,  272,  273 


Appel's  potato  scab,  646 

Appressoria,  308 

Arcyria,  15 

Armillaria  mellea,  62,  83,  530;  color  of, 

S3;  described,  46,  737;  figure  of,  47 
Arrestment  of  cell  wall  development,  359 
Arthrospores  in  bacteria,  25 
Artificial  wounds,  295 
Asci  of  chestnut  blight,  figure  of,  500 
Ascobolacese,  characters  of,  166 
Ascobolus  immersus,  special  methods  of 

spore  discharge,  66 
Ascobolus,  spore  colors  of,  54 
Ascochyta  pisi,  534 
Ascogenous  hyphal  system,   figures  of, 

125,  127 
Ascoideaceae,  120 
Ascomycetales,    bibliography    of,    174, 

17s.  176;  general  characters  of,  121, 

122;  phylogeny  of,  173,  174;  sexuality 

of,  122 
Ascospores  50;  germination  in  chestnut 

blight,  figure  of,  5^1;  representation 

by  figures  of  development,  128 
Ascus  50;  diagrams  of,  by  Claussen,  124 
Ash,  heart  rot  of,  481,  483 
Ashlock,  J.  L.,  quoted,  182 
Ash  of  fungi,  analysis  of,  54 
Asiatic  cholera,  37 
Asparagus  rust,  191,  483,  484 
Aspergillacese,  characters  of,  143 
Aspergillus,  characters  of  the  genus,  144 
Aspergillus    fumigatus    as    pathogenic, 

147;    flavus,     147;    giganteus,     147; 

Key  to  species  of,   702-703;  nidulans, 

figure  of,  148;  niger  with  lipase,  59; 

with   raffinase-58;    luchuensis,    147; 

oryzete,    146;    figure    of,    145;    with 

diastase  58;  tokelau,  147;  Wentii,  146 
Asphyxiation  of  roots,  565 
Assimilation  tissues  of  galls,  400 
Astrffius,  244 
Atkinson,    Geo.    F.,   book   quoted,   91; 

quoted,  235,  236;  work  of,  248,  249 
Atrichous,  23 
Atrophy,  333,  342 


755 


Auerbach's  stain,  591 
Auriculariaceae,  characters  of  family,  216 
Auricularia  Auricula- Judae,  216 
Autodigestion  of  Coprinus  comatus,  65; 

of  fungi,  54 
Autophyllogeny,  33;^ 
Awamori,  a  beverage,  147 


B 


Bacillus  amylobocter,  36;  spores  in,  25; 
amylovorus  36,  536,  644;  aroideae, 
36;  Biitschli,  spores  in,  25;  butyricus, 
36;  calf  actor,  36;  carotovorus,  36; 
caucasicus  in  Kefir,  141;  coli,  36; 
inflatus,  spores  in,  25;  influenzae, 
length  and  breadth  of,  22;  lathyri, 
547;  loxosporus,  spores  in,  25; 
loxosus,  spores  in,  25;  megatherium, 
nuclear  material  in,  24;  mesentericus 
vulgatus  as  a  milk  curdler,  59; 
musae,  36,  484;  nitri,  length  and 
breadth  of,  22;  nuclear  material  in, 
24;  phytophthorus  313,  646;  prodi- 
giosus,  36;  and  high  temperatures,  360; 
putrificus,  36;  radicicola,  29,  36,  612; 
involution  forms,  30;  sub  tills,  36; 
rapidity  of  cell  division,  24;  spores  in, 
25;  tetani,  36;  tracheiphilus,  36,  313, 
525 

Bacteria,  fermentation,  32;  as  disease 
producers,  275;  bibliography,  40; 
characterization,  638;  classification  of, 
28;  in  general,  21;  kinds  of  spores  in, 
25;  of  root  tubercles,  figures  of,  31; 
systematic  account,  34 

Bacteriaceae,  35 

Bacteriology  emphasized,  271;  systema- 
tic, 630,  631 

Bacteriopurpurin,  38 

Bacterium,  35;  aceticum,  36;  fermenta- 
tion by,  32;  acidi-lactici,  36;  fermen- 
tation by,  32;  in  Matzoon,  141; 
anthracis,  35;  campestris,  485,  486, 
487;  diptheridis,  35;  gammari,  nuclear 
material  in,  24;  influenzae,  35;  Kiitz- 
47 


ingianus,  fermentation  by,  320;  leprae 
35;  Pasteurianus,  fermentation  by, 
32;  mallei,  35;  michiganense,  35; 
pestis,  35;  phosphoreum,  36;  pneu- 
moniae, 35;  Rathayi,  35;  tuberculosis, 
35;  vermiforme  in  ginger  beer,  140 

Balance,  organic,  ^5^ 

Balanophoraceae,  parasites  of,  299 

Banana  bud-rot,  484 

Bark-boring  beetles,  294 

Basidiobolus  ranarum  on  frog  drug,  85 

Basidiolichenes,  81 

Basidiomycetales,  characters  of,  177; 
Key  to  suborders,  177 

Basidiospores,  49,  187 

Basidium,  187 

Bastard  toad-flax,  298 

Beam  of  light  method  of  studying  spore 
discharge,  64 

Bean  mosaic,  577 

Beefsteak  fungus,  230 

Beet  leaf-spot,  484,  485 

Beet  rust,  485 

Beetles,  bark  boring,  294 

Beggiatoa,  38;  alba,  38;  length  and 
breadth  of,  22;  mirabilis,  38;  length 
and  breadth  of,  22 

Beggiatoaceae,  38 

Benecke,  W.,  mentioned,  54 

Benzaldehyde,  59 

Biastrepsis,  333 

Bibliography  of  Ascomycetales,  174, 
i75>  176;  of  bacteria,  40;  of  disease 
prevention,  318;  of  galls,  401,  402; 
of  non-parasitic  diseases,  580;  of 
Oomycetales,  118,  119;  of  plant 
diseases  in  general,  353;  of  rusts,  214, 
215,  216;  of  slime  moulds,  18,  19,  20; 
of  smuts,  185,  186;  of  works  on  plant 
diseases,  412;  of  Zygomycetales,  105 

Biciliate  zoospores,  escape  of,  67 

Binucleate  hyphal  cells  of  Gasteromy- 
cetes,  218;  of  Hymenomycetes,  218 

Biochemic  features  of  bacteria,  636 

Biting  insects,  296 

Bitter-pit  of  apples,  570 


756 


INDEX 


Bitter-rot  of  apple,  477,  478 

Birds  as  spore  carriers,  67 

Black  ball,  178 

Black  Death,  35 

Blackman,  O.  H.,  work  on  rusts,  191 

Black-knot  of  plum  74,  540 

Black-rot  of  apple,  478,  479;  of  cabbage 

485,  486,  487;  of  cruciferous  plants, 

experiments  with,  645;  of  grape,  512; 

figures  of,  S13,  514;  of  orange,   533, 

of  sweet  potato,  548 
Black-rust  of  wheat,  560 
Blakeslee,  A.  F.,  work  on  moulds,  93 
Blanched  plants,  277 
Blastomany,  ^^^ 

Blight  of  chestnut  491;  of  sycamore,  549 
Blister-rust  of  white  pine,  537;  figure  of, 

538 
Blood  serum,  604 
Boletoideae,  234 
Boletus,  change  of  color  in,  53;  felleus, 

230;  figure  of,  228;  manual  of,  227 
Books   on  chlorosis,   328;  on   economic 

entomology,  296 
Bordeaux  mixture,  figure  of  apparatus 

for  making,  672;  formulae  for,  670-674 
Botrytis  cinerea,  chitin  in  sclerotia  of,  52 
Bouillon,  601 
Bourquelat  mentioned,  53 
Breeding  for  disease  resistance,  325 
Brefeld,  Dr.  O.,  cited,  89 
Bronzing,  282 
Broom-rape  as  a  parasite,  299;  figure  of, 

300 
Brown-rot  of  cacao,  490;  of  lemon,  520; 

of  turnip,  figure  of,  486 
Brown  rust  of  rye,  202 
Buchner  discovery  of  zymase,  56 
Bud-rot  of  banana,  484 
Bulboceras    gallicus    and    underground 

truffles,  71 
Buller,  A.  H.  F.  book  of,  233 
Bunt  ear,  178 

Burgeff,  H.,  work  cited,  100 
Burl  on  oak  trees,  figure  of,  350 
Burrs,  348 


Burt,  E.  A.,  work  of,  248 
Butyric  fermentation,  33,  59 


Cabbage  black-rot,  485,  486,  487 
Cabbage   leaf,   figure  of  hypertrophied 

mesophyll,  368 
Cacao  brown-rot,  490 
Cacao  pink  disease,  490 
Casoma,    188;    nitens,  binucleate  secio- 

spores  of,  196 
Calciphile  plants,  277 
Calciphobe  plants,  277 
Calcium,  influence  of,  277 
Calcium  oxalate  in  sporangial  walls  of 

Mucor  mucedo,  53 
Calendar  for  spraying,  680-690 
Calico,  description  of,  327 
Callous  formation,   conditions  of,   380, 

381;   experiments   with,   648;   hyper- 
trophies, 368,  369 
Callus,  377  et  seq.;  definition  of,  377; 

histology  of,  379 
Calvatia  cyathiformis,  figure  of,  242 
Calvatia,  species  of,  242 
Calycanthemy,  333 
Calyphemy,  333 
Calyptospora  species  of,  199 
Cancer  in  plants,  34 
Cancer-root,  figure  of,  301 
Canker  lesion  of  chestnut,  figure  of,  492 
Canker  of  larch,  519 
Cankers,  342,  348 
Cantharellus     aurantiacus,    description 

of,   739;  cibarius,  description  of,  739, 

740 
Capillitium,  formation  of,   13;  in  slime 

moulds,  15 
Carbohydrates,  58 
Carbol  fuchsin,  589 
Carbon  circulation,  33 
Carnation  alternariose,   488,   489,   490; 

figure  of,  489 
Carrion    fungi,    development    of,     248 
Cassytha  filiformis,  306 


INDEX 


757 


Catalase,  58,  59 

Catalyst,  56 

Cataplasms,  376,  385;  histology  of,  391 

Cataplastic  hypertrophy,  364 

Catastome,  243,  244 

Cavities  covered  with  metal,  323 

Cavity  treatment,  321 

Cecidial  tissue  forms,  397  et.  seq. 

Cecidium,  384 

Cecidologists,  385 

Cedar    apple,  figure    of,    206,    394;    on 

small  twig,  figure  of  section  of,  395 
Cedar  rust  on  apple,  209 
Celidiaceae,  169 
Cell  division  in  bacteria,  24 
Celloidin  method,  655 
Celtis  occidentalis,  witches'  broom   on, 

351 
Cement  cavity  fillings,   figure  of,   322; 

mixing  and  placing,  321 
Cenangiaceae,  169 
Cenanthy,  S33 

Cerastium  viscosum,  anther  smut  of,  72 
Ceratiomyxa,  spores  of,  16 
Ceratomany,  333 
Cercospora  beticola,  267;   on  beet,  484, 

485;  coffeicola,  503 
Cetraria  islandica  on  ground,  83 
Chaetocladiace^e,  characters  of,  103 
Chaetocladium  Jonesii,  loi 
Chaetocladium  parasitic  on  Mucor,  83 
Chaetomiacese,  characters  of,  163 
Characterization  of  bacteria,  638 
Charles,  Vera  K.,  bulletin  of,  244 
Cheilomany,  333 
Chemic  character  of  soil  cause  of  disease, 

276 
Chemic  elements  in  fungi,  54 
Chemic  work  on  fungi,  55 
Chemistry   emphasized,  271;    of  fungi, 

52;  of  mushrooms,  237 
Cliemomorphosis,  404 
Chemotaxis,  60 
Chemotropism,  60 
Cherry  leaf-curl,  491 
Cherry,  powdery  mildew  of,  491 


Chestnut  blight,  491;  distribution  of, 
84;  spread  of,  316;  gelatinous  threads, 
figure  of,  494;  perithecial  pustules, 
493 

Chestnut  killed  by  blight,  figure  of,  313 

Chestnut  leaf  mildew,  502 

Chestnut,  V.  K.,  bulletin  of,  238 

Chimaeras,  329,  330;  periclinal,  330; 
sectorial,  330;  spontaneous,  330 

Chimney  sweeper,  178 

Chinese  yeast,  99 

Chitin  in  bacterial  cell  wall,  22 

Chlamydobacteriaceae,  37 

Chlamydomucor  racemosus,  figure  of, 
98,  99 

Chlamydospores,  50;  of  corn  smut,  ger- 
mination of,  507;  of  smuts,  179;  of 
Tilletia  foetans,  figure  of,  561 

Chlamydothrix,  37 

Chloranthy,  37,  329,  333 

Chlorophyljess  plants,  i 

Chlorosis,  327,  343,  650;  books  on,  328 

Choanephoraceas,  brief  characterization 
of,  103 

Chondromyces,  39 

Cholesterin,  56 

Cholin,  56 

Chorisis,  333 

Christman,  A.  H.,  work  on  rusts,  191 

Chromatin  in  bacteria,  23;  in  fungi,  53 

Chromatium,  39;  Okeni,  length  and 
breadth  of,  22 

Chromogenic  bacteria,  25,  26 

Chromoparous,  26 

Chromophorous,  26 

Chromosomes  in  fungi,  53;  reduction,  53 

Chymosin,  59 

Chytridiaceae,  characters  of,  116,  117, 
118 

Circasa  lutetiana,  giant  cells,  figure  of 
372 

Cladochytricce,  116,  117 

Cladomany,  333 

Cladonia  cristatella  on  dead  wood,  83; 
pyxidata  on  stumps,  83;  rangiferina 
on  ground,  83 


758 


INDEX 


Cladothrix,   38;   dichotoma,   38;   fungi- 

formis,  38;  intestinalis,  38;  intrica,  38; 

profundus,  38;  rufula,  38 
Classification,    i;    of    bacteria,    28;    of 

enzymes,  58;  of  fungi,  2-6 
Clathraceae,  characters  of  family,   251; 

distribution  of  genera  and  species  of, 

87,  88 
Clathrus    cancellatus,    figure    of,     247; 

columnatus,  development  of,  248 
Claussen,   P.,   reinvestigation  of   Pyro- 

nema  confluens,  123;  work  cited,  108 
Clavaria,  species  of,  223 
Clavariaceae,  characters  of  family,  222 
Claviceps     purpurea,     546;     chitin     in 

sclerotia   of,    52;   described,    162;  fat 

content,    56;    figures    of,    160,    161; 

sclerotia  of,  69 
Cleanliness  to  prevent  disease,  367 
Cleavage  blocks  in  formation  of  spores 

in  slime  moulds,  14 
Climatic  factors  of  disease,  281 
Clostridium  butyricum,  36 
Clotting  enzymes,  59 
Clouds,  influence  of,  284 
Clover  rust,  502 
Club-root,  487,  488;  figure  of  on  cabbage 

roots,  488;  of  cabbage,  figure  of,  10 
Coagulation,  59 

Cobb's  disease  of  sugar  cane,  37 
Coccaceae,  34 
Coconut  water,  599 
Cocoon  disease  of  silkworms,   147 
Coelonemata,  15 
Coenobia,  21 
Coffee  leaf-spot,  503 
Coffee  rust,  503 
Cohesion,  333 

Collection  of  fungi,  726,  727 
Coleosporiaceae,    characters    of    family, 

199 
Coleosporium   solidaginis   and   sickness 

of  horses,  200 
CoUetotrichum    gossypii,   508;    lagena- 

rium,    525;    Lindemuthianum,     264; 

figures  of,  265;  species  of,  266 


CoUybia  dryophila,  fall  of  spores  of,  64; 
platyphylla  on  decaying  logs,  74 

Colonies,  types  of,  626,  627 

Colors  of  bacteria,  26;  in  fungi,  53;  of 
Plasmodia,  12 

Columella  in  slime  moulds,  15 

Comandra  umbellata,  298 

Comatricha  nigra,  figure  of,  14;  ob- 
tusata,  13 

Conchs,  342 

Conidiophore,  46 

Conidiospore,  46,  49 

Coniferin,  56,  59 

Coniothyrium  Fuckelii,  262 

Conopholis  americana,  299;  figure  of, 
301;  mexicana,  299 

Connold,  Edward  T.,  work  of  on  galls, 
384 

Cook,  Mel.  T.,  work  of,  274 

Coprinus,  deliquescence  of,  53;  descrip- 
tion of  genus,  748;  atramentarius, 
749;  figure  of,  748;  corpatus,  850; 
figure  of,  749,  751;  fed  to  Plasmo- 
dium, 12;  liberation  of  spores,  65; 
number  of  spores  in,  234;  fimetarius, 
751;  micaceus,  751;  figure  of,  750; 
stercorarius,  61;  occurrence  of,  83 

Coprophilous  fungi  and  their  spores,  68 

Cora,  a  lichen,  81 

Cordyceps  Hiigelii,  figure  of,  70;  mili- 
taris,  figure  of,  70;  on  larvas  of  insects, 
69;  ophioglossoides,  figure  of,  70; 
parasitic  on  Elaphomyces,  69;  sev- 
eral sp'ecies  described,  162;  sphaero- 
cephala,  figure  of,  70 

Coremium,  50 

Coriolus  versicolor,  occurrence  of,  229 

Cork  as  a  protective  layer,  308 

Corn  dry-rot,  504 

Corn  smut  on  tassels,  figure  of,  506; 
smut,  504,  505,  506;  wilt,  507 

Correlation,  404 

Corticium  lilaco-fuscum,  490;  vagum- 
solani,  221,  269 

Cortinarius  cinnamomeus,  description 
of,    744;   description   of  genus,    744; 


INDEX 


759 


lilacinus,  description  of,  744;  san- 
guineus, 744;  violaceus,  color  of,  53; 
description  of,  745 

Coryphylly,  333 

Cotton,  508;  boll  anthracnose,  508; 
rust,  508;  wilt,  646 

Cottony  cushion  scale,  ravage  of,  316 

Counter,  plate,  628 

Counting  methods,  620,  621 

Counting  plate,  Jeffer's,  628 

Cover-glasses,  squared,  616 

Cow  wheat  as  a  root  parasite,  299 

Cowpea  wilt,  646 

Cracks,  frost,  294 

Cranberry,  509;  gall,  509;  scald,  509; 
detailed  figures  of,  510,  511 

Crateria,  334 

Craterium  leucocephalum,  figure  of,  17 

Crenothrix,  38;  polyspora,  38 

Cribraria  argillacea,  lead-colored  Plas- 
modium of,  12;  purpurea,  scarlet 
Plasmodium  of,  12;  violacea,  violet 
Plasmodium  of,  12 

Cronartium  ribicola,  313,  537;  figure  of, 
538 

Crown-gall  experiments  with,  643; 
figure  of  an  apple  with,  352;  nuclear 
division,  figure  of,  373;  on  geranium, 
figure  of,  644;  on  raspberry,  figure  of, 

391 
Crucibulum,  245,  246 
Crustaceous  lichens,  79 
Cryptogamic  parasites,  298 
Cultivation    of    bacteria    and    fungi, 

rough    method,    587;    of    mushroom, 

236,  237,  693 
Cultural  features  of  bacteria,  descriptive 

terms  of,  633 
Culture  media,  standardization  of,  613 
Cultures  of  de  Vries,  328 
Curdling,  59 

Curly-dwarf  of  potato,  576 
Curly- top  of  beets,  573 
Curricula  and  plant  pathology,  410 
Cuscuta,   description  of,  305;  figure  of, 

305 


Cutting,  calloused  end  of,  figure  of,  377 

Cutting  frozen  material,  656 

Cuttings   of   Populus   pyramidalis,  379 

Cyathus,  245 

Cyclochorisis,  334 

Cylindrosporium  padi,  266 

Cj'stobacter,  40 

Cystopus  condidus,  74 

Cytase,  58     . 

Cytinus  hypocistus  as  a  parasite,  301 

Cytisus  Adami,  a  graft  hybrid,  329,  330 

Cytology,  emphasized,  271;  of  fleshy 
fungi,  218;  of  rusts,  191 

Cytoplasm  in  bacteria,  23 

Cyttaria  Berterii  in  Patagonia,  85; 
Darwinii  in  Patagonia,  85;  Gunnii  in 
Tasmania,  85;  Harioti  in  Terra  del 
Fuego,  85;  in  southern  Patagonia, 
74;  on  Nothofagus,  171 

Cyttariace^e,  characters  of,  171 


D 


Dacryomycetaceae,  characters  of,  219 

Dffidalea  quercina,  558;  absorption  of 
phosphorus  by,  54;  figure  of,  558; 
occurrence  of,  230 

Damping-oflf,  342;  distribution  of  fun- 
gus, 84 

Danilov,  work  on  lichens  mentioned,  78 

Dasyscypha  Willkommii,  519 

Death  of  hosts,  314 

Decapitation  experiments,  376 

De  Bary,  Anton,  work  of,  189;  men- 
tioned, 7 

Decay,  33;  of  maple,  523;  of  oak,  526; 
of  timber,  553 

Decoctions,  plant,  600 

Dedoublement,  334 

Deformation,  334 

Degeneration,  334 

Delafield's  haematoxylin,  590 

Deliquescence  of  Coprinus  comatus,  65 

Destruction  of  organs,  348 

Description  of  methods  of  bacterial 
study,  631,  639 


760 


INDEX 


Desiccation,  566 

Determining  cause  of  disease,  274 

Detailed  account  of  specific  plant 
diseases,  475  et  seq. 

Deuteromycetes,  258-269 

Developmental  mechanics  of  pathologic 
tissues,  bibliography  of,  405,  406,  407 

Development  of  carrion  fungi,  248;  of 
fruit  bodies  in  mushrooms,  235,  236 

De  Vries,  Hugo,  work  of,  331 

Dextrose,  58 

Diachaena  strumosa,  74 

Diagram  of  rust  spore  relations,  190 

Dialysis,  334;  of  enzymes,  57 

Diaphysis,  334 

Diastase,  58 

Dictydin  granules,  15 

Dictydium,  15 

Dictyophora  duplicata,  figure  of.  249; 
origin  of  veil,  249,  250;  phalloidea, 
figure  of,  250;  figure  of  structure,  251 

Dictyostelium  mucoroides,  8 

Dictyonema,  a  lichen,  81 

Didymium  melanospermum,  spore  for- 
mation in,  13,  14 

Die-back  of  citrus  fruits,  572 

Dilution  methods,  616 

Diplasy,  335 

Diplodia  zeae,  504 

Diploid  chromosomes  in  slime  moulds,  16 

Diremption,  335 

Diruption,  335 

Discentration,  335 

Discharge  of  spores,  233,  234;  figure  of, 
63;  in  mushroom,  figure  of,  64 

Discoloration,  342,  343 

Discomycetiineae,  characters  of,  164,  165 

Diseases,  list  of  common  plant,  414-473 

Diseases,  non-parasitic,  564 

Diseases  of  plants,  bibliography  of  speci- 
fic, 473-474 

Diseases  of  plants  in  general,  271;  two 
groups  of,  413 

Diseases  of  sweet  pea,  647 

Disease  prevention,  bibliography  of,  318; 
resistance,  325 


Disinfection,  692 

Displacement,  335 

Dissemination  of  fungi,  314,  315 

Distribution  of  slime  moulds,  18 

Distrophy,  335 

Dittschlag,  work  of,  on  rusts,  191 

Divulsion,  335 

Dodder,  figure  of,  305;  figure  of  section 

of,  306;  study  of,  651 
Dodge,  B.  O.,  cited,  13,  15 
Dormant  fungus  in  seeds,  308 
Dorrance,  Frances,  translations  by,  413, 

564 
Dothideaceae,  characters  of,  162 
Downy  mildew  of  grape,  513 
Downy     woodpecker      and     spores     of 

Endothia  parasitica,  67 
Drawing  apparatus,  657 
Drawing  suggestions,  664-668 
Drop  of  lettuce,  522 
Dropsy,  352 
Dry  rot,   343;   of  corn,   504;   of  larch, 

519;  of  potato,  543 
Dry-rot  fungus,  225;  in  timber,  553 
Duggar,    B.    M.,    book    on    mushroom 

growing,  237 
Duration  of  disease,  313 
Dust  brand,  178 
Dwarfing,  342,  346 


Earth-star,  239,  244 

Ecblastesis,  335,  338 

Ecology  of  fungi,  69 

Economic  entomology,  field  of,  296 

Ectotrophic  mycorhiza,  figure  of,  49 

Edinger's  drawing  apparatus,  figure  of 
details,  660,  661;  description  of,  657- 
664 

Egg  albumen,  603;  yolk,  603 

Egg  plant  wilt,  646 

Elaphomycetaceae,  character  of,  150 

Elaphomyces,  character  of  various  spe- 
cies, 150 

Elaters  in  slime  moulds,  15 


INDEX 


761 


Eleagnus,  9 

Electric  arc  and  fungi,  62 

Elenkin  work  on  lichens  mentioned,  78 

Embryology  emphasized,  271 

Empusa  muscae,  description  of,  104; 
figure  of,  104;  as  fly  cholera,  85 

Emulsin,  58,  59 

Enation,  335 

Enerthenema  papillatum,   figure  of,  14 

Endocellular  enzymes,  56 

Endomycetaceae,  characters  of,  131 

Endomyces  decipiens,  parasitic  on  Armil- 
laria  mellea,  131 

Endophyllaceae,  characters  of,  198 

Endophyiium  sempervivi,  described,  196, 
198;  on  house  leek,  348 

Endophytic  mycelium,  48 

Endospores  in  bacteria,  25 

Endothia  parasitica,  491;  and  downy 
woodpecker,  67;  description  of,  164; 
distribution  of,  83,  84;  figure  of  peri- 
thecial  pustules,  493, 495 ;  mycelium  of, 
496;  spread  of,  316 

Engelmann  experiment  with  bacteria 
and  oxygen,  27 

Engler  cited,  2 

Enteridium  splendens,  pink  Plasmo- 
dium of,  12 

Entomology  emphasized,  271 

Entomophthoraceae,  characters  of,  103 

Entomosporium  maculatum,  264 

Entyloma,  description  of  several  species, 
185 

Enumeration  of  means  of  fungous 
entry  into  plants,  312 

Enzymes,  56;  and  heat  57;  and  liquid 
air,  57;  and  plant  diseases,  326;  carbo- 
hydrate splitting,  58;  classification  of, 
58;  clotting,  59;  definition  of  word, 
56;  detection  of,  59;  diseases,  650; 
distribution  in  fungi,  58;  fat  splitting, 
59;  fermenting,  59;  glucoside  split- 
ting, 59;  oxidizing,  59;  protein-split- 
ting, 59;  solubility  of,  57;  urea-split- 
ting, 59 

Epanody,  335 


Epipedochorisis,  335 

Epidemics,  315 

Epiphytic  mycelium,  48 

Epiphytotisms,  298,  315 

Epistrophy,  335 

Ergotin,  56 

Ergot  of  rye,  546 

Eriksson's  mycoplasm,  190 

Erysiphaceae,  characters  of  family,  154; 
Key  to  genera  of,  721,  722 

Erysiple,  Key  to  species  of,  723 

Escape  of  swarm  spores,  67 

Esterases,  59 

Ether  freezing  attachment,  figure  of,  659 

Etiolated,  335;  plants,  277;  plants 
hypertrophied,  366 

Etiolation,  360;  experiments  with,  652 

Etiology,  272;  description  of,  641,  of 
galls,  385 

Eubacteriales,  34 

Eubasidii,  218;  bibliography  of,  252-257 

Eumycetes,  i,  42,  45,  46 

Euphrasia  as  a  root  parasite,  299 

Exanthema  of  citrus  fruits,  572 

Excrescences,  342,  348;  of  bark,  366 

Excursions  suggested,  667 

Exoascus  and  witches'  brooms,  72;  de- 
scription of  species,  133,  134;  figures 
of,  132 

Exoascus  cerasi,  491;  deformans,  534; 
pruni,  74,  541 

Exoascaceae,  characters  of,  131 

Exobasidiaceas,  characters  of,  220 

Exobasidium,  distribution  of  species  and 
their  hosts,  86,  87;  vaccinii,  figure  of, 
220;  various  species  described,  220 

Expansivity,  335 

Explosions  of  smut,  182 

Extracellular  enzymes,  56 

Exudations,  343,  350 

Eyebright  as  root  parasite,  299 

Eyepiece  micrometer,  582 


Fabre,  J.  H.,  cited,  71 

Facultative  parasite,  42;  saprophyte,  42 


762 


INDEX 


Fairy  ring,  figure  of,  75,  735;  fungus,  74; 
toadstool,  735 

Fasciation,  329,  335 

Fats  in  fungi,  53,  56 

Fat-splitting  enzymes,  59 

Faull,  J.,  work  of,  172 

Fermenting  power  of  yeasts,  595;  en- 
zymes, 59 

Ferments,  56 

Fermentation,  acetic  acid,  32;  alcoholic 
in  yeasts,  138;  butyric,  32,  59; 
by  bacteria,  32;  by  mould,  96;  in 
yeasts,  137;  in  fungi,  307;  lactic  acid, 
32,  59 

Ferrobacteria,  28 

Field  of  economic  entomology,  296 

Field  trip  suggestions,  667 

Figure  of  rod-shaped  bacteria,  22 

Filar  micrometer;  figure  of,  583 

Film  formation  in  yeasts,  137 

Final  outcome  of  disease,  314 

Fingers  and  toes,  487 

Fink,  Bruce,  quoted,  78 

Fire-blight  of  pear,  536 

Fission,  336 

Fistulina  hepatica,  230;  on  tree  trunks, 

83   _ 

Fistulinoideas,  230 

Fixatives,  655 

Flagella  of  slime  moulds,  16 

Flecks  of  pith,  294 

Fleshy  fungi,  218  et  seq. 

Flies  and  spore  distribution,  67 

Flowers  of  tan,  17 

Flowering  plants  as  cause  of  disease,  275 

P'luckiger  mentioned,  56 

Fogs,  influence  of,  284 

Foliose  lichens,  79 

Fomes  applanatus,  313;  fomentarius, 
523;  figure  of,  229;  fraxinophilus, 
figures  of,  481,  482;  on  beech,  figure 
of,  524;  igniarius,  figure  of,  554; 
of  rot  by,  555,  556 

Forms  of  rust  life  cycles,  189 

Fossil  fungi,  82 

Fraser,  Miss  H.  C,  work  on  rusts,  191 


Free,  E.  E.,  work  of,  407 

Freezing  attachment  for  microtome, 
figure  of,  657 

Freezing  material,  656,  657;  micro- 
tome, figure  of,  658 

Fries  mentioned,  7 

Frondescence,  336 

Frost  cracks,  294;  influence  of,  283; 
necrosis  of,  569 

Fruit-pit  of  apples,  570 

Fruit-rot  of  orange,  533 

Fruticose  lichens,  79 

Fuhrmann,  F.,  cited,  22,  24 

Fuligo  septica,  as  flowers  of  tan,  17; 
yellow  Plasmodium,  12 

Fuligo,  spore  formation  in,  14 

Fungi  as  cause  of  disease,  306,  307;  as 
disease  producers,  275 

Fungicides,  definition  of  terms,  669 

Fungi  imperfecti,  characters  of,  258- 
269 

Fusarium  batatatis,  figure  of,  267; 
heterosporium,  61;  hyperoxysporum, 
figure  of,  267;  lycopersici,  646; 
putrefaciens,  infection  by,  273;  species 
of,  267,  269;  trichothecoides,  543, 
643;  violae,  figure  of,  268 


Galactose,  58 

Gallionella,  37 

Galls,  342,  348,  384  et  seq.;  aeration 
tissues,  400;  animal,  296;  and  insect 
producers,  396;  assimilation  tissues  of, 
400;  bibliography  of,  401,  402; 
cataplasmic,  385;  formation,  72;  his- 
tology of,  396,  397;  hyperplasia,  384; 
hypertrophy,  370,  371,  384;  mechanic 
tissue  of,  398;  nutritive  tissue  of, 
398;  of  cranberry,  509;  protective 
tissues,  398;  secretory  reservoirs  of, 
400;  vascular  tissues  of,  400 

Gamomery,  336 

Gangrene,  343,  352 

Gas  injuries,  649 


763 


Gases,  efifect  of,  289 

Gasteromycetes,  character  of,  239,  240 

Geaster,  239,  244 

Geaster     fornicatus,     figure     of,     243; 

hygrometricus  in  sandy  soil,  83 
Gelatin,  nutrient,  604 
Gelatin,  sugar,  604 
Gelatinous  threads  of  chestnut   blight, 

figure  of,  494 
Gemmiparity,  336 
Genera  of  smuts,  182 
Genetics  emphasized,  271 ;  nature  of,  271 
Gentian   violet,   Ehrlich's   anilin-water, 

589 
Geoglossaceae,  description  of,  169 
Geoglossum  glutinosum,  170;  hirsutum, 

169;  figure  of,  170;  range  of,  85 
Geographic  distribution  of  fungi,  82 
Gerardia  as  a  root  parasite,  299 
Germination  of  smut   chlamydospores, 

507;  of  smut  spores,   181;  of  spores, 

61;   of   spores   and   bacteria,    25;    of 

spores  of  slime  moulds,  16 
Germination  studies,  615 
Gerry,  Eloise,  work  on  tyloses,  370 
Giant  cells,  371 
Gilg  cited,  2 
Gilson,  research  of,  52 
Ginger  beer,  140 
Girdling  of  trees,  295 
Glanders,  35 

Gloeosporium  venetum,  544 
Glomerella  cingulata,  477,  478;  gossypii, 

508;  rufomaculans,  264,  477,  478 
Glucose,  53,  59 

Glucoside-splitting  enzyme,  59 
Glycine   hispida,   figure   of   nodules   on 

roots,  29 
Glycocol,  S3, 
Glycogen  in  fungi,  53 
Gnomonia    veneta,    163,    264,    549;  on 

plane,  85 
Graft  hj^brids,  329 
Grape,  512 

Graphis  scripta  on  bark,  83 
Gram's  stain,  590 


Gray  mould,  figure  of,  42 

Green  mould  described,  45 

Griffiths,  David,  work  cited,  163 

Grove,  W.  B.,  book  of,  189 

Guenther  mentioned,  54 

Guignardia  Bidwellii,  512;  of  grape,  163; 
vaccinii,  509;  figure  of,  510 

Guillermond,  M.  A.,  work  cited,  142 

Gummosis,  343,  350 

Guttulina  rosea,  8 

Guying,  323     • 

Gymnaxony,  336 

Gymnoascaceae,  characters  of,  143 

Gymnoconia  interstitialis,  figure  of,  202 

Gymnosporangium  biseptatum,  figure 
of  swelling  caused  by,  347;  clavariae- 
forrrte,    mycocecidia    of,    393;    Ellisii 

73,  210;  figure  of,  205;  globosum,  21c; 
Gymnosporangium   juniperi-virginianae, 

74,  2 1 1-2 14;  mycocecidia,  393;  species 
of,  208-210 

Gynophylly,  336 

Gypsum  blocks  and  yeast  spores,  622 

Gyromitra,  171 


Hackberry,  witches'  broom,  73,  351 
Haas,  Paul,  book  of,  57 
Haeckel,  Ernst,  cited,  7 
Haematimeter,    Thoma's,    617;    details 

of,  619 
Hail  and  plants,  286 
Hailstones,  bruises  by,  294 
Hanbury,  487 

Hanging-drop  preparations,  587 
Hansen,  E.  Chr.,  work  of  mentioned,  32, 

141 
Haploid  chromosomes  in  slime  moulds, 

16 
Happy  white  elm,  figure  of,  286 
Hard  pan,  influence  of,  281 
Harper,  R.  A.,  cited,  13,  15,  112,  165 
Harshberger,  John  W.,  observations  on 

acid  spotting  of  morning-glories,  293; 

work  of,  308;  on  pine-barrens,  281;  on 

white  cedar  fungi,  394 


764 


Haustoria,  48;  of  Erysiphaceaj,  155 

Hay  bacillus,  36 

Heald,  F.  D.,  work  of,  342 

Heart-rot  of  ash,  481,  483;  of  hemlock, 

517 
Heat  as  factor  in  plant  disease,  282 
Helotiacese,  characters  of,  168 
Helvellaceas,  characters  of,  170 
Helvella  crispa,  171;  esculenta,  fat  con- 
tent, 56 
Helvelliineae,  a  suborder,  169 
Hemibasidii,  178 
Hemileia  vastatrix,  503 
Hemlock,  517 

Hemisyncotylous  races,  329 
Hemitery,  336 
Hemitrichia  vesparum,  plasmodium  of, 

12 
Hepatica   triloba  attacked   by  Tranzs- 

chelia  punctate,  348;  figure  of,  349 
Hepburn's  definition  of  enzyme,  56 
Herbivores  and  spore  distribution,  66 
Heterodera  radicicola,  391,  651 
Heterogamy,  336 
Heteromorphy,  336 
Heteroplasia,  374,  375 
Heteroplasm,  correlation,  376 
Heterotaxy,  336 
Heterothallic  moulds,  93 
Hill,  T.  G.,  book  of,  57 
Histology  emphasized,  271 
Histology  of  callus,  379;  of  cataplasms, 

391;  of  fungi,  52;  of  galls,  396,  397 
Histozyme,  58 
Hollyhock,    517;    rust,    203,    206,    517; 

figure  of,  518 
Homooplasia,  374,  375 
Homothallic  moulds,  93 
Homotypy,  336 
Horses,  injury  by,  310 
Host  list  of  oomycetous  fungi,  115 
Humphrey,  C.  T.,  mentioned,  75 
Humus,  influence  on  plants  of,  281 
Hydnaceae,  characters  of  family,  223 
Hydnocystis  arenaria  and  black  beetle, 

71 


Hydnoraceae,  parasites  of,  299 

Hydnum  erinaceus,  figure  of,  224,  556 

Hydnum,  species  of,  223 

Hydrocyanic  acid,  59 

Hymenium,  232 

Hymenogastraceae,  character  of  family, 

240 
Hymenomycetes,  characters  of,  219 
Hyperchimaeras,  330 
Hyperhydric  tissues,  366 
Hyperplasia,  355,  373 
Hypertrophy,  337,  347,  354,  364  et  seq.; 

kinds  of,  364 
Hyphas,  42 

Hyphomycetales,  characters  of,  266 
Hypochnaceae,  characters  of,  220 
Hypocreaceae,  characters  of,  160 
Hypomyces,    range    of    species    of,  85; 

lactifluorum  parasitic  on  Lactarius,  1 60 
Hypoplasia,  354,  357;  and  cell  contents, 

359,   and   tissue  differentiation,   360; 

number  of  cells,  357;  size  of  cells,  358 
Hypothallus,  13 
Hypoxylon,  164 
Hysteriaceae,  characters  of,  165 


Ice  action,  295 

Ice   fringes,   their  formation,    283,    284 

Ice  load  of,  figured,  285 

Ice  storm  and  trees,  284,  285,  286 

Iceland  moss  on  ground,  83 

Icterus,  343 

Idiotery,  337 

Illuminating  gas,  effect  of,  291,  292 

Immunity,  272,  325;  to  plant  disease, 
274 

Impregnation  of  wood  with  preserva- 
tives, 692 

Indol,  33 

Incubation,  312 

Incubator,  copper,  612 

Infection  by  fungi,  307 

Infusions  of  plants,  600 

Injured  tree,  figure  of,  309 


765 


Injuries  by  acid,  649;  by  gas,  649;  by 
smoke,  649 

Inoculation  experiments,  643  et  seq. 

Inorganic  elements  in  fungi,  55 

Insecticides,  678,  679 

Insects  as  cause  of  disease,  275;  as  gall 
producers,  396;  biting,  296;  sucking, 
296;  wood-boring,  310 

Intercellular  hyphae,  48 

Internal  causes  of  disease,  326 

Intucellular  hyphae,  48 

Intumescences,  366 

Inulin,  58 

Inulase,  58 

Invertase,  58 

Involution  forms  of  Bacillus  radicicola, 
30;  of  bacteria,  364;  of  Pseudomonas 
tumefaciens,  365 

Iron  indispensable  to  fungi,  54;  in- 
fluence of,  277 

Irpex,  species  of,  223,  224 

Isolation  of  fungi  in  pure  culture,  624 

Ithyphallus  impudicus,  252;  and  flies,  67 


fleshy  fungi,  list  of,  729-732;  to  genera 
of  family  Exoascaceae,  133;  to  genera 
of  Peronosporaceae,  114;  to  Myxogas- 
trales,  693-695;  to  Nidulariaceae, 
244,  245;  to  species  of  Penicillium 
on  agar  and  gelatin,  712-719;  to 
suborders  of  Basidiomycetales,  177 

Kiln-drying,  693 

Kinase,  57 

Kinds  of  lichen  thalli,  79 

Koernicke,  Max,  experiments  with 
Roentgen  rays,  62 

Kohlhernie,  487 

Koji  fungus,  58 

Kolkwitz,  experiments  of,  62 

Knauers,  348 

Knife  punch,  figure  of,  597 

Knot  of  citrus  trees,  experiments  with, 
647 

Kuehneola  gossypii,  508 

Kiihne,  mentioned  with  enzymes,  56 

Kurssanow,  work  on  rusts,  191 


J 


Jahn,  E.,  cited,  13 

Jeffer's  counting  plate,  628;  figure  of,  629 

Jew's  ear  fungus,  216 

Jones,  L.  R.,  work  on  cabbage  immunity, 

274 
Juniperus  virginiana,   cedar  apples  'on, 

394 


K 


Kapoustnaja  kila,  487 

Karyokinesis,  in  fungi,  53 

Kephir,  58,  140 

Kerner,  Anton,  work  of,  385 

Key  to  determine  species  of  Mucor, 
695-702 

Keys  to  Erysiphaceas,  mentioned,  157 

Key  to  families  of  Oomycetales,  109; 
to  families  of  Perisporiineae,  154;  to 
families    of    Zygomycetales,    97;    to 


Laboratory  exercises,  581;  with  slime 
moulds,  18 

Laboulbeniaceae,  172;  hosts  of,  86; 
work  of  Faull  on,  173 

Laboulbeniineae,  171 

Labyrinthula  Cienkowskii,  11 

Lachnea  description  of  several  species, 
169;  scutellata,  figure  of,  166 

Lactarius,  731;  chelidonium,  description 
of,  740;  deceptivus,  description  of, 
740;  deliciosus,  description  of,  740; 
description  of  genus,  740;  fumosus, 
description  of,  741;  piperatus,  de- 
scription of,  741;  indigo,  description 
of,  741;  volemus,  description  of,  742 

Lactic  acid  fermentation,  32,  59 

Lactase,  58 

Lactose,  58,  59 

Lamium  orvala,  figure  of,  callus,  378 

Lamprocystis,  39 

Lantz,  Cyrus  W.,  bibliography  by,  564 


766 


INDEX 


Larch,   519;  canker,   168,  519;  dry-rot, 

519 
Late-blight  of  potato,  542 
Lathraea  squamaria  as  a  root  parasite, 

299 
Lathrop,  Elbert  C,  worii  of,  33 
Laticiferous  hyphae,  48 
Laudatea,  a  lichen,  81 
Leaf-blotch  of  maple,  523 
Leaf-casting,  575 

Leaf-curl  of  cherry,  491;  of  peach,  534 
Leaf-mildew  of  chestnut,  502 
Leaf-spot  of  alfalfa,  476,  477;  of  apple, 

figure  of,  344;  of  beet,  484,  485;  of 

coffee,  503;  of  violet,  figure  of,  559 
Leaves,  skeleton,  294 
Leguminous  tubercles,  387 
Leocarpus  fragilis,  figure  of,  17 
Leotia  chlorocephala,  170;  lubrica,   170 
Lepidophyton,  147 
Lepidosaphes  ulmi,  figure  of,  276 
Leptothrix,  37;  ochracea,  29 
Lepyrophylly,  337 
Lemon,  520 

Lenticels,  hypertrophied,  366 
Lenzites    betulina,    64;    occurrence    of, 

230;  sepiaria  and  rotting  of  slash,  75 
Lettuce,    522;    drop,    522;    experiments 

with,  644 
Leucin,  33 

Leuconostoc  mesenterioides,  34 
Levulose,  58,  59 
Liberation   of   spores,   62;   in  Coprinus 

comatus,  65 
Lichen  thalli,  79;  algae,  78;  as  fungi,  79; 

parasitism  of  fungi,  79;  nature  of,  78; 

structure  of  thallus,  81 
Life  cycle  of  Oomycetales,  diagram  of, 

108;    of    Pyronema    contrasted    with 

fern,  126 
Life  histories,  description  of,  641 
Light    and    pathologic    conditions,    ex- 
periments, 652 
Light  and  red  pigment,  360;  influence 

of,  61,  281;  action  of,  288,  289 
Lightning,  injury  by,  311 


Lilac,  522;  mildew,  522 

Lime-sulphur,  675-677 

Linaria  vulgaris,  peloria  of,  329 

Lindau,  G.,  mentioned,  171 

Lipase,  58,  59 

Liquid  nutrient  solutions,  592-595 

List  of  common  plant  diseases,  414-473; 
of  keys  to  fleshy  fungi,  729-732 

Lister,  A.,  work  of  mentioned,  18 

Literature  of  plant  diseases,  exercises 
in  compiling,  642;  on  tree  surgery,  324 

Litmus  milk,  600;  whey,  600 

Living  organisms  as  cause  of  disease,  275 

Locomotion  of  bacteria,  23 

Lohden wedge,  379 

Long,  W.  H.,  mentioned,  75 

Lophotrichous,  23 

Loranthaceae,  parasites  of,  301 

Lotsy,  P.,  work  on  sexuality  of  As- 
comycetales,  122 

Luminosity  of  fungi,  62 

Lumpjaw  of  cattle,  39 

Lupinus  angustifolius,  figure  of  cross- 
section  of  tubercle,  30,  387,  388 

Lycogala  epidendrum,  plasmodium  of,  17 

Lycoperdaceae,  character  of  family,  241 

Lycoperdon,  species  of,  241,  242 


M 


MacBride,  Thomas  H.,  work  of  men- 
tioned, 18 

MacDougal,  D.  T.,  experiments  with 
fungi  in  dark,  61 

Macrodactylis  subspinosus,  figure  of,  275 

Macrosporium  solani,  266,  267 

Magnesium,  influence  of,  277 

Magnification  values,  tables  of,  663 

Maladie  digitorie,  487 

Malaria,  18 

Malformations,  329,  342,  348 

Malpighi,  385 

Maltase,  58 

Maltose,  58 

Manihot,  oedema  of,  567 

Mannite,  53 


INDEX 


767 


Mannose,  58,  59 

Manual    of    American    boletes,  227;  of 

polypores,  227 
Maple,  523;  decay,  523;  leaf-blotch,  523 
Map  of  chestnut  blight  fungus,  84 
Marasmium  oreades,  74;  figures  of,  75, 

735 

Massee,  George  A.,  book  of,  91;  men- 
tioned, 169 

Masters,  Maxwell  T.,  331,  340 

Matzoon,  141 

Mazum,  141 

McAlpine,  D.,  work  of,  570,  571 

Mechanic  development  of  pathologic 
tissues,  403,  404,  405 

Mechanic  injury,  294 

Mechanic  tissue  in  galls,  398 

Mechanics  of  pathologic  tissues,  bibliog- 
raphy of,  405,  406 j  407 

Meiophylly,  337 

Meiotaxy,  337 

Melampsoraceae,  characters  of  family, 
198 

Melampsora,  species  of,  199 

Melampsoropsis,  species  of,  199 

Melampyrum  as  a  root  parasite,  299 

Melanconiales,  characters  of,  264 

Meliola  camelliae,  54;  distribution  of, 
85;  Penzigi,  521 

Melitiose,  58 

Melogrammataceae,  characters  of,  164 

Melon  anthracnose,  525;  wilt,  525 

Merulius  lacrymans,  553;  description  of, 
224,  225,  226;  figure  of,  225,  226 

Meruloideae,  224 

Meschinelli,  L.,  work  on  fossil  fungi,  82 

Mesospores,  188 

Mespilodaphne  sassafras,  section  of  old- 
wood,  figure  of,  369 

Metal-covered  cavities,  323 

Metamorphosis,  337 

Metaphery,  337    . 

Metaplasia,  354,  362  et  seq.;  and  cell 
contents,  362;  and  cell  membranes, 
363 

Metastasis,  337 


Metatrophic  bacteria,  31;  organisms,-  28 
Meteorologic  factors  of  disease,  281 
Methods  of  teaching,  407-410 
Methylene  blue,  alkaline,  589 
Meyer,  mentioned,  54 
Micrococcus,  34;  aurantiacus,  34;  cinna- 

bareus,    34;   gonorrhoeae,   34;    luteus, 

34;  progrediens,  diameter  of,  21,  22; 

pyogenes  aureus,  34;  ureae,  diameter 

of,  22;  with  urease,  59 
Micrometer,   eyepiece,    582;   filar,   583; 

figure  of,  583;  stage,  582;  step,  585; 

figure  of,  586;  tables  of  values,  584, 

585 
Micrometry,  582 
Microsphaera  alni,  522;  figure  of,   157; 

key  to  species  of,  724,  725 
Microspira,  37 
Microtome,  figure  of  sliding,  654;  with 

freezing  attachment,  figure  of,  658 
Microthyriaceae,    characters   of   family, 

158 
Mildew  of  grape,  figure  of,  515 
Milk,  600;  litmus,  600 
Mischomany,  337 
Miso  sauce,  146 
Mistletoe  diagram  of  habit,  304;  figure 

of,  302,  303;  references  to  literature, 

304;  study  of,  651 
Mites,  296 

Mixing  of  cement,  321 
Miyoshi,  M.,  experiments   with  chemo- 

taxis,  60 
Mnium      hornum      and      underground 

truffles,  71 
Molisch,    Hans,    experiments    of,    62; 

mentioned,  54 
Mollisiaceae,  characters  of,  169 
Monoblepharidaceae,  characters  of,  109 
Monoblepharis   sphaerica,   structure   of, 

109 
Monospora,  141 
Monosy,  337 
Monotrichous,  23 
Monstrosities,  329 
Moore,  Geo.  T.,  work  of,  31 


768 


Morchella,  170,  171;  esculenta,  analysis 
of,  55 

Morel,  170,  171 

Morphology  emphasized,  271;  of  bac- 
teria, descriptive  terms,  633;  of 
chestnut  blight  fungus,  497 

Mortierellaceae,  characters  of  family,  103 

Mortification  of  tissues,  346 

Mosaic  diseases,  327 

Mosaic  of  bean,  577;  of  tobacco,  578 

Mottle-leaf,  573 

Mould  fungi,  92;  sexual  reproduction,  93 

Mounting  bacteria,  588 

Movement  of  Plasmodium,  12 

Mucoraceae,  character  of,  97 

Mucor,  figure  of,  42;  key  to  species, 
695-702;  mucedo,  chitin  in,  52;  de- 
scribed, 45;  figure  of,  44;  occurrence 
of,  83;  sporangia  of,  96;  structure  of, 
98;  racemosus,  chitin  in,  52;  Rouxii  as 
Chinese  yeast,  99;  various  species 
of,  98 

Multinucleate  cells,  372;  giant  cells, 
371;  spores  of  Rhizopus  nigricans,  96 

Multiplication,  337 

Mummification,  342,  347 

Miinch,  E.,  experiments  on  water  and 
air  content  of  tissues,  280 

Murrill's  arrangement  of  fleshy  fungi, 
228 

Muscaria,  56,  238 

Mushrooms,  231;  chemistry  of,  237; 
cultivation  of,  236,  237,  693;  develop- 
ment, 235,  236;  figures  of,  234,  746; 
toxicology,  237,  238,  239 

Mutations,  328 

Mutinus  caninus,  development  of,  248, 
249;  and  flies,  67 

MyceHum,  42;  of  Endothia  parasitica, 
figure  of,  496 

Mycetozoa,  7 

Mycocecidia,  393 

Mycodendron  paradoxum,  226 

Mycoderma  aceti,  59;  nature  of,  142 

Mycomycetes,  46,  120 

Mycoplasm,  49;  Eriksson's,  190 


Mycorhiza,  49 

Mylitta  australis,  sclerotium  of,  71 

Myriangiaceas,  153 

Myrica  carolinensis,  tubercles  on  roots, 

39 
Myxamoebae,  15 
Myxobacter,  40 
Myxobacteriaceae,  21,  39 
Myxococcus,  40 
Myxogastrales  characters  of,  11;  key  to, 

693-695 
Myxogastres,  7 
Myxomycetes    i,  7 


N 


Nanism,  346 

Nature  of  tree  surgery,  320 

Necrosis,    342,    346;    frost,    of    potato 

tubers,  569 
Nectria  cinnabarina,  description  of,  160 
Nectria,  figures  of  various  species,   159 
Neisser's  counting  apparatus,  629 
Nematode  infection,  651;  worms  as  gall 

formers,  391 
Neocosmospora  vasinfecta,  646 
Neoepigenesis,  404 
Neoevolution,  404 
Nidularia,  244 
Nidulariaceae,  character  of  family,  244; 

key  to,  244,  245 
Nitric  organism,  isolation  of,  611 
Nitrifying  bacteria,  29 
Nitrobacter,  29 
Nitrogen  cycle,  ^y,  deficiency,  influence 

of,  278;  fixation,  612;  influence  of,  278; 

source  of  in  fungi,  55 
Nitrococcus,  29 

Nitrosomonas,  29;  javanensis,  29 
Nodule-forming  bacteria,  29 
Nodules  of  roots,  387 
Non-parasitic  diseases,  564;  bibliography 

of,  580 
Normal  solutions,  613 
Nothofagus  with  Cyttaria,  74 


769 


Nuclear  apparatus  of  yeasts,  135;  divi- 
sion in  yeasts,  136;  phenomena  in 
fleshy  fungi,  218;  in  rusts,  192,  193; 
phenomena  of  fleshy  fungi,  students 
of  problems,  218,  219 

Nuclease,  58,  59 

Nuclei  in  fungous  cells,  53 

Nucleus  in  bacteria,  23 

Number  of  spores  produced,  63 

Nummularia  BuUardi  on  beech  branches, 
164 

Nutrient  solutions,  592-595 

Nutrition  of  bacteria,  classification  ac- 
cording to,  28 

Nutritive  disturbance  as  cause  of  disease, 
328;  tissues  in  galls,  398 

Nyctalis  asterophora,  parasitic,  on 
Russula  nigricans,  figure  of,  43 


Oak,  526;  decay,  526;  root-rot,  530 

Oat,  531;  rust,  531;  crown  rust  of,  202 

Obligate  parasite,  42;  saprophyte,  42 

Qidema,  352;  of  manihot,  567;  figure  of, 
568 

Oenothera  Lamarckiana,  328 

Oidiospores,  50 

Oidium  lactis  in  Matzoon,  141 

Oils  in  fungi,  53,  56 

Olive,  Edgar  W.,  work  on  rusts,  191; 
cited,  13 

Onion,  531;  smut,  531 

Oochytrieae,  117 

Oolysis,  337 

Oomycetales,  43,  50;  bibliography  of, 
118,  119;  characters  of,  107;  key  to 
families,  109;  motile  cells  in,  52; 
occurrence  of,  108;  sexual  reproduc- 
tion in,  107 

Oomycetous  fungi,  host  list,  115 

Oospora  scabies,  occurrence  of,  83 

Oospores,  50 

Orange,  533;  black-rot,  533^  fruit-rot, 
533;  juice,  598 

Orobanchaceae,  parasites  of,  299 


Orobanche,  as   a   parasite,  299;  minor, 

figure  of,  300 
Organized  ferments,  56 
Orton,  W.  A.,  on  quarantine,  317 
Osmomorphosis,  404 
Ostwald,  mentioned,  57 
Oyster  mushroom,  738 
Oyster-shell  scale,  figure  of,  276 
Oxidizing  enzj'mes,  59 


Pachyma  cocos,  72;  malacense,  sclero- 

tium  of,  72 
Pallor,  342 
Panaschiering,  326 
Parachromatophorous,  26 
Paraffin  method,  656 
Paralyzers,  57 
Parasite,  42;  chlorophylless,  298;  green, 

298;  on  roots,  299 
Parasitic  algae,  391 
Parasitism  of  lichen  fungi,  79 
Paratrophic  bacteria,  33;  organisms,  28 
Parmelia    perlata,     figure    of,     80;    on 

trunks  of  trees,  83 
Pasteurization,  625 
Pasteur  mentioned,  56 
Patellariacese,  169 
Pathogenic  fungi,  study  of,  639 
Pathologic  plant  anatomy,  354;  tissues, 

mechanic  development  of,  403,  404, 

405 
Pathologist,  character  of  work  of,  341 
Pathology,  special  plant,  411  et  seq. 
Patterson,  Flora  W.,  bulletin  of,  244 
Pea,  534;  pod-spot,  534 
Peach  leaf  cure,  534;  yellows,  315,  573 
Pear,    536;    blight,    experiments    with, 

644,  figure  of  experiment,  645 
Peloria,  329,  337 
Peltigera  canina  on  ground,  83 
Penicillium    atramentosum,    figure    of, 

713;  bif orme,  figure  of ,  7 1 6 ;  brevicaule, 

description   of,    709;    figure   of,    709; 

Camemberti,  description  of,  706,  707; 

figure    of,    706;    chrysogenum,    711; 


770 


claviforme,  figure  of,  710;  commune, 
figure  of,  717;  decumbens,  figure  of, 
715;  digitatum,  figure  of,  720;  Du- 
clauxii,  figure  of,  711;  expansum, 
figure  of,  704;  funiculosum,  figure  of, 
714;  general  characters  of,  703; 
glaucum,  61;  chitin  in,  52;  described, 
45;  figure  of,  46;  with  lipase,  59; 
italicum,  533;  figure  of,  708;  key  for 
species  on  various  substrata,  719,  720; 
key  to  species  grown  on  agar  and 
gelatin,  712,  719;  lilacinum,  figure  of, 
713;  purpurogenum,  figure  of,  719; 
Roqueforti,  description  of,  704;  figure 
of,  705 ;  roseum,  figure  of,  712;  rubrum, 
figure  of,  718;  rugulosum,  figure  of, 
721;  spinulosum,  figure  of,  718; 
stoloniferum,  description  of,  708; 
figure  of,  707 

Penzig,  O.,  work  of,  331 

Pepsin,  59 

Periclinal  chimjeras,  330 

Peridermium,  188;  species  of,  201; 
strobi,  537 

Periphyllogeny,  337 

Perisporiaceas,  characters  of  family,  158 

Perisporiineae,  characters  of,  154;  key 
to  families,  154 

Perithecium,  structure  of,  121 

Peritrichous,  23 

Permutation,  337 

Peronosporacea?,  cellulose  in,  52;  charac- 
ters of  family,  in;  generic  key,  114 

Peroxidase,  59 

Pestalozzia   Guepini  var.   vaccinii,   266 

Petalody,  329,  337 

Petalomania,  337 

Petersen,  Henning  E.,  work  of,  in 

Petri  dish,  figure  of,  622 

Peyritsch,  J.,  mentioned,  171 

Peziza  aeruginosa,  uses,  168;  aurantiaca, 
color  of,  53;  described,  167;  badia, 
occurrence  of,  167;  coccinea,  color  of, 
S3,  on  dead  twigs,  83 ;  described,  67; 
Fuckeliana,  61;  repanda,  figure  *of, 
167;  Willkommii  or  larch  canker,"i68 


Phacidiaceae,  characters  of,  165 
Pholiota  adiposa,  figure  of,  76;*on  living 

trees,  74 
Phallaceae,  character  of  family,  252 
Phallin,  56,  238,  239 
Phallomycetes,  246-252 
Phanerogamic  parasites,  298 
Phoma,  species  of,  262 
Phoradendron  flavescens,  as  a  parasite, 

303;  figure  of,  302 
Phosphorescent  fungi,  62 
Phosphorus,  influence  of,  278 
Photogens,  25 

Photographic  prints,  drawings  of,  666 
Photomicrographic  attachment  to  Edin- 

ger's  apparatus,  figure  of,  662 
Photomicrography,  method  of,  666 
Phototropism,  61 

Phragmidiothrix,  38;  multisepta,  38 
Phragmidium   violaceum,  fusion  of  ad- 
joining cell  nuclei,  191,  192 
Phycobacteriaceae,  37 
Phycomyces  nitens,  61;  structure  of,  100 
Phycomycetes,  45,  46,  50,  92 
Phyllactinia  corylei,  figure  of,  53 
Phylloclady,  337 
Phyllody,  337 
Phyllomania,  338 
Phyllosticta  paviae,  figure  of,  259;  soli- 

taria,  figure  of  section,  262;  on  apples, 

figure  of,  261;  species  of,  261  et  seq. 
Phylloxera    mentioned,    295;   vastatrix, 

391 
Phylogeny  of  Ascomycetales,  173,  174; 

of  fungi,  89,  90,  01;  of  Uredinales,  197 
Physarum     sinuosum,     figure    of,     17; 

ellipsoideum,     plasmodium     of,     12; 

psittacinum,  13 
Physcia  parietina  on  rocks,  53 
Physical  character  of  soil  as  determining 

cause  of  disease,  279 
Physical  features  of  bacteria,  636 
Physics  emphasized,  271 
Physiologic  diseases,  564 
Physiology  emphasized,  271 
Physiology  of  fungi,  54,  61 


771 


Phytase,  58 

Phytocecidia,  385 

Phytomyxa,  9;  leguminosarum,  11 

Phytomyxales,  8 

Phytopathological    Society,    American, 

411 
Phytopathology,     411;     definition     of, 

272 
Phytophthora  infestans,   315,   542;   es 

cape  of  zoospores,  67;  infection  by,  273 
Pichia,  141 

Pilacraceae,  characters  of  family,  217 
Pilobolus,  figures  of  species,  102;  crys- 

tallinus    and  horses,   68;   occurrence 

of,  83 
Pineapple  chlorosis,  650 
Pink  disease  of  cacao,  490 
Piptocephalidacea;,  characters  of,  103 
Piptocephalis  parasitic  on  Mucor,  83 
Pistillody,  338 
Pith  flecks,  294 
Placing  of  cement,  321 
Plague,  35 

Planococcus,  35;  citreus,  35 
Planosarcina,  35 
Plant  juices,  598 
Plant      pathology,      growth     of,     410; 

special,  411  et  seq. 
Plants  as  disease  producers,  298 
Plasmodiocarps,  13 
Plasmodiophora,    9;    alni,    9;    brassicas, 

9,  387,  487,  488;  on  cabbage  roots, 

figure  of,  488;  figure  of,  10;  eleagni,  9 
Plasmodium,  aggregate,  8;  colors  of,  12; 

malarias,  18;  movement  of,  12 
Plasmopara   viticola,    513;    distribution 

of,  84;  figure  of,  113 
Plasmolysis,  experiments  with,  653 
Plate  counter,  628 
Plectenchymatous,  258 
Plectasciinea?,  characters  of,  143 
Plectridium,  25 
Pleiomorphy,  338 
Pleiophylly,  329,  338 
Pleiotaxy,  338 
Plesiasmy,  338 
48 


Pleurotus,  'description  of  genus,  737; 
olearius,  62;  ostreatus,  description  of, 
738;  figure  of,  738;  serotinus,  de- 
scription of,  738,  739;  sapidus,  de- 
scription of,  738;  ulmarius,  descrip- 
tion of,  739 

Plowrightia,  description  of  several  spe- 
cies, 162;  raorbosa,  74,  540;  distribu- 
tion of,  84;  figure  of,  73 

Plugging  test-tubes,  586 

Plum,  black-knot  of,  540;  pockets,  74,541 

Pod-spot  of  pea,  534 

Podospheera,  key  to  species,  722 

Poisoning  by  fungi,  symptoms,  238,  239 

Poisonous  substances  in  fungi,  238 

Pollaplasy,  338 

Polyangium,  40 

Polychrome  methylene  blue,  591 

Polyclady,  338 

Polyphagus  euglenae,  occurrence  of,  117 

Polyphylly,  338 

Polyporaceae,  characters  of  family,  224 

Polypores,  manual  of,  227 

Polyporoideas,  characters  of,  226 

Polyporus  borealis,  517;  mylittae,  sclero- 
tium  of,  71;  ofiicinalis,  analysis  of, 
55 ;  ponderosus,  539;  sapurema,  sclero- 
tium  of,  71;  sulphureus,  526;  figure 
of  fruit,  527;  figure  of  decaying  oak, 
528;  on  trees,  83;  with  trehalase,  58; 
tuberaster,  sclerotium  of,  71 

Polysphondylium  violaceum,  8 

Polystictus  abietinus  and  rotting  of 
slash,  75;  socer,  sclerotium  of,  72; 
versicolor,  64,  545 

Poppy,  fasciated,  figure  of,  336 

Poplar  cutting,  figure  of,  378 

Populin,  59 

Populus  pyramidalis,  cuttings  of,  379 

Potassium  hunger,  277 

Potato,  542;  as  medium,  596;  broth,  597; 
curly-dwarf  of,  576;  glycerinated,  596; 
juice,  596;  late-blight,  542;  rot, 
experiments  with,  643;  scab,  544 

Pouring  plates,  figure  of,  622;  method 
of,  622,  623 


772 


Powdery  dry-rot  of  potato,  543 
Powdery    mildew    of    cherry,    491;    of 

lilac,  522 
Predisposing  causes  of  disease,  272 
Preservation  of  wood,  692;  of  fungi,  726, 

727 
Prevention  of  disease,  bibliography  of, 

318 
Preventive  measures,  319 
Prints  of  spores,  728 
Prod'uction  of  spores,  63 
Prolification,  338 
Projection  apparatus,  657 
Prophylaxis,  298,  317 
Prosoplasms,  376,  395 
Prosoplastic  hypertrophy,  364 
Protease,  58,  59 
Protective  tissues  in  galls,  398 
Proteins,  splitting  of,  ^$,  59 
Protista,  7 
Protoasciineae,  131 

Protomyces,  occurrence  of  species,  121 
Protomycetacese,  121 
Protophyta,  7 
Protoplasm  of  fungi,  53' 
Prototrophic  organisms,  28 
Protozoa,  7 
Pruning  careless,  310;  unskillful,  figure 

of,  310 
Pseudomonas,    31?,    36;    brassicse,    485, 

486,  487;  campestris,  36,  645;  europaeus 

37;  hyacinthi,  36;  indigofera,   length 

and    breadth    of,     22;    putida,    37; 

pyocyanea,   37;    Stewarti,   644;   syn- 

cyanea,  37;  tumefaciens,  34,  388,  643; 

involution  forms  of,  365;  vascularum, 

.36 
Pseudopeziza      medicaginis,      169;      on 

alfalfa,  476,  477 
Ptomaines,  23 

Pucciniaceae,  characters  of  family,  201 
Puccinia  asparagi,   483,  484;  character 

of,    191;    coronifera,    531;    forms    of, 

202;    coronata,    forms   of,    202,    203; 

glumarum,  forms  of,   203;  graminis, 

560;    distribution   of,    84;    figure    of, 


188;  forms;  of,  191,  201,  202;  malva- 
cearum,  206,  517;  figure  of,  518; 
species  of,  203,  204,  205,  206 

PufT-balls,  239,  240 

Puffing  of  spores,  66 

Pumps  for  spraying,  figures  of,  691 

Punks,  342 

Pustules,  342 

Putrefaction,  ^3 

Pycnidial  pustules  of  chestnut  blight, 
499 

Pycnidiospores,  50 

Pycnidium,  50 

Pycnium,  188 

Pycnoconidia,  50 

Pycnospores,  50;  188;  germination  of 
chestnut  blight,  figures  of,  501 

Pyrenomycetiinese,  characters  of,  159, 
1 60 

Pyronemaceae,  characters  of,  165 

Pyronema,  life  cycle  contrasted  with 
fern,  126;  confluens  and  sexuality, 
165;  reinvestigation  of ,  by  P.  Claussen, 
123;   work   on  by  R.  A.  Harper,  122 

Pythiacystis  citriophora,  520;  on  lemon, 

85 
Pythium  de  Baryanum,  distribution  of, 
84 


Quarantine  to  prevent  disease,  317 
Quercus  reticulata  parasitized  by  Cono- 

pholia  mexicana,  299 
Quercus  Wislizeni,  figure  of  section  of 

gall,  399;  gall  on,  398 
Quick-drying  varieties  of  plants,  273 


Races  of  moulds,  95 

Rachitism,  338 

Raffinase,  58 

Ralfinose,  58 

Rafflesiaceae,  parasites  of,  301 

Raspberry  anthracnose,  544 

Rate  of  spore  fall,  64 


773 


Razoumofskya    Douglasii    laricis    as   a 

parasite,  304 
Recrudescence,  338 

Red  clover,  figure  of  tubercle  section,  389 
Red  gum,  545 
Red-rot  of  pine,  539 
Red  spider,  296 
Reduction  in  size,  342 
Regeneration,  355 
Reindeer  lichen  on  ground,  83 
Rennin,  59 

Replacement,  342,  347 
Reproduction  in  bacteria,  24 
Resin  in  fungi,  56 
Resinosis,  343,  350 
Resin  wash,  521 
Resistance  to  disease,  325 
Restitution,  355,  356,  357;  meaning  of 

word,  355;  process  of,  355 
Reticularia  lycoperdon  withajthalium,i7 
Reticularia,  spores  of,  16 
Retting  of  fibers,  li:^ 
Reynolds,  Ernest  Shaw,  mentioned,  271 
Rhabdochromatium,  39 
Rhizinaceae,  171 

Rhizobium  leguminosarum,  29,  36 
Rhizocallesy,  338 
Rhizoctonia  solani,  269 
Rhizomorph,  figure  of,  47 
Rhizomorpha  subterranea,  figure  of,  47 
Rhizopus     nigricans,      chitin     in,     52; 

conjugation   of,    94;    figure    of,    100; 

occurrence  of,  82;  structure  of,  99 
R.hodobacteriaceae,  38 
Rhodomyces  Kochii,  61 
Rhytisma  acerinum,  523;  on  maple,  165 
Ribes  aureum,  figure  of  hypertrophied 

bark,  367 
Ringing  of  trees,  295 
Roentgen  rays  and  fungi,  62 
Rcestelia,    188;    aurantiaca,    figure   of, 

204;    on    apple,   diagram  of,  212;  on 

apple  leaf,  figure  of,   210;  on  apple, 

magnified  view,  211 
Rodents  and  truffles,  68;  injury  by,  294 
Root  asphyxiation,  565;  parasites,  299 


Root-rot  of  oak,  530;  of  tobacco,  550; 
figure  of,  551 

Roquefort  cheese,  704,  705 

Rose  chafer,  figure  of,  275 

Rosellinia  quercina  on  oak  seedlings,  163 

Rosettes,  342 

Rostafinski  mentioned,  7 

Rotation  of  crops  to  prevent  disease,  317 

Rottenness,  352 

Rotten  wood,  307 

Rotting,  343,  352;  of  brush,  75 

Rozites  gongylophora  and  the  tugging- 
ant,  365;  as  food  for  tropic  ants,  71 

Ruppia  rostellata,  11 

Russula,  48;  description  of  genus,  742; 
emetica,  742;  in  forest  litter,  83; 
nigricans  parasitized  by  Nyctalis 
asterophora,  figure  of,  43,  with  tyro- 
sinase; ochrophylla,  description  of, 
743;  roseipes,  description  of,  743; 
rubra,  description  of,  743;  virescens, 
color  of,  53;  description  of,  743;  in 
forest  litter,  83 

Rust  fungi,  187;  occurrence  of,  86; 
lesion  on  apple  leaf,  section  of,  213; 
life  cycles,  forms  of,  189;  of  alfalfa, 
477;  of  asparagus,  191,  483,  484; 
of  beet,  485;  of  clover,  502;  of  coffee, 
503;  of  cotton,  508;  of  hollyhocks, 
203,  517;  of  oat,  531 

Rust,  spore  relations,  diagram  of,  190 

Rusts,  bibliography  of,  214,  215,  216; 
cytology  of,  191;  life  cycle,  195 

Rye,  546 


Saccharomyces  anomalus,  40;  aquifolii, 
140;  cartilaginosus  in  Kefir,  104; 
cerevisise,  52;  description  of,  138; 
figure  of,  135;  ellipsoideus,  descrip- 
tion of,  139,  140;  figure  of,  139;  of 
nuclei  and  division,  136;  exiguus, 
140;  fragilis  in  Kefir,  140;  ilicis,  140; 
Ludwigii,  141;  octosporus  with  mal- 
tase,  58;  Pastorianus  I,  140;  pyri- 
formis,  150;  Vordemanni,  140 


774 


INDEX 


Saccharomycetaceae,  characters  of,   134 

Saccharomycetiinese,  134 

Saccharomycodes,  141 

Saccharomycopsis,  141 

Sake,  146 

Salicin,  59 

Salmon,  Ernest  S.,  monograph  of,  157 

Salpinganthy,  338 

Sandalwood,  parasitism  of,  298 

Santalum    album,    parasitic   on    Acacia 

leucophsa,    298;    on    roots  of  Melia 

azidarachta,  298 
Saponaria  officinalis,  anther  smut  of,  72 
Saprogenic  organism,  33 
Saprogens,  25 
Saprolegnia,  44;  ferax  on  fishes  no,  in; 

structure    of    various    species,     no; 

escape  of  zoospores,  67 
Saprolegniacec-e,  cellulose  inj  52;  charac- 
ter of  family,  no 
Saprophyte,  42 

Sap-rot  of  red  gum,  545;  of  timber,   558 
Sarcina,   35;   aurantiaca,   35;  fiava,  35; 

lutea,   35;   maxima,  diameter  of,  22; 

rosea,  35;  ventriculi,  35 
Sarcosphaera,   figures  of  several  species, 

166 
Scab  of  apple,  479,  480,  481;  figures  of, 

480;  of  potatoes,  544 
Scald  of  cranberry,  509 
Scarification  of  trees,  295 
Schizomycetes,  i;  origin  of  name,  21 
Schizonema    imbricator,    a  scale  insect 

and  Scorias  spongiosa,  72 
Schizophyllum  commune,  64;  figure  of, 

77;  xerophytic  habits  of,  78 
Schizosaccharomyces,  141 
Schmitz,  J.,  mentioned,  61 
Sclerodermaceae,    characters   of   family, 

246 
Scleroderma  vulgare  on  old  stumps,  83 
Sclerotia,  69;  fungi  bearing,  71 
Sclerotinia  libertiana,  522,  644;  descrip- 
tion of  several  species,  168;  sclerotia 

of,  69;  figure  of,  168 
Sclerotium,  48 


Scorias  spongiosa,  158;  life  history  of,  72 

Scrophulariacese,  parasites  of  family,  299 

Scyphogeny,  338 

Sectioning  methods,  633,  654 

Sectorial  chimseras,  330 

Sepalody,  338 

Septoria     leaf-spot,     figures     of,     263; 

species  of,  264 
Sequoia  gigantea,  annual  rings  of,  358 
Serum  of  blood,  604 
Sexual  act  in  slime  moulds,  16 
Sexual    reproduction    in    Oomycetales, 

107;  in  Sphserotheca  Castagnei,  155; 

in    moulds,    93;    in    Ascomycetales, 

bibliography    of,    129,    130;   of    As- 
comycetales, 122,  123 
Shaggymane,  figure  of,  749 
Shot-holes,    342,  345;    of   plum   leaves, 

figure  of,  345 
Silene  inflata,  anther  smut  of,  72 
Silverberry,  9 

Size  of  bacterial  cells,  21,  22 
Skatol,  ^i 

Skeleton  leaves,  294 
Slant  of  vegetables,  figure  of,  597 
Sleeping  disease  of  tomatoes,  646 
Sliding  microtome,  figure  of,  654 
Slime  flux,  343 
Slime  moulds,  bibliography  of,   18,   19, 

20;    distribution    of,    18;    laboratory 

exercises  with;  in  general,  7 
Smelter  fumes,  effect  of,  289,  290,  291 
Smith,    Erwin    F.,    quoted    on    peach 

yellows,  315;  work  of,  34,  387 
Smoke,  effect  of,  289,  649 
Smut  boil  of  corn,  figure  of,  504,  505,  506 
Smut  explosions,  182 
Smut  of  oats,  figures  of,  532;  of  onion, 

S31;  spores,  germination  of,  181 
Smuts,   178-186;  bibliography  of,   185, 

186;  genera  of,   182;  of  anthers,   72; 

modes  of  infection,  181 
Snow  action,  295;  influence  of,  284 
Soft  rot,  343 
Soja  sauce,  146 
Solenoidy,  338 


INDEX 


775 


Solid  vegetable  substance,  598 

Solution  338;  normal,  613 

Soot,  effect  of,  289 

Sooty  mould  of  orange,  521 

Sorauer,  P.,  book  of,  564 

Sordariaceae,  characters  of,  162,  163 

Sorosphaera,  9;  veronicae,  ii 

Soy  bean,  figure  of  nodules  on  roots,  29 

Sparassis  crispa,  223 

Special  plant  pathology,  411  et  seq. 

Speiranthy,  339 

Spermogonium,  187 

Sphaeria  carpophila,  61 

Sphaeriaceae,  characters  of,  163 

Sphasrobolaceae,  characters  of  family,  246 

Sphasrochorisis,  339 

Sphajronema  fimbriata,  548 

Sphaeropsidales,  260 

Sphaeropsis  malorum,  262;  figures  of 
spots  due  to,  344;  on  apple,  478,  479; 
tumefaciens,  647 

Sphaerotheca  Castagnei,  sexual  repro- 
duction in,  155;  key  to  species  of,  722 

Sphaerotilus,  38 

Spirillaceae,  37 

Spirillum,  37;  berolinense,  37;  comma, 
37;  danubicum,  37;  parvum,  thickness 
of,  21;  rufum,  37 

Spirochaeta,  37;  dentium,  37;  Ober- 
meieri,  37;  pallida,  37 

Spiroism,  339 

Spirosoma,  37 

Spontaneous  chimaeras,  330 

Sporabola,  234 

Sporangiospores,  50 

Spore  discharge  in  mushrooms,  233, 
234;  figure  of,  64 

Spore  fall  in  Amanitopsis  vaginata, 
figure  of,  65;  rate  of,  64 

Spore  formation  in  moulds,  96;  germina- 
tion, 61;  prints,  728;  production,  63 

Spores  of  yeasts,  622;  of  rusts,  nuclear 
phenomena  in,  192 

Sporodinia  grandis,  conjugation  of,  94; 
occurrence  of,  loi 

Sporulation  in  yeasts,  137 


Spot  disease  of  violet,  558 

Spots,  colored,  342 

Spray  calendar,  680-690 

Spray  pumps,  figures  of,  691 

Spraying  for  plant  protection,  318 

Sprays,  669  et  seq. 

Spruce  gum,  collection  of,  352 

Squared  cover-glasses,   616;  figures  of, 

617 
Squashes,  525 
Stab  cultures,  types  of,  627;  in  figure> 

627 
Stage  micrometer,  582 
Stag-head,  395,  565 
Staining  bacteria,  588 
Stains,  589-592 
Staminody,  339 

Standardization  of  culture  media,  613 
Stasimorphy,  339 
Statement,  general,  i 
Steeps,  677-678 

Stemonitis    ferruginea,   spores    of,    16; 
flaccida,  spores  of,  16;  fusca,  figure  of, 
14 
Step  micrometer,  585;  figure  of,  586 
Stereonemata,  15 

Stereum,  221,  222;  fasciatum,  and 
rotting  of  slash,  75;  frustulosum,  553; 
rameale  and  rotting  of  slash,  75;  ura- 
brinum  and  rotting  of  slash,  75; 
versiforme  and  rotting  of  slash,  75 
Sterigmatocystisniger,  character  of,  147; 

figure  of,  149 
Sterilization,  625 
Stesomy,  339 

Stevens,  Neil  E.,  mentioned,  84 
Stigmatomyces  Baeri,  structure  of,   172 
Stippen,  570 
Strains  of  moulds,  95 
Strangulation,  294 
Strasburger,  Ed.,  cited,  15 
Streak  cultures,  t3T)es  of  in  fungi,  634 
Streak  method  of  Bergey,  623 
Streak  of  sweet  pea,  547 
Streptococcus,     34;     erysipelatos,     34; 
mesenterioides,  34;  pyogenes,  34 


776 


Streptothrix,  37;  fluitans,  37 

Strobilomyces  strobilaceus,  230 

Strophomany,  339 

Structure  of  lichen  thallus,  81 

Stub,  figure  of,  311 

Students     of     nuclear    phenomena     in 

fleshy  fungi,  218,  219 
Students,  suggestions  to,  407 
Sturgis,    W.     C,    literature    of    plant 

diseases,  411 
Stylospores,  50 
Succulence,  abnormal,  368 
Sucrose,  58 
Sucking  insects,  565 
Suffocation,  565 
Suffulcra  of  Erysiphaceae,  155 
Sugar  beets,  curly-top  of,  573 
Suggestions   to   teachers   and  students, 

407-410 
Sulphur  bacteria,  28;  influence  of,  278 
Sunscald,  282 
Sunscorch,  282 
Suppression,  339 
Surgery  of  trees,  319  et  seq.;  figures  of, 

320 
Susceptibility  to  disease,  325;  to  infec- 
tion, 273 
Sweet  pea  diseases,   experiments   with, 

647;  streak,  547 
Sweet  potato  black-rot,  548 
Swingle,  Dean  B.,  studies  on  columella 

formation,  96 
Sycamore,  549;  blight,  549 
Symbiotic,  49 
Symptomatology,  341 
Symptoms,     description     of,     640;     of 

disease,  341;  of  poisoning,  238,  239 
Synandry,  339 
Synanthody,  339 
Synanthy,  339 
Syncarpy,  339 
Synchytrieae,  117 
Synchytrium,     parasitism     of     various 

species,  117;  vaccinii,  509 
Syncotylous  races,  329 
Synophthy,  339 


Synspermy,  339 

Syphilis,  37 

Systematic  account  of  bacteria,  34 

Systematic  ■  bacteriology,      630,      631; 

botany  emphasized,   271;  position  of 

fungi  imperfecti,  260 


Taka-diastase,  58,  146 
Tannin  as  a  protective  substance,  274 
Taphrina  cserulescens  on  oaks,  85 
Taphrina,  description  of  various  species, 

134;  of  figures  of,  132 
Tas  Gu  of  Java,  146 
Taubenhaus,  J.  J.,  work  of,  274 
Taxitery,  339 

Teachers,  suggestions  to,  407 
Teaching  methods,  407-410 
Telegraph  wires,  injury  by,  310 
Teliosorus    of    cedar    apple,   figures    of 

section,  193,  194,  207 
Teliospores,    187;  of  cedar  apple  rust, 

figures  of,  208 
Telium,  187 
Teleutospore,  187 
Teratology,  331;  book  on,  340 
Terfas  as  food  of  Arabs,  151 
Terfeziacese,  character  of,  151 
Terfezia,   character   and   occurrence   of 

various  species,  151 
Test-tube  plugging,  586 
Tetramyxa,  9;  parasitica,  11 
Tetranychus  mytilaspidis,  296 
Thalloid  shoot  of  Lunularia,  figures  of, 

361 
Thallophytes,  i 

Thamnidium  chffitocladioides,  loi,  char- 
acter   of    species    of,    102;    elegans, 

figure  of,  loi 
Thaxter,  Roland,  work  of,  172 
Thelephoraceae,    characters    of    family, 

221 
Thermogens,  25 
Thesium  alpinum,  298 
Thielavia  basicola,  550;  figures  of,  551, 

552;  pathogenicity,  149,  150 


777 


Thiobacteriaceae,  38 

Thiocapsa,  39 

Thiocystis,  39 

Thiodictyoiij  39 

Thiogens,  25 

Thiopedia,  39 

Thiophysa  volutans,  diameter  of,  22 

Thiopolycoccus,  39 

Thiosarcina,  39 

Thiospirillum,  39 

Thiothece,  39 

Thiothrix,  38;  nivea,  38 

Thoma's  haematimeter,  617;  details  of, 

618,  620 
Threshing  machine  active  in  spread  of 

smuts,  179 
Thyridaria  tarda,  490 
Tillet,  Matthieu,  mentioned,  182 
Tilletiaceae,  characters  of,  182 
Tilletia,  descriptions  of  various  species, 

184,  185 
Tilletia  foetans,  chlamydospores  of,  561; 
tritici,  description  of,  184;  figure   of, 
183 
Tilmadoche  mutabilis,  figure  of,  17 
Timber  decay,  553 
Timber  sap-rot,  558 
Tip-burn  of  potato,  575 
Tissue  forms  of  cecidia,  397 
Toodstools,    231    et   seq.;   guide  to  de- 
scription of,  728,  729 
Tobacco,   550;  mosaic  disease  of,    578; 

root-rot,  550;  section  of  tumor,  392 
Toothwort  as  a  root  parasite,  299 
Top-dry,  565 
Tornadoes,  injury  by,  311 
Torsion,  339 

Toxicology  of  mushrooms,  237,  238,  239 
Trama,  232 

Trametes  pini,  519;  radiciperda,  injury 
by,  311;  robiniophila,  occurrence  of, 
228;  species  of,  229;  suaveolens, 
occurrence  of,  228 
Transfer  of  fungi,  624 
Tranzschelia  punctata  attack  on  Hepat- 
ica  triloba,  348 


Traumatism,  294 

Treatment  of  cavities,  321 

Tree  surgery,  figures  of,  320;  literature 

on,  324;  in  general,  319 
Trehalase,  58 
Trehalose,  53,  58 
Trembling  fungi,  217 
TremellacesB,  characters  of  family,  217; 

mucilage  in,  52 
Trichia,   15;  chrysosperma  with  yellow 
elaters,    17;   fallax,   15;  scabra,  Plas- 
modium   of,    12;    varia    with    yellow 
sporangia,  17 
Trichothecium  roseum,  61;  chitin  in,  52 
Tricotylous  races,  329 
Trimethylamin    in    spores    of    Tilletia 

caries,  56 
Tripe  de  roche,  83 
Triplasy,  339 
Trophic  correlation,  404 
Trophomorphosis,  404 
Tropisms  of  plasmodia,  12 
Trommelschlagel,  25 
Truflles  and  rodents,  68 
Truffles,  occurrence,  151,  153 
Trypsin,  58,  59 
Tuberaceae,  characters  of,  151 
Tubercles  of  velvet  bean,  figure  of,  386 
Tuber,    characters    of    various    species, 
153;    figures   of,    152;    Requenii   and 
black  beetles,  71 
Tubeuf,  Carl  von,  quoted,  553 
Tubifera  Casparyi,  plasmodium  of,  12; 

ferruginea  red  plasmodium  of,  12 
Tuckahoe,  72 
Tugging-ant  and  Rozites  gongylophora, 

365 
Tumescence,  352 

Tumor  on  apple  stem,  figure  of,  390 
Tumor,  figure  of  section  of  tobacco,  392 
Tumors  in  plants,  34,  342 
Turnips,  brown- rot,  figure  of,  486 
Tyloses,  370;  figure  of,  369 
Tylostomacese,  241 

Types   of   colonies,    626,   627;   of   stab 
cultures,  627 


778 


INDEX 


Tyrosin,  33 

Tyrosinase,  58,  59 

Twin  cherries,  figures  of,  334 

U 

Ultramicroscopic  organisms,  21 

Umbilicaria  on  Octorara  schist,  83 

Uncinula,  key  to  species  of,  725,  726 

Unhappy  white  elm,  figure  of,  287 

Unorganized  ferments,  56 

Urease,  59 

Urea-splitting  enzymes,  59 

Uredinales,  187;  phylogeny  of,  197 

Uredineae,  187;  characters  of,  187 

Urediniospores,  188 

Uredinium,  188 

Uredo  gossypii,  508 

Uredospores,  49,  188 

Urobacillus      Duclauxii,      length     and 

breadth  of,  22 
Urocystis  cepulas,  531;  several  species, 

185 
Uromyces  betae  on  beets,  485;  figure  cf 

species,  200;  species  of,  201;  striatus 

on  alfalfa,  477;  trifolii,  502 
Usnea  barbata,  mechanic  tissues  of,  81; 

the  beard  lichen,  83 
Ustilaginaceas,  characters  of  family,  178 
Ustilago    avenae,    figures    of,    532;    of 

several  species,  180;  levis,  figures  of,- 

532;   maydis  on  maize  and  teosinte, 

86;  origin  of  name,  178;  zeae,  504,  505, 

5c6;  figure  of,  505;  tritici,  figures  of, 

562 


Vaccination,  314 

Vaccinium  vitis-idasa,  gall  on,  389 

Valsaceae,  characters  of,  163 

Van  Wisselingh,  C,  work  of,  52 

Variegation,  343 

Vaucheria,  44 

Vegetable  slant,  "figure  of,  597 

Velum  partiale,  232 

Velum  universale,  232 


Velvet  bean  tubercles,  figure  of,  386 
Venturia     inequalis,     479,     480,     481; 

figures  of,  480;  pomi,  163 
Verpa  digitaliformis,  171 
Verticillium  albo-atrum,  646 
Vibio  cholera,  rapidity  of  cell  division,  24 
Villia,  141 

Violet  leaf-spot,  figure  of,  559 
Violet  spot  diseases,  558 
Virescence,  339 
Volutin  in  fungi,  53 
Volva,  232 

Von  Tavel,  Dr.  F.,  cited,  89 
Von  Wettstein,  R.,  mentioned,  61 


W 


Wager,  Harold,  work  of,  135 

Wallroth  mentioned,  7 

Walter,  H.,  work  of,  271 

Ward,  H.  M.,  and  ginger  beer  organisms, 
140 

Water  analysis,  626 

Water  content  of  tissues  and  disease,  280 

Water-core  of  apple,  571 

Water,  influence  of,  279 

Water-logging,  567 

Watermelons,  525;  wilt  of,  646 

Water  requirements  of  plants,  279,  280 

Wettstein,  R.  von,  2 

Wheat,    560;    broth,    599;    rust,     188; 
forms  of,  201,  202;  smut,  figures  of,  562 

White  pine  blister-rust,  537 

White  rust  of  cruciferous  plants,  74 

Whey,  litmus,  600 

Will,  Dr.  H.,  142 

Wilt,  342 

Wilting,    342,    345,    346;    experiments 

with,  652,  653 
Wilt  of  corn,  507;  figure  of  experiment 
with,  646;  of  cotton,  experiments 
with,  646;  of  cowpeas,  646;  of  egg 
plant,  646;  of  melons,  525;  of  sweet 
corn,  644;  of  watermelon,  646 
Wilson,  Lucy  L.  W.  on  Conopholis 
americana,  301 


INDEX 


779 


Wind  action,  295;  dissemination  of  smut 
spores,  179;  distribution  of  spores, 
66;  its  influence  on  plants,  286 

Wind-swept  white  poplar,  figure  of,  287 

Winkler,  H.,  work  of  on  graft  hybrids, 
330 

Winogradsky,  mentioned,  54 

Winter,  G.,  mentioned,  61 

Winterstein,  research  of,  52 

Wire  basket,  figure  of,  624 

Wire  worms,  651 

Witches'  brooms,  72,  342,  348,  395; 
on  hackberry,  figure  of,  351 

Withering,  652 

Wood-boring  insects,  310 

Woody  fungi,  218  et  seq. 

Worsdell,  W.  C,  book  of,  340 

Wound-cork,  376;  description  of,  383 

Wounding  of  plants,  artificial,  648 

Wound- wood,  376,  381,  382 


Xylaria  Cookei,  62;  digitata  on  old  wood, 
164;  hypoxylon,  62;  polymorpha  on 
old  tree  stumps,  164 

Xylariaccae,  characters  of  family,  164 


Yeasts,  52;  134  et  seq.;  counting  cells 
of,  617;  character  of  fermentation, 
i37i  595!  filrn  formation,  137;  on 
gypsum  blocks,  622;  spores,  622; 
sporulation,  137,  with  zymase,  59 

Yellow  rust  of  wheat,  203 

Yellows  of  peach,  573 

Yolk  of  eggs,  603 

Youngken,  H.  \V.,  39 


Zeiller,  work  on  fossil  fungi,  82 

Zdocecidia,  385 

Zoogloea,  23 

Zoology  emphasized,  271 

Zopf,  W.,  cited,  7,  53,  56;  handbook  of, 

55 

Zygo my ce tales,  5c;  absence  of  cellulose, 
52;  bibliography  of,  105;  character 
of  order,  92,  93;  key  to  families,  97 

Zygosaccharomyces,  141 

Zygospores,  50 

Zymase,  56,  59 

Zymogen,  57 

Zj^mogens.  25 


^BOPtRfY  UBRARY 

W.  C.  State  CMtge 


( 


'^ 


